Loading page
About this tool
Work out your pace per kilometre and speed from a distance and finish time.
The Running Pace Calculator turns a distance and a finish time into your pace per kilometre (time ÷ distance), your pace per mile using the exact 1.609344 conversion, and your average speed in km/h. It then projects finish times for 5K, 10K, the half marathon at 21.0975 km and the marathon at 42.195 km if you held that same pace throughout. It is for runners checking what today's session actually means for race day, in the units the race clock uses.
Open Running Pace Calculator on AltFTool — it loads instantly in your browser.
Enter the values you already know.
Fine-tune the options to match your scenario.
Read the result and use it in your planning or reporting.
Gives pace per km and per mile side by side using the exact 1.609344 km-per-mile factor, so the two never drift apart.
Projects against the official 21.0975 km and 42.195 km distances rather than a rounded 21 and 42.
The projections assume you hold the same average pace throughout, which is the honest reading of a flat pace calculation.
Divide total time by distance: 30 minutes over 5 km is 6.0 minutes per km, shown as 6:00/km. Multiply that by 1.609344 to get pace per mile — in this case about 9:39/mile — and divide distance by time in hours for speed, here 10.00 km/h.
Roughly 5:41 per kilometre, or about 9:09 per mile, across the full 42.195 km. Enter 42.195 km and 240 minutes to see it, and remember that most runners target a slightly faster pace early to leave a buffer.
They assume you hold your current average pace for the whole distance, which almost never happens over longer races — pace usually slows as distance grows. Fatigue-adjusted models such as Riegel's, which scales time by (new distance ÷ old distance) raised to about 1.06, predict longer races more conservatively. Treat these projections as an upper bound on what today's pace implies.
Pace is time per unit distance (minutes per km) and speed is distance per unit time (km/h), so they move in opposite directions — a faster run has a lower pace number and a higher speed. A 6:00/km pace is 10.00 km/h; 5:00/km is 12.00 km/h.
Add the Running Pace Calculator widget to your blog or website — free, responsive, no signup. Just keep the “Widget by AltFTool” credit link visible.
<iframe src="https://www.altftool.com/embed/widget/running-pace-calculator"
title="Running Pace Calculator — free AltFTool widget"
width="100%" height="640" style="border:0;border-radius:12px;overflow:hidden"
loading="lazy" referrerpolicy="no-referrer-when-downgrade" allow="clipboard-write"></iframe>
<p style="font-size:12px;margin:4px 0 0">Widget by <a href="https://www.altftool.com/tools/all/running-pace-calculator?utm_source=embed&utm_medium=widget" rel="nofollow">AltFTool — free online tools</a></p>