Free Tool

Well Pump Sizing Calculator

Estimate the submersible pump flow rate, horsepower, and total head your home needs from your well depth and household demand — and if your pump short-cycles, size the pressure tank that fixes it.

Your Well

Tell us about your setup

Pump setting depth How deep the pump sits in the well, in feet. If you only know the well depth, use that.

200 ft

Number of bathrooms Bathrooms are the standard way to estimate a home's peak water demand.

Household size (optional cross-check) A rough sanity check against bathroom count — bathrooms still drive the recommendation.

Peak fixtures running at once (optional) If you know how many showers, taps, or appliances run together at your busiest moment.

Your Estimate

Recommended pump

10 GPM

Flow rate

¾–1 HP

Motor size

Estimated peak demand 12 GPM

Total dynamic head ~240 ft

Well-depth band Standard depth

Estimate only. This is a 2025–2026 rule-of-thumb sizing guide. Your pump can't deliver more than the well's own yield — a licensed driller or pump installer should confirm the size against a flow test before you buy.

Why a pro has to confirm this

A pump can only deliver what your aquifer produces. If your well's sustained yield is, say, 5 gallons per minute, a 12 GPM pump will draw it down and short-cycle — the surest way to burn out a motor early. A licensed driller runs a flow test on your actual well and matches the pump to its real yield, your depth, and your pressure needs. Use this estimate to walk into that conversation informed, not to place an order.

The Math

How this estimate works

Peak demand from bathrooms

A common residential rule of thumb: start at 6 GPM for one bathroom, add about 3 GPM per extra bathroom, capped near 17 GPM. We then round up to the next standard pump size.

Total head from depth

Total dynamic head is roughly your pump setting depth plus about 40 feet to cover household pressure and pipe friction. Deeper wells need a pump that can push water higher.

Horsepower from depth + flow

Shallow, low-flow wells often run on ½ HP; mid-depth homes on ¾–1 HP; and deep or high-flow wells on 1½–2 HP. We pick the band your numbers land in.

Pump clicking on and off?

Pressure-tank & short-cycling check

If your pump snaps on and off every few seconds, it's short-cycling — the fastest way to burn out a pump. Almost always the pressure tank is too small or has lost its air charge. Here's the tank size that stops it.

Your Pump

Size the pressure tank

Pump flow rate (GPM) Off the pump label, or use the flow rate from the calculator above.

10 GPM

Pressure switch setting The cut-in / cut-out pressure, marked on the switch under the cover.

Minimum run-time per cycle Industry minimum is 1 minute; 2 minutes is gentler and makes a pump last longer.

Your current tank (optional) Add it and we'll tell you whether it's the cause.

Recommended tank size

~44 gal

Drawdown your pump needs~10 gal

Usable drawdown of that tank~12 gal

Set the tank's air precharge about 2 psi below your cut-in pressure (with the tank drained) and you'll get the full drawdown above.

Next steps

Before you act on this number.

Jet pump or submersible? Which suits your depth and layout.
Check your well can supply it A bigger pump cannot create water that is not there.
Pump service and replacement What replacement usually involves.

Common questions

Reading this properly.

No, and oversizing causes real problems. A pump that outruns the well draws it down, sucks air, and short-cycles — which wears the motor, the pressure switch and the tank far faster than steady running. Size to the household’s peak demand and the well’s actual yield, not to a round number.

Flow is how much water arrives per minute; pressure is how hard it arrives. A pump has to deliver both, against the vertical lift from the water level to the fixtures plus friction in the pipe. Sizing on flow alone gives you a pump that runs but never quite feels right upstairs.

Peak. Average daily use tells you almost nothing about whether two showers and a washing machine at once will work. Size for the worst realistic simultaneous demand.

Get your pump sized by a licensed pro

A driller's flow test is the only way to match a pump to your well's real yield. Compare listed well drillers and pump installers in your area — direct contact, no referral fees.

Find a licensed well driller →