The units behind the answer

Start with what you know.

Choose a conversion or a quantity to solve. Enter each known value with its unit. The tool converts to US gallons and minutes, performs the formula and converts to your requested unit.

Three relationships

• Rate = volume ÷ time.
• Volume = rate × time.
• Time = volume ÷ rate.

Rate is constant or an average over the stated interval. Zero is allowed as a quantity, but a denominator must be greater than zero.

Definitions

All gallons are US liquid gallons. One foot is twelve inches; one cubic foot is 1,728 cubic inches. A US liquid gallon is 231 cubic inches, so a cubic foot is 576/77 US gallons. A day is a fixed 24-hour duration: 1,440 minutes.

MGD means million US gallons per day. One gpm equals 0.00144 MGD. One cfs means one cubic foot per second.

Metric volume units use 1,000 liters per cubic meter and 3.785411784 liters per US liquid gallon. Metric flow options are liters/second and cubic meters/hour. See the metric worked examples and source.

Rounding

The tool uses the unrounded definition-derived factors internally and shows up to ten significant digits. Practice answers are accepted within 0.0005 of the unrounded answer, allowing rounding to three decimal places. Official study sheets may use factors such as 7.48 or 694; do not mix those approximations with this tool's worked answers.

Worked conversion pages

• GPM to MGD
• CFS to GPM
• Liters/second to cubic meters/hour

Primary references

• NIST Handbook 133, Appendix E, 2017: dimensional definitions used for the gallon/cubic-foot relationship.
• California drinking-water conversion sheet: retrieved September12, revised April30,2026; notation, formulas and rounded factors.
• California wastewater equivalents and formulae, January2014: historical educational reference, not a statement of current examination requirements.

Progress and scope

Correct answers add a unique problem to local progress. Revealing an answer alone does not count it as solved. Progress stays in this browser and can be reset. This tool supplies no treatment, dosing, safety, exam-pass or certification advice.