Tool
How big a power station do you need?
The runtime tables on this site answer one appliance at a time. This answers your list: what must stay on, for how long, and whether a solar panel or a vehicle can top the battery up each day. Every wattage is from a maker's spec sheet or an ENERGY STAR listing, and the answer is a class with a link to the page that ranks it, never a product.
Sizing calculator
What must stay on, for how long, and can you recharge?
Every wattage below is from a maker's spec sheet or an ENERGY STAR listing. Start from a household or tick your own list; the answer is a class, a link to the page that ranks it, and the arithmetic.
Tick an appliance, or tap a household above, and the answer appears here.
How the number is built
For each appliance, running watts times the share of each hour it actually runs (the duty cycle) times hours a day gives watt-hours a day at the outlet. Days multiply it. The total is divided by the inverter efficiency, 85% unless you change it, because a battery's watt-hours become outlet watt-hours through an inverter that loses roughly that much. The result is usable battery, the same unit as the columns on every runtime table here, so a 2,600 Wh answer reads straight across to the 2 kWh and 4 kWh columns on the sump pump page.
How a recharge changes it
Over one day, a recharge does not enter: the battery has to hold the day. Over two or three, it does. Solar is counted at 75% of the panel's label, which is EcoFlow's own planning figure, times the hours of strong sun you choose; a vehicle's 12 V socket is counted at about 96 W, the figure on EcoFlow's and Bluetti's spec pages; a generator or returning grid power is a full refill. The daily shortfall, use minus recharge, is multiplied by the days, and the battery must also hold one full day before the first recharge arrives, so the answer is the larger of the two. The solar guide covers the panel figure and the unit's input ceiling, which caps how fast any amount of panel can refill it.
What it deliberately does not do
- Guess a start-up spike. Where a maker publishes a locked-rotor figure, as Franklin does for its well pump motors, the calculator uses it. Where a motor's maker publishes nothing, as refrigerator and most sump pump makers do not, it applies this site's stated margin rule of a 3,000 W surge rating and says so, rather than inventing a multiplier. The reasoning is in running versus surge watts.
- Recommend a product. The answer is a class and a link to the page that ranks that class with sourced specs. A calculator that landed on one unit would be a sales funnel.
- Pretend a heater is fine. The battery killers are in the list on purpose. Tick one and the answer shows what it costs and what you need without it, because "do not buy a battery for this" is the most useful sentence on the space heater page.
- Hide the assumptions. Duty cycle, hours and efficiency are all editable, and the arithmetic is printed under the answer.
If the answer is whole-home class
Above about 8 kWh a day, or with a 240 V load like a well pump or a central air conditioner on the list, the honest answer is an installed system sized with a licensed electrician. The whole-house page explains what that involves and what to ask.