Power station runtime calculator

How is runtime calculated?

Runtime in hours = battery capacity in Wh × 0.85 ÷ the average watts of everything running.

Worked example: a 1,024 Wh station running a full-size fridge (200 W, on about a third of the time, so about 66 W on average) and a 20 W router draws about 86 W on average. 1,024 × 0.85 ÷ 86 ≈ 10.1 hours. The station also has to start the fridge's compressor, so its surge rating must cover the compressor's start-up draw plus everything already running.

How do you use the runtime calculator?

Pick a station, add everything that will run at the same time, then correct each row's watts and quantity. The result updates as you type.

1. Pick a power station from the 56 current models.
2. Add your loads from the 49 appliances in the list.
3. Edit watts and quantity to match your own labels, such as two lamps or three phones.
4. Read the result. The big number is runtime from a full charge. The running chip compares everything switched on with the continuous rating. The start-up chip compares the worst start-up moment with the surge rating.

How long do common appliances run on different-sized stations?

A small station runs a router or laptop for most of a day, while heaters and air conditioners drain even the largest units in hours. Each load below runs on its own.

"Can't run" means the draw is above the station's continuous rating, so no amount of battery helps. A bigger battery adds hours; only a bigger inverter runs a bigger load. Each appliance has its own page, such as which power stations can run a refrigerator.

What size station does a work-from-home day need?

An eight-hour workday on a desktop, router and two lights needs about 2,899 Wh of battery.

The peak is only 308 W, so capacity is the limit. 14 models hold a full day, and the smallest is the BLUETTI Elite 300 at 3,014 Wh, in the 3,000 Wh and up size group. A laptop in place of the desktop shrinks the need sharply.

What size station does a van day need?

A day with a 12 V fridge, a Starlink Mini, a laptop and phones needs about 898 Wh. The fridge runs all day but only part of the time.

43 models hold that, and the smallest is the BLUETTI Pioneer Na at 900 Wh. That leaves almost no margin for a cloudy day, so check the solar recharge calculator or the best power stations for van life.

Why do some appliances use a duty cycle and others count as always on?

Fridges and freezers cycle their compressor, so 3 appliances use a cited duty cycle. Everything else counts as running nonstop at full rating, which makes most results a worst case. A laptop doing light work is a good example: the median ENERGY STAR laptop idles far below its charger rating. (ENERGY STAR Certified Computers V9.0 (dataset), ENERGY STAR, 2026) For a load used part of the day, you can enter reduced watts as a rough average, but the chips will then understate its peak.

What do "Too much load" and a red start-up chip mean?

"Too much load" means your loads add up to more running watts than the continuous rating. Remove one, pick a model with a larger inverter, or run the big appliance alone.

A red start-up chip means the running total plus the largest single surge exceeds the surge rating. The calculator assumes one motor starts at a time, so a fridge and freezer starting together peak higher. A compressor can pull several times its running current for an instant. (Technical Data Sheet B60C5BL R600a 110-120V 60Hz, Danfoss, 2020) Where no surge figure is published, the chip uses the continuous rating; 50 of 56 models publish one. See surge vs running watts for staggering starts.

How do you find the watts of your own appliance?

Read the input watts on the label, or multiply volts by amps: 120 V at 2 A is 240 W at most. Advertised wattage can mislead. A microwave sold by cooking power draws more from the outlet. (Features and Specifications - Microwave Oven - NN-SU696SAWH, Panasonic North America, 2026) Internet gear varies too: a provider's combined modem and router can draw several times what a plain router does, so look up your model. (Comcast SNE Energy Information (CableLabs Energy Reporting), Comcast / CableLabs, 2026) A plug-in energy meter gives the best average for loads that cycle.

Do USB and 12 V loads drain the battery differently from AC?

Yes. A phone, laptop or 12 V fridge on a USB-C or car port skips the inverter, so the inverter loss built into the calculator's 85% efficiency doesn't apply to it. Port limits still apply: a Starlink Mini needs a strong enough USB-C port to run at all. (Starlink Mini Specification Sheet, SpaceX / Starlink, 2026)

What can't the calculator know about your setup?

It can't see battery age, temperature or the station's own idle draw. An older battery holds less, cold cuts usable capacity, and heat wears some chemistries faster, as the battery chemistry guide explains. Results also assume a full charge and every load you added. Leave a generous margin, and read how we research our numbers.