Free runtime calculator· UK units

Power Station Runtime & Sizing

Add the fridge, the CPAP and the kettle. See hours of runtime for each of our picks, the watt-hours you need, and solar recharge time for your region.

Data checked 19 September 2026 · No sign-up · Feeds power-stations, tyre-inflators

Step 1

What do you want to run?

  • 12 V compressor fridge, 35 to 45 L

    about 14 W average, 98 W peak · Dometic CFX3 45: 12.4 W average at 32 °C ambient (about 300 Wh a day). A 12 V compressor fridge duty-cycles, so it draws 2 to 4 A only while the compressor is running.

    Per day336 Wh

  • Kettle, 3,000 W (the standard UK kettle)

    180 Wh per boil · The classic British load, and the one that decides which power station you need. CSE rates a kettle at 3,000 W and Electrical Safety First at 2,200 to 3,000 W, up to 13 A, which is the full rating of a UK socket. Energy per boil is 150 to 180 Wh for a full 1.7 L, about half that for a mug or two; the sources for that are secondary, so we publish the top of the band. The problem is never the watt-hours, it is finding 3,000 W of inverter.

    Per day720 Wh

  • Phone, full charge

    18 Wh per charge · A 14 Wh phone battery plus charging losses.

    Per day36 Wh

Step 2

For how long, and how hot?

days

A compressor fridge cycles far harder in a heatwave, so we add a third to fridge and freezer draw. Nothing else on the list changes.

Your numbers

What you need

Per day

1,239Wh

1,092 Wh at the appliances

2-day trip

2,477Wh

out of the battery

Buy at least

2,973Wh

with a 20% margin

Inverter needs

3,000W

peak; 3,000 W running

Something on your list wants more than 1,800 W. That is the number to check on the specification, not the watt-hours: most portable stations stop at 1,800 to 2,400 W continuous and only flagship units reach 3,000 W, so a standard 3 kW British kettle is out of reach for nearly all of them. A 2.2 kW kettle uses the same energy per boil and asks 800 W less of the inverter.

Our picks

Which power station fits?

    Picks from our portable power station ranking, in order of fit. As an Amazon Associate we earn from qualifying purchases.

    Step 3

    Recharging from solar

    Peak sun

    2.9h/day

    London, year average

    Real panel output

    150W

    75% of the sticker rating

    To replace a day's use

    8.3 h

    about 2.8 sunny days

    Peak sun hours are NASA POWER 20-year monthly means. Be honest about the winter column before you plan around solar: London averages 0.66 peak sun hours in December and Glasgow 0.37, against 2.94 and 2.55 across the year, so a midwinter recharge that takes a morning in June takes the best part of a week. Cloud and a flat panel cut it further; a panel tilted at the sun and moved twice a day gets closer to its rating.

    Off the grid

    Campsite hook-up and 110 V site power

    A hook-up bollard is not a house socket. Each pitch has its own MCB and RCD, and the rating is the whole pitch: everything you plug in shares it. Club sites are usually 10 A or 16 A, but smaller and rural sites are often 6 A only, which is why both clubs warn against bringing an ordinary domestic kettle.

    Hook-upWatts at 230 VWhat that means
    6 A1,380 WCommon on smaller and rural sites, and the one that catches people out. A fridge, a charger, a TV and a low-wattage kettle is about the limit; add an electric heater and the bollard trips.
    10 A2,300 WThe usual rating on Camping and Caravanning Club sites. Still below a 3 kW domestic kettle, which draws 13 A on its own.
    16 A3,680 WThe top standard hook-up rating, on the better-equipped pitches. Enough for a 3 kW kettle on its own, and nothing else at the same time.

    On site the tools are 110 V centre-tapped-earth, 55 V each leg to earth, which halves the shock voltage. The transformer takes 220 to 240 V in on a 13 A BS 1363 plug, so whatever the kVA badge says the input can never exceed about 3 kW. Size a power station against the continuous column, not the intermittent one.

