Well Pump Sizing Calculator

Total dynamic head, horsepower class, and pressure tank size from well depth, fixture lift, flow rate, pipe friction, and system pressure

Size a residential well pump from the pumping (or static) water level, additional lift to the highest fixture, desired GPM (manual or bathroom-count estimate), pipe diameter and length for friction loss, and cut-in/cut-out PSI. The calculator reports TDH in feet, a typical 1/2 / 3/4 / 1 / 1.5 HP band that covers that GPM at that head, and a pressure-tank size for about one minute of drawdown between cycles. Starting point only — not a manufacturer pump curve and not a substitute for a well contractor confirming yield, wire, and local code.

How TDH becomes HP: sizing guide. Short-cycling and no pressure: troubleshooting. Submersible vs jet: comparison. Quick depth table: sizing chart. Plumbing index: plumbing calculators hub.

A basement sump is a different pump: sump pump sizing calculator. Supply pipe after the tank: water supply pipe sizing. Rural waste side: septic tank sizing.

Starting point only — not a named-model pump curve. TDH = vertical lift (well depth + fixture lift) + Hazen-Williams friction (PVC C=150) + pressure head (cut-out PSI × 2.31). Horsepower bands interpolate typical residential submersible catalog-order capacities at 50–400 ft TDH for 1/2, 3/4, 1, and 1.5 HP. Tank gallons assume about one minute of pump run time and a bladder-tank drawdown factor (~0.28 for 40/60). Confirm the published GPM at your actual TDH, pre-charge the tank 2 PSI below cut-in, and verify well yield before you buy.

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How to Use This Well Pump Sizing Calculator

Enter the pumping (or static) water level, the rise from grade to the highest fixture, the GPM you need (or a bathroom-count estimate), drop/supply pipe diameter and developed length, and the pressure-switch cut-in/cut-out. The tool adds vertical lift, Hazen-Williams friction (C=150 PVC), and pressure head (cut-out PSI × 2.31) into total dynamic head, then picks the smallest typical 1/2–1.5 HP residential band that still makes that GPM at that TDH and sizes a bladder tank for roughly one minute of drawdown.

TDH = (well depth + fixture lift) + friction head + (cut-out PSI × 2.31)

Why those three terms matter: sizing guide. Short-cycling and waterlogged tanks: troubleshooting. Submersible vs jet is depth architecture, not the GPM formula: comparison. Ballpark before you measure pipe: sizing chart.

What This Number Is (and Is Not)

A well pump is sized at a point on a curve: gallons per minute at total dynamic head. Horsepower on the carton is shorthand. A 1 HP pump at 150 ft TDH and the same pump at 320 ft TDH are not the same machine. This tool makes you enter depth, friction, and pressure on purpose.

Well pump ≠ sump pump. A sump moves groundwater out of a basement crock. A well pump delivers potable supply under continuous pressure. Different worksheet: sump pump sizing calculator.

Already short-cycling on a “big enough” pump? Waterlogged tank and a failed check valve fake an undersize.

Troubleshooting →

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Well Pump Install Gear

TDH and HP pick the pump. Torque arrestors, well-rated cable, and a pressure switch calibrated to the tank you actually have are why a “right-size” pump still cycles every 15 seconds or can't reach the second floor.

Submersible Well Pump (1/2 HP Class)

Typical shallow-to-moderate depth residential. Confirm the curve at your total dynamic head, not the HP alone.

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Convertible Jet Pump

Shallow or deep configuration depending on static lift. Above-ground service. Check if your depth is in jet or submersible territory.

View on Amazon →

Amtrol Well-X-Trol 20 Gal Pressure Tank

Adequate drawdown for typical household demand. Prevents short-cycling when matched to the pressure switch range.

View on Amazon →

Square D Pumptrol 40/60 Pressure Switch

Standard residential band. Cut-in at 40 PSI, cut-out at 60. Must match your tank drawdown capacity and plumbing fixture minimums.

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Torque Arrestor

Prevents submersible pump from spinning on start-stop. Unanchored motors twist the drop pipe and stress wiring.

View on Amazon →

Well Pump Cable

Submersible-rated, UV-resistant jacket. Must handle depth, voltage drop, and wet environments. Size by depth and pump load.

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Well Pump Sizing Calculator

How to Use This Well Pump Sizing Calculator

What This Number Is (and Is Not)