US gallons per minute to cubic meters per hour

American fire pumps are rated in gallons per minute; the international fire world sizes the same water in cubic meters per hour. The bridge is 0.22712470704 — the exact m³/h in one US GPM, built from the 231 in³ gallon, the liter, and the hour. A 60 GPM fire pump moves 13.63 m³/h; a 500 GPM fire engine pump is 113.6 m³/h.

1 US gallon per minute = 0.22712470704 cubic meters per hour, and 1 cubic meter per hour = 4.402868 US gallons per minute. Every value on this page scales by the same factor: multiply US gal/min by 0.22712470704. Worked: 10 US gal/min = 2.27124707 m³/h; 100 US gal/min = 22.7124707 m³/h.

By EnginStack Editorial Team | Reviewed against NIST, BIPM and primary-source documentation About →
US gallons per minute
13.62748242 cubic meters per hour
60 US gallons per minute = 13.62748242 cubic meters per hour 60 cubic meters per hour = 264.17205236 US gallons per minute

Verified against NIST Special Publication 811 and BIPM SI definitions. The conversion factor is exact and traceable to the 1959 treaty constants.

US gallons per minute to cubic meters per hour

The factor chains two exact definitions: the US gallon is 3.785411784 liters, and 1 L/min = 0.06 m³/h, so 1 GPM = 3.785411784 × 0.06 = 0.22712470704 m³/h. Fire protection, chiller water loops, and industrial water supply all cross this boundary when an American spec meets an international one — and because both anchors are definitions, the factor is exact to eleven digits.

cubic meters per hour = US gallons per minute × 0.22712470704
1 GPM = 0.22712470704 m³/h — the 231 in³ gallon × 0.06
The factor is exact from both definitions.

Worked Examples

Example 1: Convert one fire-truck pump line of 250 GPM

250 × 0.22712470704 = 56.78 m³/h

Example 2: Convert a 20 GPM booster pump

20 × 0.22712470704 = 4.54 m³/h

Example 3: Convert a 1,500 GPM industrial fire main

1,500 × 0.22712470704 = 340.69 m³/h

Common US gallons per minute to cubic meters per hour Conversions

US gallons per minutecubic meters per hourContext
1 GPM0.2271 m³/hThe definitional anchor.
60 GPM13.63 m³/hA fire truck's pump.
100 GPM22.71 m³/hA sprinkler system demand.
500 GPM113.6 m³/hA fire engine pump.
1,000 GPM227.1 m³/hA large industrial fire main.

Engineering Context

This page sits at the junction of three families: the gallons to cubic meters volume anchor, the time family's hour, and the pressure hub's fire-flow requirements. The m³/h to GPM page runs it backward, and the flow rate hub collects all ten converters. Fire pumps in particular tie flow to pressure on every rating curve.

Fire protection is where this pairing earns its keep. North American sprinkler and standpipe design states demand in gallons per minute, while a municipal supply, a storage tank, or a pump curve from a SI-market manufacturer is stated in cubic meters per hour. Both sides then have to be compared against the same hydraulic calculation, and hydraulic calculations do not tolerate a unit stitch: the pump curve is nonlinear, so a 22 percent slip in flow at the nominal point can move the operating point far enough to change the pressure at the most remote head. Keep the factor exact and let the rounding happen once, at the end.

More: m³/h to GPM · GPM to L/min · gal to m³ · Flow Rate Guide · Flow Rate Hub

Related Unit Converters

cubic meters per hour to US gallons per minute US gallons per minute to liters per minute gallons to cubic meters Flow Rate Conversion Guide Flow Rate Converters

Frequently Asked Questions

How many m³/h is 1 GPM?

Exactly 0.22712470704. One US gallon is 3.785411784 L, and 1 L/min = 0.06 m³/h, so 1 GPM = 3.785411784 × 0.06 m³/h.

Why does fire protection use GPM in the US?

Because US fire codes and pump ratings were built on the gallon; international standards quote m³/h or L/min. A 500 GPM fire pump and a 113.6 m³/h pump are the same machine with two labels.

How do I convert GPM to m³/h by hand?

Multiply by 0.227 for a mental estimate, or divide by 4.4028675393 — the exact reciprocal — for spec-level work.