Running Watts vs Starting Watts

By Hicham M. · Updated October 11, 2026

Your power station has plenty of battery left, yet it shuts off the moment your fridge kicks on. Usually that’s 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.

How many times? Honda says motors in fridges, pumps and air conditioners “can draw up to three times their running load for a few seconds”, and Jackery’s manual says the same about inductive loads. Generac, which sizes generators for a living, puts single-phase induction motors at 3 to 5 times. Anker describes the spike as lasting roughly one second. Some loads go well past those rules of thumb: the generator wattage charts we use list a fridge at 1,200 W to start against 150 W running, and Franklin Electric’s figures for a 1/2 HP well pump work out to more than six times.

Heating devices such as kettles, toasters, space heaters and coffee makers have no motor, so their starting and running watts are the same.

Typical running and starting watts
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	5,300 W	6.6×
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.
Read the motor’s code letter. Motor nameplates carry a NEMA code letter for starting kVA per horsepower; later letters mean a harder start. Generac’s sizing guide calls code G (5.6 to 6.3 kVA per HP) the most common among three-phase industrial motors. Small single-phase motors sit much higher: Franklin’s 1/2 HP well-pump motors are code M (3-wire) and code R (2-wire).
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.
A soft starter can tame an air conditioner. Micro-Air says its EasyStart Flex cuts startup current by up to 75%; it’s sold for generators and inverters, so check compatibility with your station.
The runtime calculator checks surge for your whole device list.

Running Watts vs Starting Watts

Two numbers for every appliance

What a power station's surge rating means

“Boost” modes aren't surge

How to find your appliance's starting watts

Practical tips

Sources

Keep reading

Calculators

Runtime calculator

What size do I need?

Solar charging calculator

Generator vs power station

Compare models