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Portable power station calculator for camping
Pick what you run. You get a daily watt-hour target, the gross capacity to shop for, and a realistic solar yield - with every constant behind the number published below.
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Sizing calculator
Pick the plain-English preset that matches your setup. Each preset already assumes a realistic appliance wattage; you only need to think about what you run and for how many nights.
Why the number is bigger than the sticker
A 1,000 Wh station does not give you 1,000 Wh. Four things take a slice between the cell and the appliance, and manufacturer calculators tend not to show any of them. Here is the whole chain on a nominal 1,000 Wh LiFePO4 unit:
- Gross capacity, 1,000 Wh. The number on the box, measured at the cells.
- Usable depth of discharge, ~900 Wh. The battery-management system reserves headroom at both ends and the inverter draws a little just being switched on. Datasheets put usable LiFePO4 capacity at 90-95 percent; we plan on 90.
- Inverter conversion, ~765-810 Wh of AC. Anything you run from the household socket loses roughly 10-15 percent on the way through. DC loads - a 12V fridge on the car socket, USB charging - skip this step entirely, which is why running the fridge on DC is worth doing.
- Cold, less again. Usable capacity falls as cells approach freezing, and most packs will not charge below 0°C without an internal heater. There is no single honest percentage here because it depends on the pack and the night, which is why our advice for winter is to size up a band rather than apply a factor.
The calculator returns gross watt-hours, with the 90 percent usable factor and a 25 percent planning margin already applied, so the figure it gives you is the one to type into a retailer's filter.
Three worked examples
Same arithmetic as the tool, shown in full. If your setup is close to one of these you can sanity-check the calculator against it.
Weekend, fridge and fan, no solar
60 L fridge, roof fan overnight, interior LEDs, phones and one laptop, two nights, no panel.
- Fridge: 480 Wh/day
- Fan: 200 Wh/day
- Lights: 40 Wh/day
- Devices: 80 Wh/day
- Daily total: 800 Wh
- Over 2 nights: 1600 Wh ÷ 0.9 × 1.25 = ~2222 Wh gross
Week-long base camp with induction cooking
75 L fridge in hot weather, roof fan, LEDs, phones and one laptop, induction hob, seven nights, 200 W panel.
- Fridge: 720 Wh/day
- Fan: 200 Wh/day
- Lights: 40 Wh/day
- Devices: 80 Wh/day
- Cooking: 1200 Wh/day
- Daily total: 2240 Wh
- Less solar at 630 Wh/day: 1610 Wh/day from the battery
- Over 7 nights: 11270 Wh ÷ 0.9 × 1.25 = ~15653 Wh gross
Laptop-only weekend, no fridge
No fridge, small clip fan in the evening, head torch, phones and one laptop, two nights, no panel.
- Fan: 60 Wh/day
- Lights: 15 Wh/day
- Devices: 80 Wh/day
- Daily total: 155 Wh
- Over 2 nights: 310 Wh ÷ 0.9 × 1.25 = ~431 Wh gross
Using a camping station for a home outage
Switch the calculator to outage mode and it answers in hours of coverage rather than nights, using a narrow load set: the fridge, a Wi-Fi router, phone charging, and a few lights. Three things differ from camping, and all three make the honest answer shorter than people expect.
- No solar recharge. The panel is in the garage, and an outage is often a storm. Plan the whole event on stored energy.
- Compressor startup surge. A domestic fridge draws several times its running wattage for the fraction of a second the compressor kicks in. Check the station's surge rating, not just its continuous output, before assuming a 300 W inverter will hold a 120 W fridge.
- It is not medical backup. A camping power station is not a substitute for the backup a CPAP, oxygen concentrator, or refrigerated medication requires. Follow the device manufacturer's guidance for those, not a camping calculator.
For the hardware itself, the same units apply: see stations in the 1,000-1,500 Wh band .
What the verdict band means
- Small (< 500 Wh): phone, lights, laptop weekends. No fridge.
- Mid (500-1,500 Wh): the camping sweet spot - fridge + fan + laptop for 2-4 nights.
- Large (1,500-3,600 Wh): week-long base camp, induction cooking, partial home backup.
- Dual-battery LiFePO4 build: daily draw above 2,000 Wh sustained or permanent install territory.
How the calculator works
The math is the same one we walk through in what size power station you need for camping. The calculator just runs it in your browser:
- Daily Wh need = sum of (fridge running watts * 24 hours * duty cycle) + (fan/lights watts * hours/day) + (devices Wh per charge * charges/day) + cooking Wh/day.
- Daily solar yield = panel rated watts * effective sun hours (default 4.5) * real-world loss factor (default 0.7).
- Required usable energy from battery = (daily Wh need - daily solar yield) * trip days, with a floor of zero (excess solar does not reduce the bank).
