What Size Generator Runs a Well Pump? (HP + 240V Chart)

Wattage data last verified 2026-08-28 · every wattage cites its source · methodology

A well pump alone needs 1,000 running watts and 2,100W available at startup — with 20% headroom, look for a generator rated around 2,600W. Running the full kit below at the same time takes 3,280 running watts (5,000W peak) → ~6,000W rated.

The list, with sourced watts

ApplianceRunning wattsStarting (surge)
Well pump (1/2 HP)1,0002,100
Well pump (3/4 HP, 240V submersible)1,6003,400
Well pump (1 HP, 240V submersible)2,0004,000
Well pump (1.5 HP, 240V submersible)2,2804,000
Refrigerator/freezer (standard household)1,0002,200
Running watts versus starting surge, per appliance Horizontal bars for 5 appliances. The solid bar is running watts; the lighter extension is the extra the motor briefly demands at startup. Well pump 1,000 running, 2,100 starting. Well pump 1,600 running, 3,400 starting. Well pump 2,000 running, 4,000 starting. Well pump 2,280 running, 4,000 starting. Refrigerator/freezer 1,000 running, 2,200 starting. running watts extra at startup Well pump 1,000 → 2,100W Well pump 1,600 → 3,400W Well pump 2,000 → 4,000W Well pump 2,280 → 4,000W Refrigerator/freezer 1,000 → 2,200W
The startup surge is the part a generator has to cover but a spec sheet rarely leads with — here the well pump (1 HP, 240V submersible) briefly demands 2,000W more than it runs on. Same figures as the table, each cited on the methodology page.

The arithmetic, both ways

Well pump (1/2 HP) alone: 1,000W running + 1,100W surge = 2,100W → × 1.2 = ~2,600W

Full kit (every item below, at once): 3,280W running + 1,720W largest surge = 5,000W → × 1.2 = ~6,000W

Generators for the well pump alone

No unit in our verified catalog cleanly covers this load — see the calculator to adjust your list.

Covering the full kit (~6,000W)

Generac GP6500 COsense (76803)
6,500W rated · 8,125W starting · gasoline
Spec: manufacturer

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Champion 201175 (8500W Electric Start Dual Fuel Inverter)
7,000W rated · 8,500W starting · dual fuel (gasoline/propane) · inverter
Spec: manufacturer

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Data note: All three 240V tiers require a generator with a 240V outlet (L14-30 class) — page must gate recommendations on 240V capability.
Data note: well_pump_15hp starting surge (4,000 W additional) is a FLOOR per Erayak '6,000W+ possible'; Franklin AIM Table 3 minimum-generator classes (3/4HP:3kW, 1HP:4kW, 1.5HP:5kW; +50% for 2-wire motors) are the governing recommendation floor.

Adjust this list in the calculator →

How many watts do I need for a well pump?

1,000 running watts with 2,100W available at startup; ~2,600W rated recommended. The full kit on this page needs ~6,000W.

Why do starting watts matter?

Motor-driven appliances (fridges, pumps, AC compressors) briefly draw 2–4× their running watts at startup. A generator must cover running load plus the largest single surge, or the motor stalls and breakers trip.

Is a bigger generator always better?

No — oversized open-frame units burn more fuel and run louder. Size to your real list with ~20% headroom.

Sources

Figures are conservative sizing values chosen from the range these sources report. Your appliance's nameplate is authoritative.