    TransformerIntermittentContinuousOutletsWeight
    1000/2/BOne small tool at a time.1 kVA0.6 kVA2 x 16 A12.5 kg
    1500/2/BLights and a drill, or one grinder intermittently.1.5 kVA0.9 kVA2 x 16 A13 kg
    3000/2/BThe usual choice: enough for most single-tool work or one submersible pump.3 kVA2.2 kVA2 x 16 A18 kg
    5000/3/BTwo 16 A tools plus a 32 A outlet. Note the badge is 5 kVA and the continuous rating is 2.8 kVA, and it still arrives on a 13 A plug.5 kVA2.8 kVA2 x 16 A + 1 x 32 A29 kg

    Corded tools

    Will a 13 A socket and this lead cope?

    W
    m

    Current

    8.7A

    at 230 V

    Socket

    13 A

    a standard 13 A socket is fine

    Volt drop

    1.8%

    lead is fine

    A BS 1363 socket is rated 13 A, which is about 2,990 W at 230 V, and every UK plug carries its own fuse, sized for the appliance rather than the socket. Past 13 A you are into a 16 A blue commando outlet or a campsite hook-up. Keep volt drop under 5% on motor tools, and unwind the reel fully. Physics only; the wiring rules are BS 7671 and an electrician's call.

    Library

    Appliance figures used above

    ApplianceAveragePeak12 V?Typical day
    12 V compressor fridge, 35 to 45 LDometic CFX3 45: 12.4 W average at 32 °C ambient (about 300 Wh a day). A 12 V compressor fridge duty-cycles, so it draws 2 to 4 A only while the compressor is running.14 W98 WYes24 h
    12 V compressor fridge, 50 to 65 LDometic CFX3 55: 13.3 W at 32 °C. A British summer is kinder than the test condition, so treat this as the top end.15 W107 WYes24 h
    12 V dual-zone fridge/freezer, 75 to 95 L, freezer runningDometic CFX3 75DZ: 36.5 W and 95DZ: 43 W at 32 °C with the freezer at −15 °C; fridge-only mode roughly halves it.40 W125 WYes24 h
    3-way absorption caravan fridge on 12 VAbout 170 W continuously: there is no thermostat on the 12 V element, so it draws the lot the whole time it is switched on and will flatten a power station in hours. The mains element is 250 W and on gas it draws almost nothing. Run it on gas when you are parked. The 170 W comes from a Dometic RMF8505 rating plate quoted on an owners' forum rather than from a Dometic datasheet, so treat it as indicative.170 W170 WYes24 h
    Fridge (230 V)The Centre for Sustainable Energy gives 150 W and Electrical Safety First 120 W (0.5 A) while running; the compressor cycles, so the daily total is far below 150 W × 24 h. No UK source publishes a start-up surge, so the peak here is five times the running figure, which is the usual rule of thumb for a compressor.150 W750 WNo24 h
    Fridge-freezer (230 V)CSE's figure for a combined fridge-freezer while running. Peak is five times running for the compressor start, which is a rule of thumb rather than a published figure.300 W1500 WNo24 h
    Freezer or chest freezer (230 V)CSE gives 150 W and Electrical Safety First 200 W (0.86 A); we use the higher. A freezer in an unheated garage cycles less in a British winter than it does in July.200 W1000 WNo24 h
    Kettle, 3,000 W (the standard UK kettle)The classic British load, and the one that decides which power station you need. CSE rates a kettle at 3,000 W and Electrical Safety First at 2,200 to 3,000 W, up to 13 A, which is the full rating of a UK socket. Energy per boil is 150 to 180 Wh for a full 1.7 L, about half that for a mug or two; the sources for that are secondary, so we publish the top of the band. The problem is never the watt-hours, it is finding 3,000 W of inverter.180 Wh/boil3000 WNo4 boils
