Basement Sump Pump Size Calculator – Find Required GPM For Flood Protection

Buying an undersized sump pump leads to flooded basements during heavy rainstorms. This sizing calculator estimates the minimum gallons per minute (GPM capacity) you need, factoring basement square footage and vertical discharge lift head for residential basement and crawl space water removal systems.

Tool Features

• Calculate minimum required sump pump GPM output
• Adjust capacity for vertical discharge lift height loss
• Three regional rain intensity zone presets
• Sizing guide for full basements and low crawl spaces
• Free home waterproofing planning tool for homeowners

Common Usage Scenarios

• Old basement waterproofing pump replacement planning
• New home construction sump system sizing
• Flood-prone crawl space pump selection
• Comparing submersible pump horsepower ratings

Frequently Asked Questions

Q: How does vertical lift reduce pump performance?

A: Each foot of vertical discharge reduces pump flow rate, so deeper basements need higher base GPM ratings.

Q: What size pump do most average basements use?

A: Standard 1/3 HP pumps deliver ~60 GPM for small basements; 1/2 HP handles larger heavy rainfall homes.