Pace/Running Converter
Convert running paces between min/km and min/mile, calculate race times, and view pace zones. All calculations happen locally — nothing leaves your browser.
How do you convert min/km to min/mile? Multiply the kilometre pace by 1.60934, the number of kilometres in a mile — so 5:00/km becomes 8:03/mile. Pace is the inverse of speed, measuring time per distance rather than distance per time, which is why a smaller number means a faster runner. To go the other way, divide the mile pace by 1.60934; to get speed in kph, divide 3,600 by your pace in seconds per kilometre.
How to Use the Pace Converter
- Choose an input mode — Enter a pace in min/km, a pace in min/mile, or a speed in mph or kph. Speed mode is the one to use for treadmill numbers, which are almost always shown as kph or mph.
- Type the minutes and seconds — Pace fields are split into two boxes, so 5 minutes 30 seconds per kilometre is entered as 5 and 30 rather than 5.5. Everything recalculates as you type.
- Read the three conversions — The cards show the same effort as min/km, min/mile and mph, with kph beside the headline figure, so you can quote a session in whichever unit your club, watch or race uses.
- Pick a race distance — The 5K, 10K, Half and Marathon pills give an estimated finish for that distance at the entered pace, using the official distances of 21.0975 km and 42.195 km.
- Scan the full distance table — The predictor lists 1 mile through marathon at once. Every row assumes you hold the entered pace the whole way, so read the longer rows as targets rather than forecasts.
- Copy or share the result — Copy Result puts the pace on your clipboard, and your inputs are kept in the page URL so a bookmarked link reopens the same scenario.
How Pace Conversion Works
Every conversion on this page comes from one constant: a mile is 1.60934 kilometres, the figure fixed by the international yard and pound agreement of 1959. Because pace is time per distance, converting it scales in the same direction as the distance:
pace per mile = pace per km × 1.60934 pace per km = pace per mile / 1.60934Work in seconds to avoid base-60 mistakes. A 5:00/km pace is 300 seconds; 300 × 1.60934 = 482.8 seconds, which is 8 minutes 3 seconds per mile. Doing the same sum with 5.00 as a decimal gives 8.05 and tempts you to write 8:05, which is two seconds out — a small error, but a whole minute across a marathon.
Pace to speed
Speed is the reciprocal of pace, scaled to an hour. There are 3,600 seconds in an hour, so:
kph = 3600 / pace in seconds per km mph = kph / 1.60934At 5:00/km that is 3600 / 300 = 12.0 kph, or 7.5 mph. This is the conversion that matters on a treadmill, where the console asks for speed while your training plan is written in pace. Finish times work the other way round — the tool multiplies your pace in seconds per kilometre by the race distance in kilometres, using the official 21.0975 km for a half marathon and 42.195 km for a marathon.
| min/km | min/mile | kph | mph | 5K | 10K | Half | Marathon |
|---|---|---|---|---|---|---|---|
| 4:00 | 6:26 | 15.0 | 9.3 | 20:00 | 40:00 | 1:24:23 | 2:48:47 |
| 5:00 | 8:03 | 12.0 | 7.5 | 25:00 | 50:00 | 1:45:29 | 3:30:59 |
| 6:00 | 9:39 | 10.0 | 6.2 | 30:00 | 1:00:00 | 2:06:35 | 4:13:10 |
| 7:00 | 11:16 | 8.6 | 5.3 | 35:00 | 1:10:00 | 2:27:41 | 4:55:22 |
What the Race Predictions Actually Assume
The distance table is deliberately simple: it multiplies your pace by each distance and nothing else. That makes it exact as a pacing tool — if you want to run a 1:45 half, the table tells you which pace holds that line — but it is not a fitness model. It assumes you can hold your current pace all the way to the bottom row, which for most people means far longer than they have ever run at that effort.
The standard way to account for slowing over distance is Peter Riegel's endurance formula, first published in the 1970s, which raises the distance ratio to a fading exponent:
T₂ = T₁ × (D₂ / D₁)^1.06Take a 25:00 5K. Straight multiplication predicts a 3:31 marathon; Riegel predicts about 3:59, and the second figure is far closer to what runners actually manage. The 1.06 exponent itself assumes appropriate training for the longer distance — for someone whose longest run is 10 km, even Riegel is optimistic. Use the table on this page for planning splits at a pace you have already trained for, and treat any jump of more than double the distance as a rough guide.
Predicted times are informational estimates. Terrain, heat, wind, altitude, fuelling and how recently you trained all move a real finish time by more than the arithmetic ever will.
