Running Watts vs Starting Watts
By OutageMath · Updated September 24, 2026
Your power station has plenty of battery left, yet it shuts off the moment your fridge kicks on. The culprit is almost always starting watts, the short spike a motor needs to get moving.
Two numbers for every appliance
Running watts are what a device draws while it's working. Starting watts (also called surge or peak watts) are the brief spike when an electric motor or compressor starts from standstill. It lasts a fraction of a second to a few seconds, but it can be several times the running figure.
Heating devices such as kettles, toasters, space heaters and coffee makers have no motor, so their starting and running watts are the same.
| Appliance | Running | Starting | Ratio |
|---|---|---|---|
| Refrigerator (full-size, ENERGY STAR) | 150 W | 1,200 W | 8× |
| Chest freezer (7–15 cu ft) | 100 W | 800 W | 8× |
| Window AC (5,000 BTU) | 450 W | 1,100 W | 2.4× |
| Sump pump (1/2 HP) | 1,050 W | 2,150 W | 2× |
| Well pump (1/2 HP submersible) | 800 W | 2,000 W | 2.5× |
| Gas furnace blower fan | 600 W | 1,400 W | 2.3× |
| Circular saw (7-1/4 in.) | 1,400 W | 2,300 W | 1.6× |
| Microwave (1,000 W cooking power) | 1,500 W | 1,500 W | 1× |
| Space heater (portable, 1,500 W) | 1,500 W | 1,500 W | 1× |
| Drip coffee maker (10–12 cup) | 1,000 W | 1,000 W | 1× |
Typical values from generator makers' wattage charts, ENERGY STAR and manufacturer data. See the full appliance wattage chart.
What a power station's surge rating means
Every power station lists a continuous output (what it can supply indefinitely) and usually a surge or peak output (what it can supply for a moment). To run a device, both must be high enough:
- Continuous output ≥ the running watts of everything on at once.
- Surge output ≥ everything running plus the extra starting power of the motor that's starting.
How long a station can hold its surge rating varies, and most manufacturers don't say. A few do. For example, Jackery says the Explorer 1500 Ultra peaks at 3,600 W for 5 seconds. So when a device's starting watts are close to the surge rating, treat it as a maybe.
“Boost” modes aren't surge
Boost modes such as EcoFlow's X-Boost, BLUETTI's Power Lifting and similar features let a station run some heating devices rated above its output, typically by lowering the voltage. That works for simple resistive loads like kettles and hair dryers, which just run at lower power. It doesn't help motors start, and it can stop electronics from working properly.
How to find your appliance's starting watts
- Check the manual or spec sheet. Some list “starting” or “surge” watts directly.
- Look for LRA on compressor labels. Locked rotor amps × 120 V gives an upper bound for the starting spike of fridges and AC units.
- Use a generator wattage chart for typical values, like the ones behind our appliance chart.
- Measure it. Clamp meters with an inrush function capture the real spike.
Practical tips
- Start the big motor first, then plug in everything else.
- Don't run two motor loads that may start together, like a fridge and a sump pump, on a station near its surge limit.
- Newer, variable-speed (“inverter”) fridges and ACs typically start more gently.
- The runtime calculator checks surge for your whole device list.