Speed unit conversion

Speed Conversion Calculator

Convert one nonnegative speed into metres per second, kilometres per hour, miles per hour, knots, and feet per second.

Speed input

Enter a speed and its unit

5 units
Equivalent speeds

Converted values

Converted speeds will appear here

Choose the unit that matches the number you entered.

Table of Contents

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What is Speed Conversion?

A speed conversion changes the unit used to describe a rate of travel while keeping the physical speed the same. This calculator accepts metres per second, kilometres per hour, miles per hour, knots or feet per second and displays the equivalent in every listed unit. It is useful when a weather report, vehicle specification, race result or marine forecast uses an unfamiliar unit.

The number describes speed, not distance. A value such as 60 mph says how much distance would be covered per hour if that rate stayed constant; it does not say that 60 miles have already been travelled. Unit conversions also do not account for acceleration, stops, wind or current.

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How to Use This Calculator

  1. Enter the numeric speed in the Speed value box.
  2. Select the unit that belongs to the entered number. This choice is essential because 20 mph and 20 m/s are different speeds.
  3. Select Calculate to see metres per second, kilometres per hour, miles per hour, knots and feet per second.
  4. Keep the unit beside any value you copy. Results are rounded to two decimal places, so use the original value for repeated technical work.

The calculation first expresses the entry in metres per second, then converts that common value into the other units. Zero is allowed and represents no speed. Negative values are not accepted because this page reports speed as a magnitude rather than velocity with direction.

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Formula Used

The base relationships are 1 mph = 0.44704 m/s, 1 ft/s = 0.3048 m/s, 1 km/h = 1 ÷ 3.6 m/s, and 1 knot = 1,852 ÷ 3,600 m/s. To convert into a target unit, first express the input in metres per second, then divide by the exact target-unit factor. The page rounds each final display to two decimal places.

A knot is one nautical mile per hour. It should never be treated as an ordinary statute mile per hour. These factors change only the unit and do not change the underlying rate.

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Variables Explained

TermMeaning
m/sMetres travelled per second, the SI expression used as the common conversion value.
km/hKilometres travelled per hour, common for road speeds in metric countries.
mphStatute miles travelled per hour.
knotOne nautical mile per hour, widely used in marine and aviation work.
ft/sFeet travelled per second.
SpeedA nonnegative rate of distance per time, without a direction.
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Worked Example

Suppose a road sign or instrument shows 60 mph. Multiplying 60 by 0.44704 gives 26.8224 m/s. From that common value, multiplying by 3.6 gives 96.56064 km/h. Dividing by 0.514444… gives about 52.1386 knots, and dividing by 0.3048 gives exactly 88 ft/s.

The displayed results are therefore 26.82 m/s, 96.56 km/h, 60 mph, 52.14 knots and 88 ft/s. Small differences in another converter usually come from display rounding or an abbreviated knot factor, not from a physical difference in speed.

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Why Use This Calculator?

Equivalent values should describe the same motion. The larger number in km/h does not mean the object became faster; a kilometre and an hour form a different-sized unit from a mile and an hour. For quick checks, mph multiplied by about 1.609 gives km/h, while km/h divided by about 1.609 gives mph.

Choose precision that matches the measurement. Two decimal places can be helpful for calculations, but reporting 96.56 km/h from a dashboard that only reads whole mph may imply more accuracy than the instrument supplied. Marine and aviation decisions may also require direction, wind, current, calibrated airspeed or ground speed; this converter supplies none of those adjustments.

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Common Mistakes

  • Entering a distance such as 100 miles instead of a speed.
  • Selecting mph when the entered number is already in km/h.
  • Reading mph as “metres per hour.”
  • Treating a knot as a mile per hour.
  • Multiplying by 3.6 in the wrong direction.
  • Rounding an intermediate result before making another conversion.
  • Using speed alone when a problem requires velocity and direction.
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Frequently Asked Questions

Does converting speed change how fast something is moving?

No. It replaces one unit with an equivalent number in another unit.

Why is the km/h number larger than the mph number?

A kilometre is shorter than a mile, so more kilometres are covered during the same hour.

What is one knot in miles per hour?

One knot is about 1.15078 mph because a nautical mile is longer than a statute mile.

Can this calculate travel time?

No. Travel time also needs a distance and an assumption about whether speed stays constant.

May I enter zero?

Yes. Zero represents no speed and converts to zero in every unit.

Why are results limited to two decimal places?

The page rounds for readable display. Keep more digits outside the page when a technical task requires them.

Is metres per second the same as kilometres per second?

No. One kilometre is 1,000 metres, so those units differ by a factor of 1,000.

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Sources & References