⚡ Power Station Runtime Calculator Pro
Runtime, days of backup, solar recharge, surge check and the right station size, in one place.
Your power station
Devices
Untick a device to exclude it| On | Device | Watts | Qty | Hrs/day | Surge W | Daily Wh |
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Recharging & planning
Output check
Where your energy goes
Daily Wh from batteryCompare station sizes
Same devices & settings| Size | Continuous | Days | Backup |
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Portable Power Station Runtime Calculator: How Long Will It Really Last?
Enter your station's watt-hours and the devices you plan to run. Get a realistic runtime in seconds, then learn the formula, the hidden losses, and how to stretch every last watt.
Portable Power Station Runtime Calculator
Add each device you want to power, adjust quantities, and the calculator updates instantly. Use the wattage on your device's label or charger; for appliances that cycle on and off (fridges, freezers), use the average draw, which the presets already do.
1. Your power station
2. Your devices
| Device | Watts | Qty | Total |
|---|
3. Your estimated runtime
How Power Station Runtime Is Calculated
Every runtime calculator, including the one above, rests on one simple idea: a battery stores a fixed amount of energy (watt-hours), and your devices use energy at a certain rate (watts). Divide one by the other and you get hours. The only extra step is subtracting the energy lost along the way.
Step 1: Find capacity (Wh)
Look for "Wh" on the label. If only amp-hours are listed, convert with Wh = Ah × Volts. A 100 Ah, 12.8 V battery stores 1,280 Wh.
Step 2: Add up the watts
Total every device you'll run at the same time. Two 10 W LED lamps plus a 65 W laptop = 85 W of load.
Step 3: Apply efficiency
Multiply capacity by 0.85 for AC outlets or about 0.92 for DC/USB ports. This covers inverter and conversion losses.
Step 4: Divide
Usable Wh ÷ total watts = hours. 850 Wh ÷ 85 W = 10 hours of runtime.
Runtime Chart: How Long a 1,000 Wh Power Station Runs Common Devices
The 1,000 Wh class is the most popular size for home backup and camping. Here's how long one lasts on a single device using AC power at 85% efficiency (850 usable Wh). For other sizes, scale proportionally: a 500 Wh unit gives half these times, a 2,000 Wh unit gives double.
| Device | Typical Watts | Runtime | Relative runtime |
|---|---|---|---|
| LED light bulb | 10 W | ~85 h | |
| Wi-Fi router / modem | 12 W | ~71 h | |
| Phone charging | 18 W | ~47 h (≈50+ full charges) | |
| CPAP (no humidifier) | 40 W | ~21 h (2–3 nights) | |
| Mini fridge / 12V cooler (avg) | 45 W | ~19 h | |
| Box fan | 50 W | ~17 h | |
| Full-size fridge (avg) | 60 W | ~14 h | |
| Laptop | 65 W | ~13 h | |
| Satellite internet dish | 75 W | ~11 h | |
| 55" LED TV | 100 W | ~8.5 h | |
| Desktop PC + monitor | 250 W | ~3.4 h | |
| Coffee maker | 1,000 W | ~51 min | |
| Microwave (input draw) | 1,200 W | ~42 min | |
| Space heater / kettle | 1,500 W | ~34 min |
Wattages are typical averages. Check your own device's label, since a microwave rated "1,000 W cooking power" usually pulls 1,400–1,500 W from the outlet.
Which Size Do You Need? Runtime by Station Capacity
A refrigerator is the device most people want to keep running in an outage, so it makes a good benchmark. This table assumes a modern fridge averaging 60 W over time (about 1.4 kWh per day) on AC power.
| Station Size | Usable Wh (85%) | Fridge Runtime | Coverage |
|---|---|---|---|
| 300 Wh | 255 Wh | ~4 h | |
| 500 Wh | 425 Wh | ~7 h | |
| 1,000 Wh | 850 Wh | ~14 h | |
| 2,000 Wh | 1,700 Wh | ~28 h | |
| 3,000 Wh | 2,550 Wh | ~42 h | |
| 5,000 Wh | 4,250 Wh | ~71 h (3 days) |
Camping & day trips
250–700 Wh. Phones, lights, a fan, a CPAP for one night, a 12V cooler for part of the day.
