Free point-source drip calculator

How much water do entered drip emitters represent?

Enter the actual emitter count, each emitter's stated or measured rate, and runtime. TerraEvidence calculates total point-source flow and water volume without assuming every emitter delivers that rate in the installed system.

Calculate drip output See the exact method

Start hereChoose units

U.S.U.S. gallons per hour and U.S. gallonsMetricLitres per hour and litres

Required evidence labelWhere did the emitter rate come from?

MeasuredOutput physically measured by the userManufacturer-ratedCopied rating; not a measurementUnknown sourceUser-entered rate with unspecified basis

Actual emitter countemittersCount the point emitters; do not infer endpoints from line length and spacing. Entered rate per emitterU.S. gal/hUse one common rate for this emitter group. Separate unlike emitter rates into separate calculations. RuntimeRuntime is an arithmetic input; this tool does not set a watering schedule. Optional entered source flowU.S. gal/hCompare an independently measured or otherwise entered source-flow capacity. Leave blank to skip.

Transparent method

Emitter count multiplied by rate and runtime

The first release asks for the actual point-emitter count instead of estimating count from tubing length and spacing. Use separate calculations for groups with different entered emitter rates.

When source flow is entered, TerraEvidence subtracts the calculated emitter total from that entered capacity. The comparison flags arithmetic only; it does not model pressure or diagnose the system.

Total-flow formulatotal flow = emitter count × entered rate per emitterRuntime-volume formulawater volume = total flow × runtime hoursOptional capacity formuladifference = entered source flow − calculated emitter total

Example: 20 emitters × 1 U.S. gal/h × 0.5 h represents 10 U.S. gallons. Actual installed output must be measured if actual delivery is needed.

Related Water Tools

Continue with the measurement you need.

Use one tool or follow the full pathway. These tools calculate from entered or measured values; they do not decide whether or how much to water.

1Measure source flow
Bucket-test a faucet, hose, or installed setup.
2Calculate drip output
Multiply entered emitter count, rate, and runtime.
Current tool
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4Convert rain to volume
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