This lookup covers 1/2, 3/4 and 1 HP well pumps rated at 240 V. The values are planning typicals from the reviewed BGT 1.2.2 dataset, not specifications for every pump with the same horsepower.
| Pump size | Running power | Starting power | Confidence |
|---|---|---|---|
| 1/2 HP | 875 W (range 670–1,500 W) | 1,750 W (range 1,500–4,500 W) | High |
| 3/4 HP | 940 W (range 940–1,310 W) | 1,880 W (range unknown–unknown W) | Low; startup is estimated, and its range bounds are unknown |
| 1 HP | 1,500 W (range 1,000–2,000 W) | 3,000 W (range 2,000–6,000 W) | High |
Running watts are the power used after the motor is operating. Starting watts are the brief higher demand when the motor starts. Account for both when making a preliminary generator plan, but verify your pump's voltage and model-specific ratings before selecting equipment.
One-pump generator check
For one pump with no other loads, the registered check returns:
| Pump size | One-pump planning requirement |
|---|---|
| 1/2 HP | 1,094 W running, 1,750 W starting |
| 3/4 HP | 1,175 W running, 1,880 W starting |
| 1 HP | 1,875 W running, 3,000 W starting |
The running figure includes this calculation's built-in allowance: it divides the typical running watts by 0.80. The starting figure accounts for one pump start. This method belongs to the registered scenario; it is not a universal generator-sizing rule.
A candidate generator must meet the calculated running requirement with its continuous rating and the starting requirement with its applicable surge rating. The check does not include lights, refrigeration, heating equipment, phone charging or any other household load. It also does not establish that a particular generator is electrically compatible with the pump installation.
How to use these well-pump values
Use the typical value for an early planning estimate when the exact pump information is unavailable. Use the supplied range to see how much pumps with the same nominal horsepower can vary. Horsepower alone does not determine electrical demand; motor design, pump loading, controls and supply conditions can affect the result.
For a preliminary check:
- Match your pump's horsepower and confirm that it operates at 240 V.
- Compare the generator's continuous or running rating with the calculated running requirement.
- Compare its surge or starting rating with the pump's starting requirement.
- Add essential loads that must operate at the same time. Leave optional loads off during a pump start, or schedule them to run separately where practical.
Do not apply these 240 V values to a pump with a different voltage. This lookup does not calculate other pump sizes, multiple pumps or combined household loads.
How to check your actual well pump
Start with installation records and labels you can reach safely. Depending on the system, the information may be on an accessible motor label, an above-ground control box or the installation documentation. Useful entries include:
- Voltage (V)
- Current or amperage (A)
- Horsepower (HP)
- Phase
- Model number
- Locked-rotor current or another starting-current rating
Do not pull or access a buried or submerged pump merely to read its label. If records and accessible controls do not identify it, ask a qualified pump technician or electrician to identify the motor and connection requirements.
Be careful with current-based estimates. Multiplying AC voltage by current gives volt-amperes (VA), an apparent-power value. It does not by itself establish real power in watts because motor power factor and operating conditions matter. Treat a conversion from current to watts as an estimate unless the necessary model-specific factors or measured watts are available.
This verification is especially important for the 3/4 HP entry. Its 1,880 W typical startup figure is a low-confidence estimate based on a 2.0 start-to-run ratio. No lower or upper startup bound is supplied. Matching data for the actual model should replace that estimate when available.
Running watts are not daily energy use
Watts describe power while the pump is operating. Daily energy also depends on how long it runs:
Energy in Wh = power in W × operating time in hours
1,000 Wh = 1 kWh
A running-watt value cannot tell us daily kWh unless we also know the pump's total operating time. This lookup supplies no daily run time, duty cycle or measured energy, so it does not provide Wh/day, kWh/day or generator runtime. Unknown operating time is not zero.
Limits and evidence
These figures support preliminary power planning only. The one-pump result is a demand envelope, not proof that a particular generator can operate a particular installation.
A separate compatibility check must confirm the generator's 240 V output, continuous and surge ratings, receptacle or connection arrangement, and suitability for the pump controls. This calculation does not assess voltage or frequency behavior during startup. An electrician should handle permanent wiring and transfer-switch connections.
The displayed figures come from the page's reviewed BGT 1.2.2 binding. No source excerpts or URLs were supplied for citation here, so this article does not present the underlying external references as independently checked. The 3/4 HP startup value remains estimated, and we do not infer its unknown range bounds from the other pump sizes.
What to check next
First, confirm the pump's voltage, horsepower and model information from accessible records or controls. Then compare both calculated requirements with the generator's corresponding running and starting ratings, and confirm that it supplies the required 240 V output and connection.
If the generator must also power household equipment, list essential loads separately from optional loads. Include essential equipment that must run with the pump, and schedule optional high-power equipment to take turns where practical. Use the broader well-pump sizing page for an outage scenario or the home generator calculator for an editable multi-load plan.