    Kettle, 2,200 WThe bottom of Electrical Safety First's kettle range, and the practical workaround: the same water takes the same energy, it just takes longer, so the inverter only has to find 2,200 W instead of 3,000 W.180 Wh/boil2200 WNo4 boils
    Microwave (about 1,000 W input)The number on the front of a microwave is cooking output, not what it draws. The rating plate on the back is input, which is what the power station has to supply, and conversion efficiency is only about 50 to 64%: an 800 W microwave typically pulls 1,200 to 1,500 W from the socket. CSE and Electrical Safety First both put a UK microwave at 1,000 W (6.5 A). Watt-hours here are five minutes at that draw.83 Wh/5-minute run1500 WNo2 5-minute runs
    Toaster, 2-sliceElectrical Safety First's figure. Watt-hours are three minutes at 900 W.45 Wh/round900 WNo2 rounds
    Toaster, 4-sliceElectrical Safety First's figure. Twice the slices for twice the watts, so about the same energy per slice. Watt-hours are three minutes at 2,000 W.100 Wh/round2000 WNo1 rounds
    Electric ovenCSE's figure. The element cycles once the oven is up to temperature, so the average over an hour is lower than the rating, but the inverter still has to start it.2100 W2100 WNo1 h
    Electric hob, one ringCSE's figure for a single ring, which is also the right order for a portable induction hob on a high setting. Two rings at once is beyond every portable station.2000 W2000 WNo0.5 h
    Slow cooker250 W on low up to 650 W on high, from a UK appliance wattage chart rather than a manufacturer, so treat it as indicative. The best value on this list: a whole meal for well under 2 kWh.250 W650 WNo6 h
    Coffee machine600 to 1,200 W from a UK appliance wattage chart rather than a manufacturer. It only draws that while the boiler is heating, which is most of a pod machine's cycle and very little of a filter machine's.1200 W1200 WNo0.25 h
    Washing machineCSE gives 2,100 W and Electrical Safety First 2,200 W (10 A). That is the heating stage; the drum motor alone is a fraction of it, so a cold wash is a completely different load from a 60 °C one.2100 W2200 WNo1 h
    Tumble dryer, heat pumpElectrical Safety First rates a heat pump dryer at 800 W and 3.5 A, and measurement logs put it at 400 to 500 W once it is up to speed, for 0.8 to 1.2 kWh a cycle. That is the one tumble dryer a large power station can genuinely run. We use the top of the measured band.1200 Wh/cycle1000 WNo1 cycles
    Tumble dryer, condenser2,500 W and 11 A, and 3.5 to 4 kWh a cycle, with one measured 9 kg machine reaching 5.2 kWh. Beyond most inverters on output and beyond every portable station on capacity.4000 Wh/cycle2500 WNo1 cycles
    Tumble dryer, ventedElectrical Safety First's standard tumble dryer figure is 2,500 W and 11 A, and a 9 kg vented cycle is about 5.3 kWh. This is the single sharpest line in the UK appliance table: a heat pump dryer is runnable off a big power station and a vented one is not, and they look identical from the front.5300 Wh/cycle2500 WNo1 cycles
    IronCSE's figure. The thermostat cycles, so the average over half an hour is lower than the rating.1500 W1500 WNo0.5 h
    Vacuum cleanerCSE gives 900 W; Electrical Safety First gives a 900 to 2,000 W range, so older pre-ecodesign machines sit at the top of it.900 W2000 WNo0.25 h
    Hair dryerCSE gives 2,000 W and Electrical Safety First 2,200 W (10 A). Watt-hours are five minutes at 2,000 W. Like the kettle, it is an output problem, not a capacity one.167 Wh/5-minute use2200 WNo1 5-minute uses
