Speed Converter

Convert a speed between mph, km/h, m/s, knots, and many more units.

Supports 21 speed units, the Beaufort scale, and 20 running pace units.

Updated August 21, 2026

CreatorFrank Zhao

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Introduction / overview

The Speed Converter turns any speed you type into every other speed — and the running pace that goes with it. One number in, sixteen results out, across four groups: Imperial/US, Metric, Other, and Run pace.

It covers 21 linear speed units from feet per day to light speed, the Beaufort wind scale, and 20 pace units from milliseconds per meter to minutes:seconds per mile. You can also enter pace directly and read speed back the other way. Good for road trips, flight plans, sailing, cycling, and everyday running math.

Type in any box — miles per hour, meters per second, knots, or even your 5:00 per mile pace — and every other field updates automatically. Edit a different field to convert the other direction.

Who is this for?

Drivers and travelers switching between mph and km/h, or checking how a US speed limit reads abroad.
Runners and coaches flipping between speed and pace — for example km/h to min:sec per km or per mile.
Pilots, sailors, and outdoor folks who work in knots, Beaufort, or light-speed fractions.

Conversions run through meters per second using exact definitions — one foot is exactly $0.3048\ \mathrm{m}$ , one mile exactly $1609.344\ \mathrm{m}$ , one knot exactly $1852\ \mathrm{m/h}$ — so results are consistent no matter which direction you convert. If you need speed from distance and time instead of unit to unit, our Velocity Calculator does that step for you.

How to use / quick start

1Type the speed or pace you know into its natural box — for example Miles per hour or Minutes per km and seconds per km.
2Need a unit not on its own row? Open the More imperial/US units, More metric units, or More pace units menus — they hold the full lists (10 imperial, 9 metric, 20 pace units).
3For pace, use the compound boxes min/mile–sec/mile or min/km–sec/km when your watch shows 5:30 — just type $5$ and $30$ side by side.
4Read the rest as they fill. Edit any other field to flip the direction — whatever you type becomes the source and everything else re-derives from it.

Worked example — highway speed: what is 60 mph in metric, knots, and pace?

60\ \mathrm{mph}

=

60 \times 0.44704

=

26.8224\ \mathrm{m/s}

\frac{26.8224 \times 3.6}{1}

=

96.56\ \mathrm{km/h}

52.14\ \mathrm{kn}

1{:}00\ \mathrm{/mile}

Type $60$ into Miles per hour. The converter shows 26.8224 m/s, 96.56 km/h, about 88 ft/s, 52.14 knots, and a running pace near 1:00 per mile. Switching More imperial/US units to feet per minute gives 5,280 ft/min — a quick sanity check for 60 mph in one hour.

Worked example — running pace: what speed is 5:30 per kilometer?

5{:}30\ \mathrm{/km}

=

330\ \mathrm{s/km}

\frac{1000}{330}

\approx

3.03\ \mathrm{m/s}

10.91\ \mathrm{km/h}

6.78\ \mathrm{mph}

In the Minutes per km and seconds per km row type $5$ and $30$ side by side. That is 330 seconds for 1000 m, so $v = 1000/330 \approx 3.03\ \mathrm{m/s}$ — about 10.91 km/h or 6.78 mph. The Seconds per 100m field shows 33.0 s per 100 m.

How to read the results

The number you typed stays in its normal color; the auto-filled values appear in blue so you always see which one is the source.
Long results are rounded for display — for example $1\ \mathrm{m/s} \approx 2.23694\ \mathrm{mph}$ — while the conversion keeps full accuracy behind the scenes.

Real-world examples

From knots on the chart to mph on the road

A harbor forecast says 20 knots. Is that like driving speed? Type $20$ into Knots:

20\ \mathrm{kn}

= 20 \times \frac{1852}{3600}

\approx

10.29\ \mathrm{m/s}

\approx

23.02\ \mathrm{mph}

So a 20-knot wind is about 23 mph — brisk enough to make cycling into it noticeably harder, but well below Beaufort gale force.

Training target: hold 4:00 per km. What is that as speed?

Your plan asks for 4 minutes per kilometer. In Minutes per km and seconds per km type $4$ and $0$ :

4{:}00\ \mathrm{/km}

= 240\ \mathrm{s/km}

v = \frac{1000}{240}

= 4.167\ \mathrm{m/s}

= 15.0\ \mathrm{km/h}

That is 6:26 per mile — use the Minutes per mile and seconds per mile row to check, or set the treadmill to 15 km/h and keep it.

Putting light speed in perspective

Pick Light speed and type $0.01$ — one percent of $c$ :

0.01\,c

= 0.01 \times 299\,792\,458

\approx

2\,997\,925\ \mathrm{m/s}

\approx

6\,706\,000\ \mathrm{mph}

Even 1% of light speed would lap Earth in about 13 seconds — a vivid reminder why everyday units like m/s and km/h are best for Earth-scale trips, and fractions of $c$ make sense only for physics or astronomy. Try $1\,c$ itself and every other field will show the exact equivalents.

Tips & best practices

Type in the unit you were given

Don’t do a mental conversion first. If the sign says km/h, type into Kilometers per hour and let the mph box answer — one less place to slip a decimal.

