Cannabis Runoff Percentage Calculator

Calculate irrigation runoff

Measure the total solution applied to a container or irrigation zone and the runoff collected after drainage. The calculator divides collected runoff by applied volume and reports the result as a percentage.

Applying 2 liters and collecting 0.3 liters produces 15% runoff. The remaining 1.7 liters is described as retained, although some may remain in trays, tubing, or unmeasured drainage.

Measure consistently

Allow drainage to finish for the same amount of time during each test. Use a clean tray or collection vessel and measure several representative containers. In multi-emitter systems, verify delivered volume as well as runoff because clogged or mismatched emitters can hide distribution problems.

Runoff is a diagnostic signal

Runoff percentage can help describe irrigation behavior, but it should not be used alone. Substrate type, container size, root density, irrigation frequency, salinity strategy, and environmental demand all affect an appropriate approach. Some cultivation systems intentionally use little runoff, while others use controlled drainage.

Useful records

• Record input and runoff EC or PPM separately.
• Note the time between irrigation and measurement.
• Track several containers rather than only the easiest one.
• Watch dryback and plant response alongside runoff.

This calculator provides a measurement, not a universal runoff target. Adjust irrigation using root-zone data and crop response.