    Electric fan heaterElectrical Safety First put a radiator or fan heater at 2,000 to 3,000 W, up to 13 A. Resistance heating is the worst possible use of a battery: an hour on full flattens most stations.2000 W3000 WNo2 h
    Oil-filled radiatorCSE's figure. The thermostat cycles once the room is warm, so the average is below the rating, but the first hour is not.2000 W2000 WNo4 h
    Halogen heater800 to 1,500 W from a UK appliance wattage chart rather than a manufacturer. One bar on a three-bar heater is the setting a power station can live with.800 W1500 WNo3 h
    Electric heater (generic)CSE's general figure for a plug-in electric heater.2500 W2500 WNo2 h
    Electric blanket200 to 400 W from a UK appliance wattage chart rather than a manufacturer, and the thermostat cycles, so a night is well under 1 kWh. Cheaper than heating the room by a wide margin.200 W400 WNo8 h
    Immersion heaterCSE's figure. Listed so you can see the scale: an hour of immersion heating is 3 kWh, which is more than most power stations hold.3000 W3000 WNo1 h
    Electric showerCSE's figure, included precisely to show that it is impossible. An electric shower is on its own 40 A or 45 A circuit, it is three times what a 13 A socket can deliver, and no portable power station comes close.9000 W9000 WNo0.15 h
    12 V diesel heater, 2 kW classWebasto Air Top 2000: 14 to 29 W running; the glow plug pulls about 100 to 130 W for a few minutes at start-up (estimate). The reason van conversions use diesel rather than an electric heater.25 W120 WYes8 h
    CPAP without humidifier (ResMed AirSense 10, DC converter)ResMed's battery guide: 0.7 to 1.7 A at 12 V depending on pressure. Use the maker's DC converter, not the inverter.11 W25 WYes8 h
    CPAP with humidifier (AirSense 10, HumidAir setting 4)1.7 to 4.2 A at 12 V; the humidifier is most of the draw.28 W60 WYes8 h
    CPAP with humidifier on 8 and heated tube (AirSense 10)4.7 to 5.6 A at 12 V with ClimateLineAir at 30 °C. Turn the humidifier down to stretch a night.59 W104 WYes8 h
    CPAP, ResMed AirSense 11 with humidifier and heated tube40 to 55 W with HumidAir at level 2 or 3, and 5 to 35 W with the humidifier off. The peak is the power supply's own rating, 24 V at 2.71 A. These figures are third-party: ResMed's own power-consumption table could not be retrieved, so size from the documentation that came with your machine and keep a margin.55 W65 WYes8 h
    ResMed AirMini travel CPAP0.4 to 0.8 A at 12 V through the AirMini DC converter.6 W27 WYes8 h
    Oxygen concentrator, home 5 L (Philips EverFlo)Size from the manufacturer's figure for your flow setting and keep a margin.350 W400 WNo8 h
    Portable oxygen concentrator (Inogen One G5 class)120 W maximum DC input; draw depends on the flow setting (estimate).40 W120 WYes8 h
    Starlink MiniStarlink's own figure is 25 to 40 W average; owners log 16 to 20 W steady after the 2026 firmware. Runs from 12 V with a USB-C PD lead.30 W60 WYes8 h
    Starlink Standard (Gen 3)Starlink's figure is 75 to 100 W average; AC power supply only.85 W100 WNo8 h
    LaptopCSE's figure. The peak is the charger's rating rather than a measured draw: a 90 to 100 W USB-C brick only pulls that with the battery empty and the machine working.50 W100 WYes4 h
    Desktop PCCSE's figure. No UK source publishes a start-up or gaming peak, so the peak here is the same as the average; a gaming tower with a discrete card draws considerably more.140 W140 WNo4 h
    TV, 32 inch LEDSecondary source rather than a UK authority. Small LED sets are the cheapest mains load in a van by a long way.42 W42 WYes3 h
