Sump Pump Runtime Calculator
Estimate sump-pump runtime and electricity cost from inflow volume, pump flow, cycle size, motor power and operating days.
Default project preview
34.3 minutes/day
Runtime per cycle
21 sec
Daily cycles
100
Monthly runtime
17.1 h
Monthly energy
6.39 kWh
Calculator
Build the material order
Your order will appear here
Enter the project details and calculate a rounded material estimate.
Input and output guide
What each value means
The labels and units below are part of this calculator’s visible methodology. Replace every default with measurements or product data from the actual project.
Average water entering sump
Enter this project assumption in gal/day. The current imperial default is 1200 gal/day.
Delivered pump flow
Enter this project assumption in gpm. The current imperial default is 35 gpm.
Water removed per pump cycle
Enter this project assumption in gal. The current imperial default is 12 gal.
Motor input power
Enter this project assumption in hp. The current imperial default is 0.5 hp.
Operating days per month
Enter this project assumption in a unitless value. The current imperial default is 30. Minimum: 0. Maximum: 31.
Electricity rate
Enter this project assumption in per kWh. The current imperial default is 0.18 per kWh. Minimum: 0.
How to read the outputs
Runtime per cycle
cycle volume ÷ delivered flow. Default preview: 21 sec.
Daily cycles
daily inflow ÷ cycle volume. Default preview: 100.
Monthly runtime
30 operating days. Default preview: 17.1 h.
Monthly energy
0.37 kW input. Default preview: 6.39 kWh.
Monthly energy cost
pump motor only. Default preview: $1.15.
Annualized energy cost
twelve equal months. Default preview: $13.81.
Methodology
Transparent calculation
BuildMeter converts every input to a consistent internal unit, applies the selected allowance, and rounds products up to whole purchasable units.
Daily runtime = daily inflow ÷ delivered pump flow. Cycles = inflow ÷ water removed per cycle. Energy = motor input × monthly runtime.
Reviewed project guidance
How to use this estimate in a real project
Last reviewed: July 30, 2026
Use the Sump Pump Runtime Calculator to estimate a planning quantity from verified pit inflow, pump capacity and usable pit volume. It supports scope comparison, purchasing and operating-cost planning, but it does not select equipment, approve code compliance or replace project-specific design.
Calculation steps
- 1Measure or obtain each design input from the actual project and keep one consistent unit system.
- 2Enter pit inflow, pump capacity and usable pit volume using product data or approved design information rather than generic nominal values.
- 3Review the unrounded engineering or usage result before applying allowances, duty cycle, efficiency or tariff assumptions.
- 4Apply each adjustment once, then round only the final purchasing, equipment-count or scheduling output.
Worked numerical example
With 30 gallons of usable pit volume and net inflow of 10 gpm after pumping begins, a 40 gpm pump removes the stored volume at a net 30 gpm, or about 1 minute in the simplified case.
Purchasing and rounding
Use pump capacity at the actual discharge head, not the zero-head catalog maximum. Confirm pit volume, switch levels and discharge restrictions when evaluating cycle time.
Interpret the result
The simplified runtime follows usable pit volume and net pumping rate. Real cycles change as inflow varies and pump capacity changes with head; short cycling can indicate a control or sizing issue.
Page-specific assumptions
- Inputs describe the actual connected system or measured project scope.
- One operating condition, product rating and unit system are used per calculation.
- Allowances and efficiency losses are not already embedded in the entered values.
- Code, health, structural, electrical and hydraulic requirements are verified independently.
Common mistakes
- Using nominal equipment ratings instead of delivered performance at design conditions.
- Mixing instantaneous flow or power with daily or annual energy.
- Applying the same allowance more than once.
- Treating a quantity or cost estimate as equipment selection or professional approval.
Primary and technical references
BuildMeter provides planning estimates, not engineering, architectural, electrical, mechanical, plumbing, permit or code approval. Review the methodology and verify final decisions with product documentation and qualified professionals.
BuildMeter Guides
Understand the measurements and assumptions
Use these visible reference guides before changing project inputs or planning allowances.
FAQ
Sump Pump Runtime Calculator questions
Why does actual flow differ from the pump label?+
Pump curves show flow at different head. Vertical lift, pipe friction and fittings reduce delivered flow.
Is frequent cycling harmful?+
Very short cycles can increase starts and wear. Pit dimensions and switch settings affect cycle volume.
Does this size a backup system?+
No. Backup sizing must consider outage duration, peak inflow, battery condition and alarm strategy.