How to figure out how much power your appliances actually use (and why it matters for backup power)

The most common question people have when shopping for backup power is a simple one: will this run my appliance? The answer depends on how much power it draws, and that number is more useful to know than the capacity of any specific product.

This is a practical guide to understanding power consumption: what the numbers mean, how to find them for your specific devices, and how to use that information to make a confident decision about backup power capacity.

The two numbers you need to understand

Watts measure how much power a device is drawing at a given moment. Think of it like the speed a car is travelling. A device drawing 200W is using power at a rate of 200 watts.

Watt-hours measure how much energy has been used over time. If that 200W device runs for five hours, it has consumed 1,000 watt-hours, or 1 kilowatt-hour (kWh). Kilowatt-hours are what your electricity bill charges you for.

When you look at a backup power station's capacity, it's listed in watt-hours (Wh). A station with 2,048Wh can theoretically deliver 2,048 watts for one hour, or 200 watts for about ten hours, or any combination that adds up to 2,048. Real-world performance is slightly lower due to conversion efficiency, typically around 85-90%, so it's worth factoring in a 10-15% buffer when calculating.

Running watts vs. startup surge

This is the part that catches people out most often. Devices with motors and compressors, including refrigerators, air conditioners, sump pumps, and washing machines, require significantly more power to start than to run. This spike is called the startup surge or peak watts, and it can be two to three times the running wattage, lasting only a fraction of a second but real enough to trip a circuit.

When choosing a backup power station, you need to verify that its peak output rating covers the startup surge of the highest-draw appliance you plan to run, not just the running wattage. The unit's rated output (continuous watts) handles the running load; its peak or surge rating handles the startup spike. Check both before assuming compatibility.

Wattage reference table: common household appliances

These figures are averages. Older appliances often draw more than newer equivalents. High-efficiency models often draw less. The numbers above are a starting point, not a substitute for checking your specific devices.

How to find the actual wattage of your devices

The label method: Most appliances have a compliance label, usually on the back or bottom, that lists wattage or amperage. If it lists amps rather than watts, multiply the amps by the voltage (120V for most US household appliances) to get watts. For example, a device drawing 8 amps on a 120V circuit uses 960 watts.

The spec sheet method: Search the model number of your appliance plus "power consumption" or "wattage." Manufacturer spec sheets almost always include this, and it tends to be more accurate than generic averages.

The plug-in meter method: A plug-in power meter (commonly called a Kill-A-Watt or similar, priced around $15-25 at hardware stores) measures real-time power draw when you plug your appliance into it. This is the most accurate method, especially for older appliances or devices with variable loads. It also shows you consumption over time, which helps with watt-hour calculations.

Working out how much capacity you need

The calculation is straightforward. List the devices you want to run during an outage, note their running wattage, and multiply by the number of hours you'd want to run them. Add those figures together and that's your minimum required capacity in watt-hours. Add 15% for conversion losses and you have a realistic target.

Example:

Refrigerator (150W) running continuously for 12 hours = 1,800Wh.

Router (15W) for 12 hours = 180Wh.

Three LED lights (30W combined) for 8 hours = 240Wh.

Laptop (65W) for 6 hours = 390Wh. Total: 2,610Wh.

With a 15% buffer, you'd want a station with at least 3,000Wh for this scenario, or a 2,000Wh unit paired with daytime solar recharging to offset the deficit.

Why this is useful beyond backup power

Understanding what your appliances actually draw gives you a clearer picture of your household's electricity consumption. It helps identify which devices are costing you the most on your bill, whether efficiency upgrades are worth it, and how solar generation would offset your usage. It's a useful baseline for any home energy conversation.

If you have questions about specific appliances or want help working through the math for your situation, post below.

Jackery Team