Van life & RV weekends
1,000–2,000 Wh. Laptops, fridge, lights, and brief use of a kettle or induction plate. Pair with solar.
Home backup
2,000–5,000+ Wh. Fridge, router, lights, phones and medical devices through a 1–3 day outage, longer with solar or expansion batteries.
7 Things That Make Real Runtime Shorter Than the Math
If your station dies earlier than the calculator predicted, one of these is almost always the reason.
Inverter losses
Turning DC battery power into 120 V AC typically loses 10–15% as heat. That's why we use 0.85 as the default multiplier.
Idle (no-load) draw
The inverter itself consumes power just by being on, often 10–30 W depending on the unit. On tiny loads like a phone charger, this can halve your runtime.
Cold temperatures
Lithium batteries deliver noticeably less capacity near or below freezing. Keep the station indoors or insulated in winter.
Battery age
Capacity fades with cycles. An older NMC unit may hold well under its original rating; LiFePO4 fades far more slowly.
Cycling appliances
Fridges, freezers and pumps switch on and off. Using the label's peak wattage underestimates runtime; using too low an average overestimates it.
Startup surge
Motors and compressors briefly pull 2–3× their running watts. It doesn't drain much energy, but it can trip a station whose surge rating is too low.
Low-battery cutoff
Many stations shut off a few percent before reaching true zero to protect the cells, and some apps let you set a higher discharge limit.
LiFePO4 vs. NMC: Does Battery Chemistry Change Runtime?
On a single charge, a 1,000 Wh LiFePO4 station and a 1,000 Wh NMC station run a device for roughly the same time. The difference shows up over years of use.
🟢 LiFePO4 (LFP)
- Typically rated for 3,000+ cycles to 80% capacity
- Holds its runtime for many years of daily use
- More thermally stable and safer
- Heavier and bulkier per Wh
🔵 NMC (Lithium-ion)
- Typically 500–1,000 cycles to 80% capacity
- Runtime shrinks faster with regular use
- Lighter and more compact
- Common in older and ultra-portable models
How to Get More Runtime From Your Power Station
Use DC and USB ports whenever possible
Charging phones and laptops through USB-C, or running a 12V fridge from the car port, skips the inverter and can add 5–10% more runtime.
Switch the AC inverter off when you're not using it
An idle inverter quietly burns watts all night. If only USB devices are plugged in, turn AC off.
Turn on ECO or energy-saving mode
Most stations can auto-shut the AC output when the load drops below a threshold, which prevents slow overnight drain.
Keep the fridge closed and full
A packed fridge holds cold longer and the compressor runs less often, lowering the average wattage you're paying for.
Choose low-watt alternatives
An electric blanket (50–100 W) uses a fraction of a space heater's 1,500 W. LED bulbs beat any other lighting by far.
Disable the CPAP heated humidifier
The humidifier can double or triple a CPAP's power draw. Running it dry (or on a low setting) can stretch one charge across several nights.
Recharge with solar during the day
A rough daily solar estimate is panel watts × peak sun hours × 0.75. A 200 W panel in 5 sun hours adds about 750 Wh, nearly a full 1,000 Wh station.
Store it charged, cool and topped up
Keep the battery around 60–80% in storage and top it off every few months so it's full and healthy when the power actually goes out.
Frequently Asked Questions
How long will a 1,000 Wh power station run a refrigerator?
Can a portable power station run a CPAP overnight?
How do I convert mAh or Ah to watt-hours?
Why did my power station run out faster than the calculator said?
Can a power station run a space heater?
Does using the DC or USB ports really extend runtime?
How long does it take to recharge a power station?
Can I use my power station while it's charging?
Know Your Numbers Before the Lights Go Out
Run your real devices through the calculator above, add a 20% safety margin, and you'll know exactly which station size keeps your home, campsite or van running.