Running Pace Calculator

Solve for pace, finish time, or distance — with mile & km splits

Enter distance and pace — we'll give your finish time.

Time (hh : mm : ss)
: :
Pace (mm : ss per unit)
:
Finish time
0:00:00
at pace

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<iframe src="https://snaptoolsuite.com/running-pace-calculator/?embed=1"
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  title="Running Pace Calculator" loading="lazy"></iframe>
<p>Free <a href="https://snaptoolsuite.com/running-pace-calculator/">Running Pace Calculator</a> by Snap Tool Suite</p>
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Running Pace Calculator — guide & how to use

What it does

This running pace calculator is bidirectional: pick the one variable you want to solve for — finish time, pace, or distance — and enter the other two. It returns pace in both min/mi and min/km, speed in both mph and km/h, and a full mile-and-kilometer split table so you can build a printable race plan. All math runs privately in your browser using the exact conversion 1 mile = 1609.344 m and certified race distances.

How to use it

  1. Pick what to solve for: Time, Pace, or Distance.
  2. Fill in the other two values (choose a 5K / 10K / Half / Marathon preset or a custom distance).
  3. Read your answer, the both-unit pace & speed, and your split table.

Worked example

You want to break 2 hours in the half marathon. Set Solve for → Pace, choose the Half Marathon preset (13.1094 mi / 21.0975 km), and enter a time of 2 : 00 : 00. The math: pace = time ÷ distance = 7200 s ÷ 13.1094 mi = 549.2 s/mi ≈ 9:09 per mile (5:41 per km, about 6.56 mph). Flip to Solve for → Time with a 9:09/mi pace and you get the 2:00:00 finish back — pace and time are exact inverses scaled by the distance.

The formulas (all math is done in metric, then converted)

Every distance becomes meters and every time becomes seconds before any division, so rounding never compounds:

1 mile = 1609.344 m (exact)   1 km = 1000 m
time(s)  = hh*3600 + mm*60 + ss
SOLVE TIME:  T = pace_per_unit * (D_meters / unit_length_m)
SOLVE PACE:  pace_per_unit = T * unit_length_m / D_meters
SOLVE DIST:  D_meters = T * unit_length_m / pace_per_unit
speed_mph  = (D_meters/1609.344) / (T/3600)
speed_kmh  = (D_meters/1000)     / (T/3600)
Round ONCE at display: time→nearest second, pace→nearest second, speed→2 dp.

How to embed this tool on your website

No account, no coding. Copy the embed code above and paste it where you want the calculator to appear.

See it live: view a real embed example →

Accuracy & what this tool is not

This is a unit / arithmetic converter, not coaching or medical advice. Splits are derived from the unrounded internal pace, so they always sum to the headline total. A few honest notes:

Frequently asked questions

How do I calculate my running pace?

Pace = time ÷ distance. Divide finish time by distance for time per mile or per km. This tool does it both ways and shows min/mi and min/km.

What pace do I need for a 2-hour half marathon?

About 9:09 per mile (5:41 per km, ~6.56 mph) over the certified 13.1094 mi / 21.0975 km.

What's the difference between pace and speed?

They're reciprocals. Faster running means a LOWER pace number but a HIGHER speed number. This tool shows both.

Is a half marathon really 13.1 miles?

It's 21.0975 km = 13.1094 mi; a marathon is 42.195 km = 26.2188 mi. We use the exact certified values.

Can it predict my marathon time from a 5K?

It shows same-pace equivalents, but those assume constant pace — not a true prediction. Use Riegel or VDOT for that.

Is it really free?

Yes. 100% free, everything runs in your browser. Nothing is stored or sold.

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Private: everything is calculated in your browser. We don't store or sell your data. For planning only — not coaching or medical advice.