Running Pace & Speed Calculator
Calculate running pace, speed, finish time, or distance for any race. Works with km and miles.
How running pace, speed and finish time relate
Pace, speed and time are three views of the same thing. If you know any two, the third falls out:
- Pace is time per unit of distance (min/km or min/mi).
- Speed is distance per unit of time (km/h or mph).
- Time is pace × distance.
A 5:00 min/km pace equals 12 km/h. A 4:00 min/km pace equals 15 km/h. Every 30 seconds you shave off your per-kilometre pace corresponds to roughly 1.2–1.5 km/h more speed at typical amateur ranges.
Common training pace zones
Coaches usually split running efforts into five broad zones, expressed as a percentage of your current 5K race pace. This calculator will give you one pace — a good starting point for figuring out your other zones is:
| Zone | Feel | Rough pace vs 5K |
|---|---|---|
| Recovery / easy | Conversational, could sing | +90 to +120 sec/km |
| Aerobic / long run | Talk in short sentences | +60 to +90 sec/km |
| Marathon pace | Comfortably hard | +30 to +45 sec/km |
| Threshold / tempo | Uncomfortable, sustainable ~1h | +15 to +25 sec/km |
| VO2 max / intervals | Hard, only for short bursts | -5 to -15 sec/km faster than 5K |
These are rough starting points; individual physiology varies. Heart-rate or perceived-effort feedback beats sticking rigidly to a paces table.
How the race-time predictions here work
The "Predicted race times at this pace" table assumes you can hold the entered pace for every distance shown. This is deliberately simple — real-world race times decay with distance because of accumulated fatigue, fuelling, heat and pacing errors. Two well-known formulas that model this decay are:
- Riegel's formula: T₂ = T₁ × (D₂ / D₁)1.06. Simple and reasonably accurate for well-trained runners moving from a shorter to a slightly longer distance.
- Cameron's formula: a more nuanced adjustment that performs better for extrapolating from a 5K or 10K out to a marathon.
For everyday planning — pacing an easy long run or setting a target finish time — the straight-line assumption in this calculator is close enough. For serious goal-setting on longer distances, use a race equivalency table or trust a recent race result.
Common mistakes when calculating pace
- Mixing kilometres and miles. Switching the unit dropdown mid-calculation is fine; entering a mile distance while the pace unit is set to km/mi will give a nonsense number. Check the label next to each field.
- Forgetting that "10K" is 10 kilometres, not 10 miles. A 45-minute 10K (4:30 min/km) is a very different effort from a 45-minute 10-mile run (2:48 min/km, which is faster than any human alive).
- Comparing race times across different courses. Elevation, wind and surface change pace by 5–15 seconds per km. A "PB" on a hilly, technical course may be a bigger achievement than a faster time on a fast, flat road course.
- Chasing marathon pace on every run. If more than 20% of your weekly mileage is at threshold or faster, you are training your legs to break down, not adapt.
Frequently asked questions
What is a good running pace?
"Good" is entirely relative to your training age, recent volume and goals. A common milestone for a healthy adult with a few months of consistent training is a sub-30-minute 5K (roughly 6:00 min/km). Sub-20-minute 5K (4:00 min/km) is a serious amateur benchmark. Sub-15-minute 5K is elite territory.
How do I convert pace to speed?
Speed (km/h) = 60 ÷ pace (min/km). So 5:00 min/km ÷ into 60 = 12 km/h. In imperial: speed (mph) = 60 ÷ pace (min/mi). The calculator above does this for you and shows both units.
Why does my GPS watch show a different pace than this calculator?
GPS watches average pace across short segments. If you slow at a crossing, the watch pace lags reality by a few seconds. This calculator uses total distance ÷ total time — the "true" average pace of the whole effort, which is what race results measure.
Can I use this for cycling or swimming?
The maths works for any constant-effort activity, but the race-time predictions and zone table are calibrated for running. For cycling, watts and heart-rate zones are more useful than pace. For swimming, pace is usually expressed per 100 m — same idea, different unit.
How accurate are the predicted race times?
The predictions here assume you hold the entered pace exactly across every distance. Reality: your 5K pace is faster than your marathon pace. Treat the table as an upper bound for longer distances — a "if I could hold this pace forever, this is what I would run" answer.