US gallons per minute to Cubic feet per minute Calculator

Direct answer

Multiply the entered us gallons per minute value by 0.133680555555556 to express it in cubic feet per minute (cfm). This converts US gallon per minute (gpm) to cubic foot per minute (cfm) within the documented flow rate family.

Variables and formula

• US gallons per minute (gpm): the source value measured in US gallon per minute.
• Cubic feet per minute (cfm): the same quantity expressed in cubic foot per minute.
• Conversion factor: 0.133680555555556 cubic feet per minute per US gallon per minute.

Cubic feet per minute = US gallons per minute × 0.133680555555556

The generator emits numeric factors with at most 15 significant digits. Calculator results keep up to 10 significant digits for display; this formatting does not increase the precision of the measurement.

Unit definitions and named variants

Source unit: US gallon per minute (gpm). One U.S. liquid gallon per minute equals exactly 3.785411784 litres per minute because the U.S. gallon is exactly 231 international cubic inches. Named variant used: U.S. liquid gallon only; not Imperial gallon. Reference: National Institute of Standards and Technology: NIST Guide to the SI, Appendix B.9: Factors for Units Listed by Kind of Quantity or Field of Science; National Institute of Standards and Technology: NIST Handbook 44 (2026), Appendix C: General Tables of Units of Measurement.

Target unit: cubic foot per minute (cfm). One cubic international foot per minute equals exactly 28.316846592 litres per minute. Named variant used: International-foot volume; actual volumetric flow unless another condition is explicitly stated. Reference: National Institute of Standards and Technology: NIST Guide to the SI, Appendix B.9: Factors for Units Listed by Kind of Quantity or Field of Science; National Institute of Standards and Technology: NIST Handbook 44 (2026), Appendix C: General Tables of Units of Measurement.

The gpm-to-cfm direction remains inside the flow rate quantity; it changes the unit label and numerical scale, not the kind of quantity being measured.

Relationship and precision

The named unit relationships are defined or exact, so the conversion is exact before display rounding and source-measurement uncertainty.

• gpm relationship: The terminating base factor is exact for the U.S. liquid gallon and international inch.
• cfm relationship: The terminating factor is exact because the international foot is exactly 0.3048 m and the litre is exactly 10^-3 m³.

To audit the factor through the family base unit, divide the raw dataset factors 3.785411784 by 28.316846592. The generator emits that quotient once at 15 significant digits as the canonical direct factor 0.133680555555556; runtime calculations do not divide the already-emitted base factors again.

Reproducible example

For 10 us gallons per minute, 10 × 0.133680555555556 = 1.33680555555556 cubic feet per minute. Repeating the same multiplication with the stated factor reproduces the displayed conversion before interface rounding.

Directional scale check

Because one US gallon per minute contains 0.133680555555556 cubic feet per minute, the target number is smaller than the source number for every positive input. Zero maps to zero, while negative inputs are rejected because this family models non-negative magnitudes.

Interpretation

Read the result as cubic feet per minute, not us gallons per minute. A value entered as gpm leaves the calculator labelled cfm; this directional distinction matters even when the two units describe the same flow rate quantity.

Assumptions and limitations

• Only non-negative flow magnitudes are accepted; direction is outside this family.
• This family converts non-negative volumetric flow only; it does not convert mass flow, velocity, or total delivered volume without a duration.
• US gallon per minute means the U.S. liquid gallon of exactly 231 cubic inches, not the Imperial gallon.

Common mistakes

• The bare abbreviation gpm is qualified here as U.S. gpm.
• SCFM and ACFM include gas-condition conventions that plain cfm does not encode.

Continue within the Flow Rate family

See the Flow Rate conversion hub for its five-unit reference table and all 20 directed routes.

• Reverse the direction: Cubic feet per minute to US gallons per minute
• Compare another flow rate route: US gallons per minute to Liters per minute
• Compare another flow rate route: US gallons per minute to Liters per second
• Compare another flow rate route: US gallons per minute to Cubic meters per hour
• Compare another flow rate route: Cubic feet per minute to Liters per minute

Assumptions

• The entered value uses us gallons per minute exactly as labelled.
• Only non-negative flow magnitudes are accepted; direction is outside this family.
• Rounding and measurement uncertainty remain the user's responsibility.

Sources and methodology

CalcMotive publishes the formula and assumptions so you can decide whether the estimate fits your use case. See our methodology standards.

• NIST Guide to the SI, Appendix B.9: Factors for Units Listed by Kind of Quantity or Field of Science; National Institute of Standards and Technology; accessed Aug 7, 2026
• NIST Handbook 44 (2026), Appendix C: General Tables of Units of Measurement; National Institute of Standards and Technology; accessed Aug 7, 2026