- Required gross battery capacity = required usable energy / 0.9 (LiFePO4 usable depth-of-discharge) * 1.25 (cloudy-day / inverter-loss margin).
What this tool cannot know
The calculator does not know your exact ambient temperature, your panel angle, your shade pattern, your appliance condition, or the recharge sources available at your specific sites. Use it to land in the right capacity band, then verify with a Kill-A-Watt on the appliances you actually own. Real-world variance is wide; sizing to the middle of the recommended band leaves you headroom for the bad-weather days.
Assumptions
Every constant this calculator applies
Published so you can audit the output instead of trusting it. Change any of these in your own head and the recommendation moves accordingly. How we build these numbers .
- Usable depth of discharge: 90% of gross capacity
- LiFePO4 cells tolerate deep cycling, but battery-management cutoffs and the inverter's own idle draw mean you do not get the sticker number. Manufacturer datasheets put usable capacity at 90-95%; we take the low end.
- Planning margin: +25% on required capacity
- Covers cloudy days, inverter conversion loss, and colder-than-expected nights in one factor rather than three guesses. It is a planning cushion, not a measured figure.
- Effective sun hours: 4.5 hours per day
- A mid-range figure for the continental US in summer. NREL PVWatts will give a better number for your latitude, month, and panel tilt - use it if you are sizing an array rather than a station.
- Real-world solar yield: 70% of rated panel watts
- EcoFlow publishes 70-75% of rated output under typical conditions once angle, temperature, cable loss, and charge-controller efficiency are counted. We use 70%.
- Inverter loss: Folded into the 25% margin
- AC output through an inverter typically costs 10-15% versus running the same load on DC. We do not model it separately because the loss depends on how much of your load is AC, which the calculator cannot know.
- Cold-weather penalty: Folded into the 25% margin
- LiFePO4 loses usable capacity below roughly 0C and most packs refuse to charge below freezing. If you camp in genuine winter, size up a band rather than relying on this margin.
Common questions
How many watt-hours do I actually need per day?
Add the watt-hours each appliance consumes over 24 hours. A 60 L compressor fridge at 50 W running roughly 40 percent of the time is about 480 Wh. A roof fan at 25 W for eight hours is 200 Wh. A laptop charge is around 80 Wh. Most vehicle campers running a fridge, a fan, lights, and phones land between 600 and 900 Wh a day.
Why won't a 1,000 Wh station deliver 1,000 Wh?
The rated figure is gross cell capacity. Battery-management cutoffs and the inverter's own idle draw take a slice, so plan on about 90 percent of the sticker. Running AC loads through the inverter costs another 10 to 15 percent versus the same load on DC, and capacity falls further below freezing. A 1,000 Wh station realistically delivers 800 to 900 Wh of useful energy in mild weather.
How much solar do I need to break even each day?
Divide your daily watt-hour need by about 3.15, which is 4.5 effective sun hours at 70 percent of rated panel output. A 700 Wh daily load needs roughly 220 W of panel to break even on a clear summer day, and it will not break even in shade, in winter, or with the panel flat on a roof.
Does cold weather change the answer?
Yes. LiFePO4 loses usable capacity as temperatures approach freezing, and most packs refuse to charge below 0 C without an internal heater. The fridge also works less in the cold, which partly offsets it. If you camp in genuine winter, size up one capacity band rather than relying on the 25 percent margin this calculator applies.
When should I stop buying portable stations and build a dual-battery system?
Roughly when sustained daily draw passes 2,000 Wh, or when you would need to buy a third portable unit. At that point a permanent LiFePO4 house battery with a DC-DC charger is usually cheaper per usable watt-hour, recharges from the alternator while you drive, and does not have to be carried.
Can I use this to size a station for a home power outage?
For a narrow set of loads, yes. Switch the calculator to outage mode and it reports hours of coverage instead of nights. It is not a whole-house backup planner, and it must not be used to size backup for a medical device, a sump pump, or a well pump. For medical equipment, follow the device manufacturer's own backup guidance.
Sources
Where the appliance and solar numbers come from
Manufacturer datasheets for compressor draw and fan wattage; NREL PVWatts for effective sun hours; LiFePO4 datasheets for usable depth-of-discharge.
- [1] Dometic CFX3 compressor fridge specifications Source for compressor wattage and duty-cycle ranges on 35L, 55L, and 75L 12V fridges.
- [2] MaxxAir Maxxfan Deluxe specifications Source for fan wattage at low, medium, and high speeds.
- [3] NREL PVWatts solar production calculator Independent reference for effective sun hours by latitude and panel orientation.
- [4] EcoFlow blog: real solar panel output Manufacturer-published efficiency factor (70-75 percent of rated panel watts) under typical conditions.
- [5] Battle Born / Renogy LiFePO4 datasheets Reference for LiFePO4 usable depth-of-discharge (90-95 percent of gross capacity).