What is the exact conversion factor from CFM to GPM?

1 cubic foot per minute equals exactly 7.48051948 US gallons per minute. This comes from the definition of the US liquid gallon: 1 ft³ contains exactly 7.48051948 US gallons.

Is GPM here US gallons or UK (imperial) gallons?

This converter uses US liquid gallons. 1 cubic foot = 7.48051948 US gallons. For UK imperial gallons the factor is 1 ft³ ≈ 6.22883545 imperial gallons, giving a different CFM-to-IGPM ratio.

How do I convert GPM back to CFM?

Divide the GPM value by 7.48051948. For example, 100 GPM ÷ 7.48051948 ≈ 13.368 CFM. The reverse field on this page does this automatically.

Why is CFM used for air but GPM for water?

In US engineering, CFM (cubic feet per minute) is the standard for air flow — in HVAC ductwork and compressors. GPM is used for liquid flow — pumps, plumbing, and fire systems. When a system uses both (e.g., a cooling coil), engineers convert between units to compare air-side and water-side capacities.

What is a typical HVAC air handler flow in both units?

A residential 3-ton air handler moves roughly 1,200 CFM of air, which equals about 8,977 GPM if treated as a volume flow — though that figure only becomes meaningful for liquid-side comparisons, not direct air-to-water comparison.

CFM to GPM Converter

Name: CFM to GPM Converter
Availability: InStock
Author: Nham Vu

Enter a flow rate in cubic feet per minute (CFM) and get the equivalent in US gallons per minute (GPM) instantly, with a reverse converter and reference table.

Flow Rate Converter

Cubic feet per minute (CFM)

= — US gallons per minute (GPM)

US gallons per minute (GPM) — reverse

= — cubic feet per minute (CFM)

1 CFM = 7.48051948 US GPM | 1 GPM = 0.13368056 CFM

Common conversions

CFM	GPM (US)	Typical use

Summary

Enter a flow rate in cubic feet per minute (CFM) and get the equivalent in US gallons per minute (GPM) instantly, with a reverse converter and reference table.

How it works

Enter a flow rate value in cubic feet per minute (CFM) in the top field.
The converter multiplies by 7.48051948 — the number of US gallons in one cubic foot — to produce GPM.
The GPM result appears instantly with no button press needed.
Use the reverse field to convert GPM back to CFM.
Click any row in the reference table to load that value into the converter.

Use cases

Convert HVAC air handler or chilled-water flow specs from CFM to GPM for pump sizing.
Match duct and pipe flow rates when crossing between air-volume and liquid-volume units.
Verify fire suppression system delivery rates stated in CFM against GPM sprinkler specs.
Convert compressor discharge flow from CFM to GPM for downstream liquid system calculations.
Cross-check industrial process flow data between volumetric unit standards.
Compare waterfall or fountain pump output given in CFM against GPM-rated equipment.
Translate well or aquifer yield tests reported in CFM to the GPM format used by pump curves.

Frequently Asked Questions

Last updated: 2026-07-22 · Reviewed by Nham Vu