Calculator
Well Pump Size Calculator
Size a well pump from depth, flow demand and total dynamic head.
Verified August 2026
Recommended pump
2 HP
10 GPM at 351 ft of head
- Total dynamic head
- 351 ft
- Pressure head
- 116 ft
- Friction loss
- 11 ft
- Calculated water horsepower
- 1.61
Estimates only. Local pricing, site conditions and code requirements change the real number.
The formula
Total dynamic head = pumping depth + elevation lift + pressure head + friction loss
Pressure head converts at 2.31 feet per psi, so a 50 psi system adds about 115 feet of head before you count depth or friction.
Worked example
A 200 ft well delivering 10 GPM to a fixture 25 ft above grade at 50 psi needs roughly 360 ft of head — a 1 HP pump.
Frequently asked questions
What size well pump do I need?
Most single-family homes on wells under 250 feet use a 1/2 to 1 HP submersible pump delivering 8 to 12 GPM. Deeper wells and higher pressure demands push you to 1.5 HP and up.
How many GPM does a house need?
Plan on about 1 GPM per fixture likely to run at once — 8 to 12 GPM covers most three-bedroom homes.
Sources
Sources & verification
Last verified August 2026. Cost figures are modeled estimates based on national baselines adjusted for local labor and material pricing — they are not quotes. Permit rules change; confirm with the building department before starting work.