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

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

Appliance	Running watts	Starting (surge)
Well pump (1/2 HP)	1,000	2,100
Well pump (3/4 HP, 240V submersible)	1,600	3,400
Well pump (1 HP, 240V submersible)	2,000	4,000
Well pump (1.5 HP, 240V submersible)	2,280	4,000
Refrigerator/freezer (standard household)	1,000	2,200

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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See Champion 201175 (8500W Electric Start Dual Fuel Inverter) on Amazon →

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.