How Many Watt-Hours to Run a Fridge for 24 Hours?
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This guide helps you size a portable power station for refrigerator backup using public energy labels and simple math. It is not a hands-on lab test of any fridge or battery brand.
Jump to: formula · worked examples · station class matching · sources
Related guides: DELTA 3 vs 1000 v2 vs Elite 100 V2 · EcoFlow vs Anker SOLIX home backup · solar recharge math · Watt-Hour Calculator page
The short answer
Use your fridge’s EnergyGuide / ENERGY STAR annual kWh, then:
Wh per day ≈ (kWh/year × 1000) / 365
Examples using ENERGY STAR category medians (Fridge.com analysis of ENERGY STAR certified models, data through Feb 2026; cite Fridge.com Energy Index summarizing DOE ENERGY STAR data):
| Fridge type (ENERGY STAR certified set) | Median kWh/year | ≈ Wh/day |
|---|---|---|
| Top freezer | 362 | ≈ 991 Wh/day |
| Bottom freezer | 553 | ≈ 1,515 Wh/day |
| Side-by-side | 644 | ≈ 1,764 Wh/day |
| Compact refrigerator | 246 | ≈ 674 Wh/day |
So a modern top-freezer often needs on the order of ~1 kWh of battery energy per day of fridge-only load — before inverter losses, door openings, hot kitchens, or other devices.
Always prefer your model’s EnergyGuide label over category medians.
Running watts vs daily energy
Fridges cycle. Nameplate or “running watts” (often ~100–200 W for many full-size units when the compressor is on) is not the same as average continuous draw. EnergySage summarizes typical fridge draws in the hundreds of watts when running and notes cycling; see EnergySage: How many watts does a refrigerator use?.
For backup sizing, daily Wh from the EnergyGuide is usually more trustworthy than guessing duty cycle.
Optional cross-check if you only know running watts
If you lack an EnergyGuide number and only know running watts R and assume duty cycle D (often 0.3–0.5 — guessy):
Wh/day ≈ R × 24 × D
Example: R=150 W, D=0.35 → 150×24×0.35 = 1,260 Wh/day. Treat as a rough band only; labels beat guesses.
Surge / startup load
Compressor start can briefly demand multiple times running watts. Your power station needs:
- Enough Wh for the outage length you care about, and
- Enough surge / rated AC watts to start the compressor.
If the station trips when the fridge kicks on, capacity alone will not save you. Compare station surge figures on manufacturer pages (e.g. DELTA 3 3,600 W surge; Explorer 1000 v2 3,000 W surge; Elite 100 V2 high surge/lifting claims — confirm on page).
Worked examples by outage length
Assume top-freezer median ≈ 991 Wh/day, plus a 15 W router (360 Wh/day), margin 1.30:
| Outage length | Fridge Wh | Router Wh | Subtotal | ×1.30 margin | Recommended band |
|---|---|---|---|---|---|
| 8 hours | ≈330 | 120 | 450 | 585 Wh | ~700 Wh+ station |
| 12 hours | ≈495 | 180 | 675 | 878 Wh | ~1 kWh class |
| 24 hours | ≈991 | 360 | 1,351 | 1,756 Wh | expandable / 2 kWh class |
| 48 hours | ≈1,982 | 720 | 2,702 | 3,513 Wh | multi-battery ecosystem |
Bottom-freezer median (~1,515 Wh/day) pushes the 24 h band near ~2.4 kWh after router+margin — plan expansion early (EcoFlow vs Anker expandability).
Matching Wh bands to station classes
| Recommended Wh | Example class (official capacities) | Notes |
|---|---|---|
| < 400 | Explorer 300 v2 288 Wh / Anker C300 288 Wh | Lights/router — not full-size fridge days |
| 400–700 | RIVER 2 Max 512 Wh | Short outages / compact fridge |
| 700–1,200 | DELTA 3 1,024 / 1000 v2 1,070 / Elite 100 V2 1,024 / C1000 1,056 | Common apartment starters |
| 1,200–2,200 | C1000+BP1000 2,112 Wh | One expansion battery |
| 2,200+ | DELTA 3 path toward 5 kWh | Multi-day fridge goals |
Budget shopping tips: under $500 roundup. Chemistry: LiFePO4 vs NMC.
Sizing checklist
- Photograph your EnergyGuide kWh/year.
- Convert to Wh/day.
- Add other loads (router, lights, medical devices — check labels; for CPAP travel see CPAP travel guide).
- Apply 20–40% margin.
- Verify surge on the station datasheet.
- If outages last days, plan solar input (charge-time math).
Use the Watt-Hour Calculator
Plug device watts × hours into our Watt-Hour Calculator lead magnet for a recommended Wh band.
Sources
- ENERGY STAR Refrigerators
- Fridge.com Refrigerator Energy-Efficiency Index
- EnergySage fridge wattage overview
Last reviewed: 2026-09-24 (MDT).