What the Pace Zones Mean
The coloured strip in the widget is a fixed reference legend, not a personalised calculation — it names the five intensities in order so you can see where a session sits. Zone boundaries depend on lactate threshold or heart rate testing, which this tool does not attempt. What the labels describe is consistent across most training systems:
| Zone | Purpose | How it feels |
|---|---|---|
| Z1 Recovery | Blood flow between hard sessions | Conversational, almost too slow to feel useful |
| Z2 Easy | Aerobic base, the bulk of weekly volume | Full sentences without gasping |
| Z3 Tempo | Sustained aerobic strength | Short sentences only; comfortably hard |
| Z4 Threshold | Lactate threshold, roughly one-hour race effort | A few words at a time |
| Z5 VO₂ max | Short intervals for top-end aerobic power | No talking; sustainable for minutes, not hours |
The widely used polarised approach puts roughly 80% of weekly running in Z1–Z2 and the remaining 20% at Z4–Z5, with tempo work used sparingly. The practical trap is that easy runs drift too fast: if you cannot hold a conversation, the run is no longer doing the job it was scheduled for. Converting your target easy pace into whichever unit your watch displays is a simple way to keep that honest.
Frequently Asked Questions
Multiply the kilometre pace by 1.60934, working in seconds rather than decimal minutes. A 5:00/km pace is 300 seconds, and 300 × 1.60934 = 483 seconds, which is 8:03 per mile. Converting the other way divides by the same number: an 8:00/mile pace is 480 / 1.60934 = 298 seconds, or 4:58 per kilometre. The tool does this live in either direction.
They are reciprocals. Pace is time per distance, so a lower number is faster; speed is distance per time, so a higher number is faster. To move between them, divide 3,600 by your pace in seconds per kilometre to get kph — 300 seconds per km is 12.0 kph. Runners and race organisers work in pace; treadmills, bikes and car speedometers work in speed.
The table is exact arithmetic, not a fitness prediction. It multiplies your pace by each distance, so it assumes you hold that pace the whole way. That is realistic when the distance is close to what you already train for and optimistic when it is not. For a genuine step up in distance, apply Riegel's formula — new time = old time × (new distance / old distance) raised to the power 1.06 — which predicts about 3:59 for a marathon from a 25:00 5K, against 3:31 from straight multiplication.
No. The coloured strip is a fixed reference legend showing the five intensities in order, not a calculation from your input. Real zone boundaries come from a lactate threshold test, a recent time trial or heart rate data, none of which this tool collects. Use it to remember what each zone is for, and set actual boundaries from a test or with a coach.
Switch to Speed Input and type the console figure. Most treadmills outside the United States display kph and most inside it display mph, so the same number on the dial means noticeably different speeds depending on where you are running. At 10 kph the pace is 3600 / 10 = 360 seconds, or 6:00 per kilometre; at 10 mph it is 3:44 per kilometre. Belt speed is only as accurate as the machine's calibration, so treat gym treadmills as approximate.
No. All the arithmetic runs in JavaScript on your device and nothing is uploaded, logged or stored on a server. Your inputs are written into the page address so you can bookmark or share a scenario, which happens entirely in the browser — but treat that link as personal if you post it somewhere public.
GPS watches report instantaneous pace, which swings by 20 to 30 seconds per kilometre under trees, between tall buildings or on sharp turns, while this tool works with a single steady figure. Watches also differ in how they smooth the signal and whether auto-pause is running. Compare average pace over a full kilometre or a measured track lap rather than the number on screen at any moment.
Yes. The tool uses the official distances of 21.0975 km (13.1094 miles) and 42.195 km (26.2188 miles) rather than the rounded 21 km and 42 km. The difference sounds trivial but is not: at 5:00/km the extra 195 metres of a marathon is very nearly a full minute, which is enough to miss a round-number target.
Use Cases
Racing Abroad in the Other Unit
A runner who trains in min/km and enters a race with mile markers can convert target splits once, write them on a wristband, and stop doing mental arithmetic at every marker while under pressure.
Building a Marathon Pace Band
Work backwards from a goal time: try paces until the marathon row shows the finish you want, then use that pace as the line to hold through the early kilometres when it feels far too easy.
Setting Treadmill Speed from a Plan
Training plans are written in pace, treadmill consoles ask for kph or mph. Convert the session pace to speed before you step on, so an easy run does not turn into a tempo run by accident.
Choosing a Realistic Race Entry
Before committing to a wave or a cut-off time, check what your current training pace produces over 10K or a half, and compare it against the event's course limit rather than an optimistic guess.
Coaching a Mixed-Unit Group
Coaches and run leaders working with runners from different countries can post one session in both units, so nobody is guessing whether 5:30 means kilometres or miles before an interval set.