Use the compound pace boxes

For 5 min 30 s per mile, use the Minutes per mile and seconds per mile row so the two parts stay one value. Afterward the More pace units menu offers 20 other pace formats without retyping.

Watch the “mile” trap

A statute mile is 1,609.344 m; a nautical mile is 1,852 m — about 15% longer. Pace per mile uses the statute mile. When charts say knots or nautical miles, switch to the Knots row.

Treat Beaufort as an estimate

Beaufort force uses an empirical curve, not a legal definition. It’s great for naming wind conditions, but convert the underlying m/s or knots when you need a precise number.

Getting the most accurate result

Enter as many digits as you have. The conversion itself uses exact definitions where they exist, so the result is only as precise as your input.
Keep one system for a whole project. Mixing km/h in one place and mph in another is the most common source of confusion.
When comparing devices from different countries, convert both to meters per second first, then judge.

Calculation method / formula explanation

The converter first turns your number into meters per second, then into the target unit — so any two speed units can talk to each other without a separate formula for each pair. Running pace is the reciprocal of speed, and Beaufort uses its own curve. All of it is bidirectional: edit any field and the rest follow.

The general speed conversion

V_t = V_s \times \frac{f_s}{f_t}

where $V_s$ is the value in the source unit, $V_t$ is the value in the target unit, $f_s$ is meters per second per source unit, and $f_t$ is meters per second per target unit.

Speed to running pace

p_{\mathrm{min/m}} = \frac{1}{60\,V_{\mathrm{m/s}}}

where $p_{\mathrm{min/m}}$ is the pace in minutes per meter and $V_{\mathrm{m/s}}$ is the speed in meters per second. Other pace units are linear multiples of minutes per meter — for example sec/mile is $96560.64 \times p_{\mathrm{min/m}}$ .

Beaufort wind scale approximation

B = \left(\frac{V_{\mathrm{m/s}}}{0.836}\right)^{2/3},\quad V_{\mathrm{m/s}} = 0.836\,B^{3/2}

$B$ is the Beaufort force. The constant $0.836$ is an empirical fit, not a legal definition — use knots or m/s when you need an exact wind speed.

Exact definitions behind the units

Unit	Exact value in meters per second
foot (international)	0.3048
inch	0.0254
mile	1609.344 / 3600 = 0.44704
nautical mile / knot	1852 / 3600 = 463 / 900
kilometer per hour	1000 / 3600 = 5 / 18
light speed (c)	299,792,458

One light speed is exactly 299,792,458 m/s by SI definition; the rest follow from exact length definitions.

A quick sanity check — 60 mph to km/h and to pace

60\ \mathrm{mph}

=

60 \times 0.44704

=

26.8224\ \mathrm{m/s}

26.8224 \times 3.6

=

96.56\ \mathrm{km/h}

p_{\mathrm{min/m}} = \frac{1}{60 \times 26.8224}

\approx

0.000621\ \mathrm{min/m}

60\ \mathrm{s/mile}

1{:}00\ \mathrm{/mile}

Variable guide

$V_s$

Numeric speed in the source unit

$V_t$

Numeric speed in the target unit

$f_s$

Meters per second per source unit

$f_t$

Meters per second per target unit

$p_{\mathrm{min/m}}$

Running pace in minutes per meter

$B$

Beaufort wind force

Frequently asked questions

Can I enter pace to get speed?

Yes. The speed↔pace link is two-way. Type a pace in any pace row — for example $6{:}00\ \mathrm{/mile}$ — and the speed rows update to about 6 mph, and the other pace formats like per km update too. Edit a speed field to flip it back.

How do I enter a pace like 5:30 per mile?

Use the compound rows. In Minutes per mile and seconds per mile, type $5$ in the first box (labeled min/mile) and $30$ in the second (sec/mile). The same pattern works for Minutes per km and seconds per km with min/km and sec/km.

Why is pace blank when speed is zero?

Pace is time per distance: $p = 1/(60\,V)$ . At 0 m/s you never cover the distance, so pace has no finite value — the pace boxes stay blank until you enter a positive speed or pace. The reverse is true too: a pace of zero would imply infinite speed.

How accurate is the Beaufort number?

It follows the widely used curve $B = (V/0.836)^{2/3}$ with $V$ in m/s. That is an empirical fit for naming wind, not a legal definition. For navigation or engineering, read the knots or m/s value instead. Entering a negative Beaufort is not meaningful and the field will flag it.

Why do some results show fewer decimal places?

Conversions like $1\ \mathrm{m/s} \approx 2.23694\ \mathrm{mph}$ go on forever. The display rounds for readability, while the conversion keeps full accuracy. Your typed value is never shortened — the other boxes do the rounding.

Limitations / disclaimers

This is a unit conversion tool — the math follows exact definitions where they exist. A few practical boundaries are worth knowing:

•Speed and pace are treated as magnitudes, so negative values are flagged. Clear the box and re-enter a positive number.
•Beaufort force is an empirical approximation ( $0.836\,B^{3/2}$ ) for naming wind conditions, not a legal threshold. For precise work, use knots or meters per second.
•Pace has no finite value at zero speed. The pace boxes stay blank when speed is zero — enter a positive speed or pace instead.
•Displayed numbers are rounded for readability; your typed value is kept at full accuracy for the conversion. No extra “precision” control is needed.

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