HealthCalc

Running and cycling

Pace calculator

Three numbers describe any run: how far, how long, and how fast. Give it two and it works out the third — in kilometres or miles, with nothing estimated and nothing rounded into an impossible time.

Method: exact unit arithmetic · no research source needed
I want to know
Unit system
h
min
s

Fill in the two things you know. Pick a distance and a time and the pace follows; a distance and a pace gives the time; a time and a pace gives the distance.

Enter pace in minutes per unit. A box reading "min/km" wants 4.20 for a 4:12 pace, not 4:12 and not 252.

Live
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How to use this calculator

  1. Choose whether you want to find your pace, your time, or your distance.
  2. Enter the two things you already know. Leave the third blank.
  3. Read the result. The panel underneath shows all three quantities once it can.
  4. Copy the link to keep this exact calculation.

A pace is rounded once, to the nearest second, and then split into minutes and seconds. Splitting the parts separately is the common bug: it turns 7.999 into "8:60", which is not a time. This page cannot produce one.

The formula

pace = time ÷ distance
time = pace × distance
distance = time ÷ pace

There is no fitness formula here and nothing to cite. A mile is exactly 1609.344 metres and a kilometre is 1000, so converting between them is arithmetic rather than estimation. Everything is computed internally in seconds per kilometre and converted for display, which is why a 10-minute mile reads as 10:00 per mile and not 6:13.

Why there are no calories on this page

Nearly every pace table online includes an energy column, usually built on the figure 0.03 kcal per kilogram of body weight per metre. That constant has no primary source. It is a rule of thumb repeated until it looked like one.

Real energy expenditure per kilometre varies enormously with body mass, terrain, gradient, pace, and how much of the distance is flat, and it cannot be read off a distance and a time. Rather than publish a number this page cannot stand behind, it leaves energy out. If you want it for what you are actually about to eat, the meal calorie calculator uses real USDA food composition data.

Source

No research source. This page performs unit arithmetic, and the only constants it uses are exact definitions: 1000 metres per kilometre, and 1609.344 metres per international mile, the value fixed by international agreement in 1959 and unchanged since.

The plausibility limits — a pace between roughly 0:15 and 90:00 per kilometre, and a result no longer than 24 hours — are this project's own guard against unit mistakes, not source limits. They exist to catch a decimal slip, not to describe what is achievable.

Frequently asked questions

How do I enter a pace like 4:12?

Type 4.20. The box wants minutes per kilometre in decimals.

What is a good pace?

That is a training question with no single answer, and this page deliberately gives no opinion. Use the heart rate zones for intensity instead.

Why does it refuse a 50-hour result?

Because it is nearly always a units mistake, and showing it would help nobody.