m/s to km/h to Feet: Speed Conversion Calculator

This calculator converts a speed in metres per second (m/s) or kilometres per hour (km/h) into feet per second (ft/s), and can also convert between the metric speed units. Enter a speed and choose its starting unit to see the equivalent speed in the other units.

Formula

The calculator first expresses the entered speed in metres per second, then converts that value into feet per second and kilometres per hour. The formulas are:

• Metres per second: speed in m/s = entered speed × unit factor.
• Feet per second: speed in ft/s = speed in m/s × 3.28083989501312.
• Kilometres per hour: speed in km/h = speed in m/s × 3.6.

Here, speed is the non-negative number you enter, without a unit attached. The selected unit factor is 1 for m/s and 3.6 for km/h. The conversion factor 3.28083989501312 expresses the number of feet in one metre; 3.6 follows from 1 hour = 3,600 seconds and 1 kilometre = 1,000 metres. Results are rounded to two decimal places.

Worked Example

With the default entry of 10 and the default starting unit of m/s, the unit factor is 1:

1. Convert to m/s: 10 × 1 = 10.00 m/s.
2. Convert to ft/s: 10 × 1 × 3.28083989501312 = 32.8083989501312, which rounds to 32.81 ft/s.
3. Convert to km/h: 10 × 1 × 3.6 = 36.00 km/h.

So 10 m/s is 32.81 ft/s, or 36 km/h. The outputs describe the same speed in different units; the physical speed does not change.

How the Conversion Works

Speed is distance divided by time. Metres per second tells you how many metres are covered in one second, while kilometres per hour tells you how many kilometres are covered in an hour. Feet per second uses feet as the distance unit but keeps the time unit as seconds.

To go directly between the metric units, multiply m/s by 3.6 to get km/h. To reverse that conversion, divide km/h by 3.6. For feet per second, multiply m/s by approximately 3.28084. If starting with km/h, either divide by 3.6 first and then convert to ft/s, or use the combined factor: 1 km/h is approximately 0.911344 ft/s.

• m/s to km/h: multiply by 3.6.
• km/h to m/s: divide by 3.6.
• m/s to ft/s: multiply by 3.28084.
• km/h to ft/s: multiply by about 0.911344.

Why “Feet” Needs a Time Unit

A speed cannot be converted to feet alone. Feet measure distance; a speed also includes how long that distance takes. The relevant customary-unit result here is feet per second (ft/s), not just feet. For example, 10 m/s does not mean that an object is 32.81 feet long. It means that, at that speed, it travels about 32.81 feet each second.

If you need a distance in feet rather than a speed, you also need a duration. Multiply the speed in ft/s by elapsed time in seconds to find distance in feet, assuming the speed is constant. For instance, travelling at 10 m/s for 5 seconds covers 50 metres, or about 164.04 feet. If speed changes during the interval, the average speed or a more detailed motion calculation is needed.

When to Use Each Unit

Metres per second is common in scientific and technical descriptions because it uses the SI base units for length and time. Kilometres per hour is familiar for everyday travel speeds in places that use the metric system. Feet per second is useful when a measurement or reference uses customary units, such as a distance stated in feet and a time in seconds.

Choose the result that matches the context of the value you are comparing. Do not compare a number in ft/s directly with a number in km/h: convert one first. Also check whether a source gives a speed in miles per hour (mph). Miles and feet are both customary distance units, but mph is not the same as ft/s. One mph is approximately 1.46667 ft/s, so the calculator’s km/h option should not be used as a substitute for mph.

Common Conversion Mistakes and Limits

• Multiplying by the wrong factor: To convert m/s to km/h, multiply by 3.6; to convert km/h to m/s, divide by 3.6.
• Dropping “per second” or “per hour”: A converted speed remains a distance-per-time quantity.
• Rounding too early: Keep several digits during intermediate calculations, then round the final result. This calculator displays two decimal places.
• Mixing up decimal conventions: Enter a decimal point if that is what the calculator accepts; do not use a thousands separator that could be read as a decimal mark.
• Assuming a constant speed: The conversion changes units only. It does not calculate acceleration, travel time, or distance.

The conversion factors are exact as defined by the metre-to-foot relationship and the hour-to-second relationship, but displayed values are rounded. Small differences in the last displayed digit can result from rounding or from using a shorter factor in another calculator. The calculations also assume the input is a valid, non-negative speed; negative values may represent a direction in some technical systems, but this simple converter treats speed as magnitude.

Frequently Asked Questions

How many feet per second is 1 m/s?
One metre per second is approximately 3.28084 feet per second. Rounded to two decimal places, that is 3.28 ft/s.

How do I convert km/h to ft/s?
Multiply the km/h value by approximately 0.911344. For example, 36 km/h is about 32.81 ft/s.

How do I convert m/s to km/h?
Multiply the m/s value by 3.6. For example, 10 m/s equals 36 km/h.

Is ft/s the same as feet?
No. Feet measure distance, while feet per second measure speed: distance travelled for each second.

Can this calculator convert mph?
No. It accepts m/s or km/h. To convert mph to ft/s, multiply the mph value by approximately 1.46667, or first convert mph to one of the calculator’s supported units.

Related

• Feet to Miles Calculator: Convert Distance
• Feet and Inches to Meters Calculator
• Convert mph to fps (Feet per Second)

in speed | Speed | - | 10 | 0
sel unit | Starting unit | m/s=1, km/h=3.6
out fps | Speed in feet per second | ft/s | speed * unit * 3.28083989501312 | 2
out ms | Speed in metres per second | m/s | speed * unit | 2
out kmh | Speed in kilometres per hour | km/h | speed * unit * 3.6 | 2