Measure sump basin working volume and discharge pipe
A sump pump installation involves a basin, pump, discharge assembly, electrical supply and sometimes a backup system. The basin stores water between activation and stop levels, but that storage volume alone does not tell you how powerful a pump needs to be. Inflow rate, lift height and pipe friction influence pump selection. This calculator measures the working volume inside a cylindrical basin and separately counts complete discharge-pipe lengths for budgeting.
Enter the basin's inside diameter rather than the outside dimension printed on a product listing. The working water height is the vertical difference between the selected start and stop water levels, not necessarily the entire basin depth. For discharge piping, follow the measured route specified by the installer, including changes of direction and the point where drainage is permitted to terminate.
Working volume and discharge quantities
Working water (US gal) = cubic feet × 7.48052
Pipe required = discharge run × (1 + cut allowance ÷ 100)
Complete stock pieces = round up (required pipe ÷ stock length)
Actual pump cycling depends on how the control float operates, the effective basin shape and the rate at which groundwater enters. The calculated gallons are a geometric volume, not a tested pump capacity. A manufacturer-rated pump curve, total dynamic head and a site-specific discharge design are needed for equipment selection. The stock count also excludes the specialty elbows and adapters that may be included in a separate installer quotation.
Worked example: an 18-inch basin
An inside diameter of 18 inches is 1.5 feet, giving a radius of 0.75 feet. If the float settings create a 10-inch working depth, volume is π × 0.75² × (10 ÷ 12) = approximately 1.473 cubic feet, or about 11.02 US gallons. A 32-foot discharge route with 10% cut allowance requires 35.2 feet of pipe. At 10 feet per stock piece, the order rounds up to four pieces.
If the four pipe pieces are quoted at $12 each and a specified check valve costs $35, those two materials total $83. The pump, basin, electrician, labor and any battery backup remain separate because these amounts cannot be inferred from basin dimensions.
Installation scope that affects a sump pump quotation
Replacing a failed pump inside a sound existing basin is different from cutting a new sump pit into a basement floor. A new installation may require concrete cutting, excavation, gravel, a sealed lid, plumbing through a foundation wall, an appropriate discharge location and an electrical receptacle. Where backups are specified, distinguish battery, secondary pump and monitoring equipment from the primary pump quote.
Use the separate fields for equipment, basin, valve assembly, pipe, labor, electrical work and other contractor-priced items. If the chosen pump package includes a valve or basin lid, do not enter it again. Check local discharge requirements; draining to an unsuitable location can move water back toward the foundation or violate municipal rules.
Sump pump estimation questions
Does the basin gallon result tell me which horsepower pump to buy?
No. Horsepower alone does not describe the delivered flow against total dynamic head. Water inflow, vertical lift, discharge length and fitting losses must be evaluated using the pump manufacturer's curve and a qualified installation assessment.
Why does the calculator show whole pipe pieces?
Retail stock lengths are purchased as complete units. A required run of 35.2 feet needs four 10-foot pieces, although fittings, cutoffs and possible stock alternatives may change the final order. Check pipe diameter and material against the pump's specified discharge connection.
Is a battery backup included in the budget automatically?
No. Backup configurations differ in pump design, controls, battery capacity and monitoring options. Enter the actual supplied price in the electrical and backup field only when it belongs to the work being quoted.