Calculate running pace, time, or distance with race time predictions for 5K, 10K, half & full marathon.
A complete pace calculator for runners, cyclists, and walkers. Enter any two of distance, time, and pace to instantly compute the third — with side-by-side metric/imperial conversion, color-coded training zones (easy, marathon, threshold, interval, sprint), race time predictions for popular distances, and split-by-split breakdowns. Results update in real time as you type, with no submit button.
Pace is the single most useful metric in endurance training. Unlike heart rate, which drifts with heat and fatigue, or perceived effort, which is subjective, pace gives you an objective, repeatable benchmark for every workout. Tracking pace across weeks and months reveals real fitness trends — whether your easy runs are getting faster at the same effort, whether your tempo pace is sustainable, and whether your goal race time is realistic. Most modern training plans (Daniels, Pfitzinger, Hansons) prescribe workouts in pace ranges rather than fixed splits.
The five-zone model on this page mirrors what coaches use worldwide. Easy pace (slower than 7:00/km for most runners) builds capillaries and mitochondrial density without accumulating fatigue — it should feel conversational. Marathon pace is your sustainable race effort, sitting just below your lactate threshold. Threshold or tempo pace is the fastest pace you can hold for ~60 minutes; it raises the speed at which lactate accumulates. Interval pace targets VO2 max with hard 3-5 minute repetitions, while sprint pace is reserved for short anaerobic bursts.
Our race predictor projects your current pace linearly across 5K, 10K, half marathon, and full marathon. This is a useful upper bound — if you can hold 5:00/km for a 10K, you cannot necessarily hold it for a marathon. Physiological models like Riegel formula apply a fade factor (typically 1.06) to account for fatigue at longer distances, meaning a true marathon time is usually 5-10% slower than the linear projection.
Pace = total time ÷ distance. For example, running 10 km in 50 minutes gives 5:00 per km. Our tool handles all three directions: pace from time + distance, time from pace + distance, or distance from time + pace.
Multiply min/km by 1.60934. So 5:00/km equals roughly 8:03/mile. The calculator shows both side-by-side automatically.
They are linear projections — they assume you can hold the entered pace for the full distance. Real race times typically slow 5-8% over longer events, so treat marathon predictions as an upper-bound goal time.
Pace zones (easy, marathon, threshold, interval, sprint) help structure training. Easy runs build aerobic base, threshold runs raise lactate tolerance, intervals build VO2 max. Most weekly mileage should sit in the easy zone.
Yes. The math is identical — just enter your distance and time. Cyclists usually prefer speed (km/h or mph), which we display alongside pace. Walkers will fall in the lowest zone.
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