Running Pace Calculator
Calculate running pace, time, or distance from any two of the three — with race-time projections for 5K, 10K, half marathon, and marathon.
That's a pace of 5:00/km (8:03/mi) at an average speed of 12.00 km/h (7.46 mph).
Race times at this pace
Results update as you type. Race projections assume even pace — real race times typically slow slightly over longer distances due to fatigue and hills.
Formula
Three identities: pace = time / distance,
time = pace × distance, and
distance = time / pace. The race
projections multiply your pace per kilometre by the four standard distances (5 km, 10 km,
21.0975 km, 42.195 km).
When this calculator helps
British running culture is unusual in that it lives happily in two unit systems at once, and this calculator is built for exactly that. Use it when you have finished a run and want your pace, when you are planning a parkrun PB or a spring marathon and need a goal time, or when you only know two of the three numbers — pace, time and distance — and want the third worked out for you. It covers everything from a Saturday-morning 5K to a London Marathon target.
It is most useful for the questions UK runners actually ask: what pace do I need to break 25 minutes at parkrun, if I hold 5:30 per kilometre how long will my 10K take, or what does my training-plan 'easy 8 miles' work out to in time. Because pace shows in both minutes per kilometre and minutes per mile, you do not have to keep converting between the parkrun world and the road-race world in your head.
How to read your result
Pace is the headline: time per kilometre or per mile, telling you how fast you are travelling in the unit runners actually plan with. The finish-time projection then multiplies that pace by the race distance, so a steady 5:30 per kilometre over 42.195 kilometres projects to roughly 3 hours 52 minutes for a marathon. The longer the distance, the more a small change in pace swings the finish time.
Treat the projection as a goal-pace ceiling rather than a prediction. It assumes you hold the same pace from start to finish, which almost nobody does — real finishes tend to come in a few percent slower over the shorter distances and noticeably slower over a half or full marathon, because of pace fade, hills and aid stops. Use the number to set your splits, not to guarantee your time.
A worked example
Suppose your parkrun 5K time is 24 minutes. That is a pace of 4:48 per kilometre, or about 7:44 per mile. If you wanted to carry roughly that effort to a 10K, the pure arithmetic projection is around 48 minutes — but most runners would target a touch slower over the longer distance. For a half marathon at a more sustainable 5:15 per kilometre, the projection lands near 1 hour 51 minutes. Switching the same pace into miles, 5:15 per kilometre is about 8:27 per mile, which is the figure you would see on a US-format plan or a treadmill.
Common mistakes to avoid
Most pacing errors come from misreading the projection or mixing up the two unit systems British runners juggle.
- Going out too fast on the first kilometre or mile, then fading — the calculator assumes an even pace you actually have to run.
- Mixing minutes per mile and minutes per kilometre — a 5:30 split means very different things in each, so check which unit your plan or watch is using.
- Ignoring hills, wind and heat, which on a real course cost time the pure arithmetic never accounts for.
- Assuming a marathon is just your 10K pace stretched out — endurance fades faster than the distance multiplies.
Pacing for parkrun and UK races
The UK running calendar leans on two very different fixtures. parkrun is a free, timed 5K run on Saturday mornings at hundreds of locations, and because it is always the same distance it is the natural place to test and chase a pace — most regulars know their 5K time to the second. Big-city road races, led by the London Marathon, are where the longer goals live, and these are often discussed in miles even though parkrun is metric, which is why so many British runners think in both units.
A sensible approach is to use a recent parkrun time to set a realistic pace, then project longer races from it while shaving a little off for fatigue over distance. Switch the calculator between minutes per kilometre and minutes per mile to match whichever your training plan, your club session or your race-day pace band is written in, so you are never doing arithmetic mid-run.
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Frequently asked questions
What's a 'good' running pace?▾
Hugely individual — but rough benchmarks for adult runners: 7:30–9:00/km is a comfortable jog for most beginners; 5:30–6:30/km is solid recreational running pace; 4:30–5:00/km is fit-club-runner territory; under 4:00/km is competitive. Heart-rate-based zone training is more useful than pace targets for most beginners — pace varies with heat, terrain, sleep, and stress more than people expect.
How does my pace translate to a marathon time?▾
Multiply pace per km by 42.195. A 5:00/km pace gives ~3h31; 5:30/km gives ~3h52; 6:00/km gives 4h13. Real marathon times typically run 5–10% slower than pure pace × distance because of pacing fade, hills, and aid-station stops. The calculator gives you the pure-arithmetic projection — treat it as a goal pace ceiling, not an expected finish.
Should I train at my race pace?▾
Most evidence-based plans (Daniels, Pfitzinger, Hudson) recommend training at multiple paces: easy (much slower than race pace, building aerobic base), tempo (around lactate threshold, faster than marathon pace), interval (5K-10K race pace), and only occasionally at goal race pace. Spending all your training at race pace tends to cause stagnation and injury risk.
What's the difference between pace and speed?▾
They're inverses. Pace is time per unit distance (e.g. 5 minutes per kilometre); speed is distance per unit time (e.g. 12 kilometres per hour). Runners typically think in pace — it's easier to plan a race ('I'll run 5:30/km splits') than a speed. Cyclists usually think in speed because they're faster overall and the units sit better.
How do I convert pace per km to pace per mile?▾
Multiply by 1.609 (or look at the result above — both are shown). 5:00/km is ~8:03/mile. 6:00/km is ~9:39/mile. The difference matters because British and American running cultures default to opposite units; treadmills, races, and apps don't always align.
Why does this not factor in heart rate?▾
Pace and heart rate are related but not interchangeable — same pace at different temperatures, hills, or sleep states gives very different heart rates. A pace calculator is just arithmetic. Heart-rate-zone training requires individual data (resting and max HR, ideally a lactate-threshold test) and is its own discipline.