    TV, 43 inch LEDSecondary source rather than a UK authority.67 W67 WYes3 h
    TV, 55 inchElectrical Safety First put a 55 inch UHD set at 120 W. An efficient OLED is lower: LG's 55 inch G2 is rated 81 kWh per 1,000 hours of SDR viewing, which is 81 W.120 W120 WNo3 h
    Games consoleCSE's figure for a games console. A current console in a demanding game draws more than this, but no UK source publishes a peak, so plan with a margin.120 W120 WNo2 h
    USB or 12 V fanUSB fans draw 2 to 5 W; a 12 V oscillating fan 15 to 25 W (estimate).8 W25 WYes8 h
    Phone, full chargeA 14 Wh phone battery plus charging losses.18 Wh/charge25 WYes2 charges
    Tablet, full chargeiPad class, 28.6 Wh battery plus losses.34 Wh/charge30 WYes1 charges
    Drone battery, DJI Mini class (19 Wh)23 Wh/batterie40 WYes2 batteries
    Drone battery, DJI Air 3 class (63 Wh)75 Wh/batterie80 WYes2 batteries
    Camera battery (Sony NP-FZ100, Canon LP-E6NH)20 Wh/batterie20 WYes2 batteries
    18 V 5 Ah power tool battery90 Wh in the pack plus charger losses.108 Wh/charge180 WNo1 charges
    E-bike battery (500 Wh)Derived rather than published: a 500 Wh pack plus charger losses is about 550 to 600 Wh at the socket. A 36 V pack charges at 42 V and a 48 V pack at 54.6 V; standard chargers are 2 A or 3 A, so DC output is roughly 84 to 126 W and AC draw about 15 to 20% higher. A 48 V 15 Ah pack (720 Wh) takes 6 to 8 hours on a 2 A charger.580 Wh/charge180 WNo1 charges
    Put the station outside the tent where you can; if it has to be inside, keep it away from bedding and anything flammable and leave air around it. Every maker limits charging to 0 to 40 or 45 °C and running to about 45 °C, and a closed car in a heatwave passes both.Give a compressor fridge 50 mm of clearance on every side and 100 mm at the vents; a fridge that cannot breathe draws more, and the first 24 hours of pull-down cost the most.Run a CPAP from the maker's DC converter rather than the inverter, and never start a vehicle while the machine is powered from its battery.Size on continuous AC watts, not watt-hours. A UK socket is BS 1363, rated 13 A at 250 V, so a plug-in appliance tops out at about 2,990 W at 230 V, and every UK plug carries its own fuse. That is why the standard British kettle is 3 kW: it sits right at the top of the design envelope. It is also above the continuous output of almost every portable power station sold, which stop at 1,800 to 2,400 W with only flagship units reaching 3,000 W. Check the station's continuous AC rating against 3,000 W before you plan around a kettle, and keep a 2.2 kW or travel kettle for off-grid.Every 110 V site transformer ships on a 13 A BS 1363 plug with a 2 m lead, so whatever the kVA badge says the 230 V input can never exceed about 3 kW. A "5 kVA" transformer on a 13 A plug is input-limited to roughly 3 kW and is rated only 2.8 kVA continuous in any case. Size a power station against the transformer's continuous rating, not its intermittent one.Power stations cannot be flown. The CAA allows lithium batteries up to 100 Wh in the cabin without approval, 100 to 160 Wh with the airline's approval in advance, and prohibits anything over 160 Wh in passenger baggage entirely. Every power station on this page is 288 Wh or more. Power banks, spare batteries and vapes must be carried in the cabin and never in hold baggage, at most two power banks per person, not recharged on board, with spares individually protected against short circuit.

