To convert cubic feet per hour to cubic feet per second, multiply by 0.0002777777778. That factor is the whole relationship: both units measure volumetric flow, so the conversion is a proportion with no offset and no substance-specific constant.
Gas appliance and small-flow rating in the US. The cusec — how American river gauges and water rights report flow.
Standard versus actual volume. Gas flow in CFM depends on pressure and temperature, which is why compressor ratings say SCFM and specify the reference conditions. Converting the number is exact; comparing two ratings measured at different conditions is not. Below the calculator there is a step table for the values people look up most, and a second table putting real volumetric flow figures into cubic feet per second so the number you get has something to be compared against.
The formula
cubic feet per hour- The amount you are converting, in cubic feet per hour
0.000277777777778- The exact number of cubic feet per second in one cubic foot per hour
cubic feet per second- The converted result
How it works, step by step
- Enter the value in cubic feet per hour.
- It is multiplied by 0.000277777777778, the exact factor between the two units.
- The answer is shown in cubic feet per second, with the reverse conversion beneath it.
- Check the reference table if you want a figure of comparable size.
Worked examples
A fire hydrant: 7630 CFH in cubic feet per second
A fire hydrant comes to about 7630 CFH. Multiplying by the factor: 7630 × 0.000277778 = 2.11944 cfs. Dividing the answer back by 0.000277778 returns the figure you started with, which is the quickest way to check you have the factor the right way up.
A bathroom tap: 12.7 CFH in cubic feet per second
At 12.7 CFH (a bathroom tap), the same quantity in cubic feet per second is 12.7 × 0.000277778 = 0.00352778 cfs. One cubic foot per hour is 0.000277778 cubic feet per second, so the numbers shrink as expected.
How to read your score
Frequently asked questions
How many cubic feet per second are in one cubic foot per hour?
Exactly 0.000277777777778. Every figure on this page is that one number multiplied by your input, so the only rounding is at the display step.
What is the formula to convert cubic feet per hour to cubic feet per second?
cubic feet per second = cubic feet per hour × 0.000277777777778. Reversed, cubic feet per hour = cubic feet per second ÷ 0.000277777777778, which is the same as multiplying by 3600.
Which is the bigger unit, the cubic foot per hour or the cubic foot per second?
The cubic foot per second. One cubic foot per hour is only 0.000277778 of a cubic foot per second, so it takes 3600 cubic feet per hour to make one cubic foot per second.
What does this quantity actually measure?
Both units measure volumetric flow. That is why a single factor is enough: there is no temperature offset and no material property involved, unlike conversions that cross between different quantities.
What is a cubic foot per hour?
Gas appliance and small-flow rating in the US.
What is a cubic foot per second?
The cusec — how American river gauges and water rights report flow.
Why does my answer differ from another converter?
Almost always because the other tool rounded the factor before multiplying. This page keeps full double precision through the calculation and rounds only for display, and it prints the factor it used so you can see where any difference came from.
Cubic Feet Per Hour to cubic feet per second reference tables
| Cubic Feet Per Hour | Cubic Feet Per Second |
|---|---|
| 0.5 CFH | 0.000138889 cfs |
| 1 CFH | 0.000277778 cfs |
| 2 CFH | 0.000555556 cfs |
| 3 CFH | 0.000833333 cfs |
| 5 CFH | 0.00138889 cfs |
| 10 CFH | 0.00277778 cfs |
| 20 CFH | 0.00555556 cfs |
| 25 CFH | 0.00694444 cfs |
| 50 CFH | 0.0138889 cfs |
| 75 CFH | 0.0208333 cfs |
| 100 CFH | 0.0277778 cfs |
| 250 CFH | 0.0694444 cfs |
| 500 CFH | 0.138889 cfs |
| 1000 CFH | 0.277778 cfs |
| 5000 CFH | 1.38889 cfs |
Exact factor: 1 cubic foot per hour = 0.000277777777778 cubic feet per second.
| Quantity | CFH | cfs |
|---|---|---|
| A dripping tap | 0.01271 CFH | 3.531e-06 cfs |
| A bathroom tap | 12.71 CFH | 0.003531 cfs |
| A shower head | 20.34 CFH | 0.00565 cfs |
| A garden hose | 38.14 CFH | 0.01059 cfs |
| A fire hydrant | 7628 CFH | 2.119 cfs |
| The Thames at London | 8.264e+06 CFH | 2295 cfs |
Published reference values, converted with the same factor this page uses.