Refrigerator Generator Size Calculator

What generator keeps your fridge alive in an outage?

Size a backup generator to keep your fridge, freezer, and essentials running. Accounts for compressor surge wattage (typically 3× running watts) plus a 20% safety margin per portable-generator manufacturer guidance.

⏱ ~30 sec•Compressor surge × 1.2 margin•Installation & Setup

3×

Surge

Single-speed compressor

20%

Margin

Safety buffer

2,000W

Practical min

Fridge only

5,000W

Fridge + freezer

+ essentials

STEP 01

Five inputs.
Real generator size.

Sum running watts. Multiply each compressor by 3× for surge. Add 20% safety margin.

Fridge running watts

From the inside-cabinet nameplate.

Freezer running watts

Essential LED lights (+100W)Window AC unit (+1,200W run / +3,600W surge)Well pump (+1,000W run / +3,000W surge)

Updates live as you type

Recommended generator

5,000W

3,500–5,000W portable

Running watts

1,300

Starting watts

3,700

Under the hood

Surge watts. Safety margin.

Compressor surge multipliers come from manufacturer spec sheets (3× for single-speed). The 20% margin matches portable-generator manufacturer guidance to prevent overload trips.

01
Sum running watts
Add fridge + freezer + each enabled essential. This is the steady-state load.
02
Sum starting watts
Compressor loads × 3 (single-speed surge). LED lights have no surge. Well pump and AC use 3× surge.
03
Add 20% safety margin
Required generator size = starting watts × 1.2. Round up to next standard portable or standby tier.
04
Pick a generator class
<3,000W: portable inverter. 3,500–5,000: standard portable. 5,000–7,500: tri-fuel portable. 7,500+: standby recommended.

Questions

Frequently asked

A typical full-size fridge runs at 100–800 watts but surges to 1,200–2,400 watts at startup. A 2,000–3,000W portable generator is the practical minimum for fridge-only backup.