    How it works

    Method and assumptions

    Every appliance is energy over time: watts multiplied by hours. The 230 V figures here are the Centre for Sustainable Energy's and Electrical Safety First's published appliance ratings, which is the closest thing the UK has to an official wattage table. Fridges and freezers do not draw their rated watts all day because the compressor cycles, and a 12 V compressor fridge is lower again: Dometic's own figure for a 45 L unit at 32 °C is about 12 W on average, or 300 Wh a day.

    Power stations lose energy turning battery into 230 V AC, about 15%, and the battery management keeps a reserve, so about 90% of the rated capacity is usable. The calculator divides AC loads by the inverter efficiency and DC loads (12 V socket or USB) by a much smaller loss, then compares the result with each pick's usable capacity and inverter rating. In the UK the inverter rating is usually what stops you, not the capacity: a 3 kW kettle only uses about 150 to 180 Wh per boil, but it wants 3,000 W while it does it, and most portable stations stop at 1,800 to 2,400 W.

    Solar recharge uses NASA POWER peak sun hours for your nearest city, a 20-year monthly mean, and derates a portable panel to 75% of its sticker rating, which is what EcoFlow itself suggests planning on. Read the winter column before you plan around solar: London averages 0.66 peak sun hours in December against 2.94 across the year, and Glasgow 0.37. Cloud, a flat panel and short days push it lower still; a panel tilted at the sun does better.

    Appliance figures are manufacturer specifications or published measurements where available and clearly marked estimates elsewhere; your model may differ, so check its label. Runtimes are estimates, not a guarantee. For medical devices such as CPAP or oxygen concentrators, size with the manufacturer's own figures and keep a margin.

    Power Station Calculator — Frequently Asked Questions

    Will a power station boil a 3 kW kettle?+

    Only the biggest ones. A standard UK kettle is 3,000 W, which is the top of what a 13 A socket delivers, and that is above the continuous AC output of almost every portable power station sold: most stop at 1,800 to 2,400 W and only flagship units reach 3,000 W or more. Capacity is not the problem, because a boil is only about 150 to 180 Wh. Check the continuous AC watts on the specification, not the watt-hours, and keep a 2.2 kW or travel kettle for the power station.

    Can a power station run a tumble dryer?+

    A heat pump dryer, yes. A vented or condenser dryer, no. Electrical Safety First rates a heat pump tumble dryer at 800 W and 3.5 A, and measurements put it at 400 to 500 W once it is up to speed and 0.8 to 1.2 kWh for a whole cycle, so a 2 kWh station will finish a load. A vented or condenser dryer is 2,500 W and 3.5 to 5.3 kWh a cycle, which beats most inverters on output and every portable station on capacity.

    How long will a power station run a fridge?+

    A UK household fridge is about 150 W while the compressor runs and a fridge-freezer about 300 W, but neither runs continuously, so plan on roughly 1 to 1.5 kWh a day for a full-size fridge-freezer. A 12 V compressor camping fridge is far cheaper to run: Dometic rates a 45 L CFX3 at 12.4 W average in 32 °C heat, about 300 Wh a day, so a 1,000 Wh station on the 12 V socket lasts close to three days.

    What size power station do I need for a CPAP?+

    ResMed's battery guide puts an AirSense 10 without humidifier at 0.7 to 1.7 A at 12 V, so a night is about 90 Wh and a 288 Wh station covers two or three nights. With the heated humidifier and tube it rises to 4.7 to 5.6 A, close to 60 W or 480 Wh a night, so plan on 1,000 Wh for two nights and use the DC converter, not the inverter.

    What can I run on a 6 A campsite hook-up?+

    About 1,380 W, which is a fridge, a charger, a TV and a low-wattage kettle, and not much else at once. Sites run by the Camping and Caravanning Club are usually 10 A (2,300 W) or 16 A (3,680 W), but smaller and rural sites are often 6 A only, and every bollard has its own MCB and RCD. The Club warns against ordinary domestic kettles on hook-up for exactly this reason: a 3 kW kettle draws 13 A on its own.

    How long does it take to recharge from solar in the UK?+

    Divide the energy you used by the panel's real output, then by the peak sun hours for the month you are in. A 200 W portable panel makes about 150 W in good sun, so 700 Wh needs about 4.7 hours of full sun. London averages 5.30 peak sun hours in June, so that is a long summer morning, and 0.66 in December, so the same recharge takes the best part of a week. UK winter solar is close to useless for anything but topping up.

    Can I take a power station on a plane?+

    No. The CAA allows lithium batteries up to 100 Wh in the cabin without approval and 100 to 160 Wh with the airline's approval in advance; anything over 160 Wh is prohibited in passenger baggage altogether. Every power station on this site is 288 Wh or more, so they travel by road. Power banks and spare batteries must go in the cabin, never in hold baggage, two per person, and must not be charged on board.

    What is the difference between Wh and Ah?+

    Amp-hours only mean something with a voltage attached. A 100 Ah 12 V battery holds 1,200 Wh; a 100 Ah 24 V battery holds twice that. Power stations quote Wh so you can compare them directly; to convert a 12 V fridge's amp draw, multiply by 12.

    Useful? Send it to the mate who keeps asking.

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