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Calcimator

Sump Pump Sizing Calculator

Size sump pumps based on pit dimensions, water inflow rate, discharge height, and calculate battery backup duration.

Inputs

inches
inches
GPM
ft
ft

Results

Required Pump Capacity

15 GPM

Recommended Pump HP

0.33 HP

≈ 4 laptops

Total Dynamic Head8.23 ft
Cycles per Hour37.8
Battery Backup Duration2.9 hours
How to Use This Calculator
  1. Enter the sump pit diameter and depth in inches to determine the working volume.
  2. Enter the water inflow rate in GPM — measure during a heavy rain event or estimate from drainage area.
  3. Set the discharge height in feet from the pump to the outlet point.
  4. Enter the total discharge pipe length including horizontal runs.
  5. Review Required Pump Capacity (GPM), Total Dynamic Head (ft), and Recommended Pump HP to select your pump.
  6. Note Battery Backup Hours to size a backup system for power outage protection.

How the result changes with Water Inflow Rate

Water Inflow RateRequired Pump CapacityRecommended Pump HP
1015 GPM0.33 HP
3552.5 GPM0.33 HP
6597.5 GPM0.5 HP
90135 GPM0.75 HP

What each input means

Pit Diameter
Inside diameter of the sump pit or basin in inches.
Pit Depth
Depth of the sump pit from floor level to bottom.
Water Inflow Rate
Rate of water entering the pit. Measure by timing pit fill during heavy rain.
Discharge Height
Vertical distance from pit bottom to the highest point of the discharge pipe.
Discharge Pipe Length
Total length of discharge piping including horizontal runs.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Pit Diameter = 18, Pit Depth = 24, Water Inflow Rate = 10, Discharge Height = 8 = 5 input(s) provided
  2. Calculate Required Pump Capacity
    Required Pump Capacity
    15 = 15
  3. Calculate Recommended Pump HP
    0.33 = 0.33
  4. Calculate Total Dynamic Head
    Total Dynamic Head
    8.23 = 8.23
  5. Calculate Cycles per Hour
    Cycles per Hour
    37.8 = 37.8

Engine last updated . Checked against 1 independently-derived test — how we verify calculators.

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