Well Pump Size Calculator
Calculate the GPM (gallons per minute) and horsepower needed for your well pump. Determine Total Dynamic Head (TDH) based on well depth, water level, and pressure requirements.
Quick Guide: Most homes need 6-12 GPM and 1/2 to 1.5 HP pump
TDH = Pumping Level + Vertical Lift + Pressure (PSI × 2.31) + Friction Loss
🚰 Water Fixtures
💡 Tip: Most homes rarely use more than 30-40% of total potential GPM at once.
📊 Recommended GPM
Recommended Pump Flow Rate
6 - 8 GPM
Target: 6 GPM
💪 Suggested Pump Size:
1/2 to 3/4 HP for typical residential use
💧 How to Size a Well Pump
Choosing the right well pump size ensures adequate water pressure, efficient operation, and long pump life. An undersized pump won't meet your water needs, while an oversized pump wastes energy and may short-cycle.
Step 1: Determine Your GPM Needs
Calculate how many gallons per minute (GPM) your household needs based on water fixtures. A typical home needs 6-12 GPM. Count your fixtures and estimate simultaneous usage (usually 30-40% of total).
Step 2: Calculate Total Dynamic Head (TDH)
TDH Formula:
TDH = Pumping Level + Vertical Lift + (PSI × 2.31) + Friction Loss
- Pumping Level: Depth to water when pump is running
- Vertical Lift: Height from well to highest outlet
- Pressure Head: Desired PSI × 2.31 feet per PSI
- Friction Loss: Typically 5-15% (varies by pipe size/length)
Step 3: Match Pump to TDH and GPM
Select a pump that delivers your required GPM at your calculated TDH. Check the manufacturer's pump curve to verify performance. The pump should operate in its "sweet spot" - not at the extreme ends of its curve.
Important Considerations
- Well Recovery Rate: Your pump shouldn't exceed your well's ability to refill
- Pump Setting Depth: Install pump 20-30 ft below pumping level
- Wire Sizing: Proper wire gauge prevents voltage drop
- Pressure Tank: Size tank to minimize pump cycling (1-2 gal per GPM)
📋 Quick Reference
• Typical home: 6-12 GPM
• 1 PSI = 2.31 ft of head
• 40-60 PSI = 92-139 ft head
• Standard pressure: 40/60 PSI
• Submersible: wells >25 ft
⚡ Pressure Settings
30/50 PSI: Low pressure
40/60 PSI: Standard (most common)
50/70 PSI: High pressure
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Frequently Asked Questions
To size a well pump, you need three key values: 1) Required GPM (gallons per minute) based on your water fixtures, 2) Total Dynamic Head (TDH) which includes pumping depth, elevation, pressure requirements, and friction loss, 3) Match these to a pump's performance curve. A properly sized pump should deliver your required GPM at your calculated TDH without running continuously.
For a 200 ft well pumping to a standard 40-60 PSI pressure tank, you'll typically need a 3/4 HP to 1 HP pump for residential use (8-15 GPM). The exact size depends on your static water level, required pressure, and pipe friction losses. Calculate your Total Dynamic Head (TDH) first, then match it to pump specifications.
Most residential homes need 6-12 GPM. Calculate your needs by counting fixtures: each bathroom adds 2-3 GPM, kitchen sink 1.5 GPM, washing machine 2 GPM, and outdoor faucets 3-5 GPM. Consider how many fixtures might run simultaneously during peak usage (usually 2-3) rather than adding all fixtures together.
Total Dynamic Head (TDH) is the total equivalent height the pump must lift water, measured in feet. It includes: 1) Pumping level (depth to water when pumping), 2) Vertical lift to highest outlet, 3) Pressure requirement (1 PSI = 2.31 ft), 4) Friction loss from pipes (typically 5-15% of total). TDH determines the pump horsepower needed.
Submersible pumps are installed inside the well and are best for wells deeper than 25 feet. They're more efficient, quieter, and longer-lasting. Jet pumps sit above ground and work for shallow wells (under 25 ft for single-pipe, up to 110 ft for two-pipe). Most residential wells over 50 feet deep use submersible pumps.
To test GPM: 1) Let the pump build full pressure, 2) Open a faucet near the pressure tank, 3) Time how long it takes to fill a 5-gallon bucket, 4) Calculate: GPM = (5 gallons ÷ seconds) × 60. For example, if it takes 30 seconds to fill 5 gallons, your flow rate is (5÷30)×60 = 10 GPM.
⚠️ Disclaimer: This calculator provides estimates based on general industry guidelines. Actual pump selection should be verified using manufacturer pump curves and specifications. Well characteristics, local conditions, and specific requirements may vary. Consult a licensed well professional for critical applications.