Cubic feet per hour (ft³/h) to Cubic feet per second (ft³/s) conversion

Understanding Cubic feet per hour to Cubic feet per second Conversion

Cubic feet per hour ($ft^3/h$) and cubic feet per second ($ft^3/s$) are both units of volumetric flow rate, used to describe how much volume passes through a system over time. The difference is the time basis: one measures flow over an hour, while the other measures flow over a second.

Converting between these units is useful in fields such as HVAC, gas distribution, water movement, industrial processing, and ventilation design. A value expressed in $ft^3/h$ may be convenient for long-duration system output, while $ft^3/s$ is often more practical for engineering analysis and instantaneous flow comparisons.

Conversion Formula

To convert cubic feet per hour to cubic feet per second, use the verified relationship:

$$1\ ft^3/h = 0.0002777777777778\ ft^3/s$$

So the conversion formula is:

$$ft^3/s = ft^3/h \times 0.0002777777777778$$

For the reverse conversion:

$$1\ ft^3/s = 3600\ ft^3/h$$

Which gives:

$$ft^3/h = ft^3/s \times 3600$$

Step-by-Step Example

Suppose a ventilation system moves $18{,}000\ ft^3/h$ of air.

Write the formula:

$$ft^3/s = ft^3/h \times 0.0002777777777778$$

Substitute the given value:

$$ft^3/s = 18{,}000 \times 0.0002777777777778$$

Calculate:

$$18{,}000\ ft^3/h = 5\ ft^3/s$$

This means a flow rate of $18{,}000$ cubic feet per hour is equal to $5$ cubic feet per second.

Real-World Examples

• A commercial rooftop HVAC unit delivering $7{,}200\ ft^3/h$ of air corresponds to $2\ ft^3/s$.
• An industrial exhaust duct carrying $36{,}000\ ft^3/h$ converts to $10\ ft^3/s$, a scale relevant in factory ventilation.
• A gas handling system rated at $54{,}000\ ft^3/h$ is equivalent to $15\ ft^3/s$.
• A water or air flow process in a plant moving $108{,}000\ ft^3/h$ converts to $30\ ft^3/s$.

Interesting Facts

• Cubic foot is a traditional unit in the U.S. customary and imperial measurement systems, and it remains common in engineering, construction, HVAC, and utility applications. Source: Wikipedia – Cubic foot
• Flow rate units such as cubic feet per second are widely used in hydrology and engineering because they connect a volume measurement directly to elapsed time, making them useful for describing river discharge, duct airflow, and process throughput. Source: Britannica – Flow rate

Because there are $3600$ seconds in one hour, values in $ft^3/h$ become much smaller when expressed in $ft^3/s$. That is why the conversion factor from $ft^3/h$ to $ft^3/s$ is the small decimal $0.0002777777777778$.

In practice, $ft^3/h$ is often seen on equipment ratings, specifications, and utility measurements where hourly totals are convenient. By contrast, $ft^3/s$ is often preferred when analyzing how quickly fluid or air is moving through a pipe, duct, channel, or system at any given moment.

Both units describe the same physical concept: volume per unit time. Only the time interval changes.

This makes the conversion straightforward and purely multiplicative.

For quick reference:

$$ft^3/s = ft^3/h \times 0.0002777777777778$$

And in the opposite direction:

$$ft^3/h = ft^3/s \times 3600$$

These two relationships are exact for this conversion page and can be used for both small and large flow values.

When comparing equipment specifications from different sources, converting to a common unit helps avoid misreading system capacity.

This is especially important in:

• ventilation engineering
• compressed gas systems
• industrial process design
• water conveyance calculations

A standardized unit also makes it easier to compare performance, estimate throughput, and interpret technical documents consistently.

How to Convert Cubic feet per hour to Cubic feet per second

To convert Cubic feet per hour to Cubic feet per second, divide by the number of seconds in one hour. Since both units use cubic feet, only the time unit changes.

1. Write the conversion factor:
   There are $3600$ seconds in $1$ hour, so:

   $$1\ \text{ft}^3/\text{h} = \frac{1}{3600}\ \text{ft}^3/\text{s} = 0.0002777777777778\ \text{ft}^3/\text{s}$$

2. Set up the conversion:
   Multiply the given value by the conversion factor:

   $$25\ \text{ft}^3/\text{h} \times 0.0002777777777778\ \frac{\text{ft}^3/\text{s}}{\text{ft}^3/\text{h}}$$

3. Calculate the value:
   Perform the multiplication:

   $$25 \times 0.0002777777777778 = 0.006944444444444$$

4. Result:

   $$25\ \text{ft}^3/\text{h} = 0.006944444444444\ \text{ft}^3/\text{s}$$

A quick way to remember this conversion is that converting from per hour to per second makes the number much smaller. Always divide by $3600$ when moving from hours to seconds.

What is the formula to convert Cubic feet per hour to Cubic feet per second?

To convert Cubic feet per hour to Cubic feet per second, multiply the flow rate by the verified factor $0.0002777777777778$. The formula is $\text{ft}^3/\text{s} = \text{ft}^3/\text{h} \times 0.0002777777777778$.

How many Cubic feet per second are in 1 Cubic foot per hour?

There are $0.0002777777777778$ Cubic feet per second in $1$ Cubic foot per hour. This is the verified conversion factor used for all calculations on this page.

Why is the value in Cubic feet per second smaller than Cubic feet per hour?

A second is a much shorter unit of time than an hour, so the flow amount per second is numerically smaller when converting from a per-hour rate. Using the verified factor, each $1$ $\text{ft}^3/\text{h}$ becomes $0.0002777777777778$ $\text{ft}^3/\text{s}$.

Where is converting Cubic feet per hour to Cubic feet per second used in real life?

This conversion is useful in HVAC, ventilation, compressed air, and industrial flow measurement where systems may report flow rates in different time units. For example, engineers may convert equipment output from $\text{ft}^3/\text{h}$ to $\text{ft}^3/\text{s}$ to compare with sensor data or design specifications.

How do I convert a larger flow rate from Cubic feet per hour to Cubic feet per second?

Multiply the number of Cubic feet per hour by $0.0002777777777778$. For example, if a system has a flow rate of $x$ $\text{ft}^3/\text{h}$, then the equivalent is $x \times 0.0002777777777778$ $\text{ft}^3/\text{s}$.

Is this conversion factor exact for every ft3/h to ft3/s calculation?

On this page, all conversions use the verified factor $1$ $\text{ft}^3/\text{h} = 0.0002777777777778$ $\text{ft}^3/\text{s}$. Using the same factor consistently ensures accurate and predictable results for any input value.