What size inverter for a refrigerator?
A household fridge running at 200 W needs only about 250 W continuous — but up to 1,200 W for a moment to start its compressor. That means at least a 600 W pure sine inverter if its surge rating is twice its continuous rating; check the spec sheet, and a 1,000 W unit gives more margin.
How to work it out
- Running: 200 W × (1 + 25%) = 250 W → 600 W inverter
- Surge: 200 W running + biggest start-up extra = 1,200 W
- Battery current: 200 W ÷ 90% ÷ 12 V = 18.5 A (55.6 A at 600 W)
Fridges are where inverter sizing goes wrong most often: the running watts are small, but the compressor needs a hefty kick to start. Champion’s chart lists 150–400 running and 800–1,200 starting watts for a household refrigerator; this page uses 200 W and the top of the starting range.
Adjust for your project
More options: Headroom · Inverter eff.
- Running watts, all together
- 200 W
- Continuous rating with headroom
- 250 W
- Surge (peak) rating needed
- 1,200 W
- Battery current at your load
- 18.5 A
- Battery current at the inverter’s full rating
- 55.6 A
- Sized up for the start-up surge. 250 W continuous would be enough to run everything, but the start needs 1,200 W. This assumes an inverter whose surge rating is twice its continuous rating — many are rated about that way, but surge ratings and how long they last vary, so check the spec sheet.
- The biggest motor start adds 1,000 W for a moment. Check the inverter’s surge or peak rating on its spec sheet — it must cover 1,200 W, even if the continuous rating is smaller.
- For motors, compressors, CPAP machines and electronics, choose a pure sine wave inverter.
Battery current at other battery voltages
| Battery voltage | Battery current at your load | Battery current at the inverter’s full rating |
|---|---|---|
| 12 V | 18.5 A | 55.6 A |
| 24 V | 9.3 A | 27.8 A |
| 48 V | 4.6 A | 13.9 A |
What to know about a fridge on an inverter
- Read the spec sheet’s surge figure. Inverters list a peak or surge rating, often for a second or two. That figure, not the continuous one, is what starts the compressor.
- Pure sine matters here. A compressor motor on a modified-sine inverter runs hotter and noisier.
- Idle draw adds up. The fridge cycles, but the inverter stays on 24 hours, so its no-load draw counts all day. An efficient inverter in the right size range helps.
- A 12 V compressor fridge avoids all of this. No inverter, no surge, no idle draw — see how long a 100Ah battery runs a fridge.
The energy side — battery and panels — is on how many watts a refrigerator uses per day and how many solar panels to run a refrigerator. With a generator instead, see what size generator to run a refrigerator.
Different size? Use the full Inverter Size Calculator.
What you’ll need
- Pure sine wave inverter, 1000 WMid-range price
Enough for a CPAP, laptop, TV and small appliances. Pure sine is the safe choice for anything with a motor or sensitive electronics.
See options on Amazon (opens in a new tab) - 12 V compressor fridgePremium price
A compressor fridge runs straight off the battery with no inverter loss — usually the single biggest load in a van or boat system.
See options on Amazon (opens in a new tab) - Plug-in electricity usage monitorBudget price
Plugs in between the wall and a 120 V appliance and shows real watts and kWh over a day — the honest way to fill in a load list, especially for fridges that cycle on and off.
See options on Amazon (opens in a new tab)
As an Amazon Associate we earn from qualifying purchases. Links to products are affiliate links — they cost you nothing extra and help keep these calculators free.
Frequently asked questions
What size inverter for a mini fridge?
About 300 W continuous with a surge rating of at least 600 W (Champion: mini fridges 50–100 running, 400–600 starting watts).
What size inverter for a refrigerator and a freezer?
About 800 W continuous; surge at least 1,350 W if only one compressor starts at a time.
Other common sizes
- What size inverter to run a microwave — 1,500 W pure sine (for a 1,200 W microwave)
- What size inverter to run a CPAP — 150 W pure sine (300 W with a heated humidifier)
- How many amps a 1000 watt inverter draws — 92.6 A
- How many amps a 2000 watt inverter draws — 185.2 A
Sources
- Champion Power Equipment — Generator Wattage Chart (opens in a new tab) — Typical running and starting watts for household, RV and job-site appliances (a manufacturer’s planning chart — your nameplate wins).
- Virginia Cooperative Extension, BSE-301: Estimating Appliance and Home Electronic Energy Use (2020) (opens in a new tab) — Wattage × hours ÷ 1,000 = kWh per day; watts = amps × volts when only amps are listed; a refrigerator runs at full wattage about a third of the time; typical nameplate wattages.
- Victron Energy — Energy Unlimited (book) (opens in a new tab) — Lead-acid charge efficiency 80–95% (85% suggested as a starting value); battery energy efficiency about 75% for full cycles, about 89% in partial state of charge; inverter efficiencies above 90%.
- Victron Energy — Lithium Battery Smart manual, technical data (opens in a new tab) — LiFePO4 12.8 V: cycle life 2,500 at 80% DoD, 3,000 at 70%, 5,000 at 50% (to 80% of capacity); 92% round-trip efficiency; 12.8 V 100 Ah: recommended continuous discharge ≤100 A (1C), maximum 200 A; capacity about 20% lower at 0 °C; charge only between +5 °C and +50 °C.
- ENERGY STAR — Certified Televisions data set (on-mode power) (opens in a new tab) — Certified models, on-mode watts, retrieved October 2026: 32 in about 27–36 W; 43 in about 45–78 W; 50 in about 61–90 W; 55 in about 64–114 W; 65 in about 85–135 W; 75 in about 120–176 W.