Pace, speed and finish time: three views of the same run
Runners usually think in pace: how long one kilometre or one mile takes. A 5:00 pace means five minutes per kilometre. Speed is the same information flipped over, in kilometres or miles per hour, and cyclists and treadmills often prefer it. Finish time is pace stretched across a whole distance. This calculator moves between all three: give it a distance and a time to get pace, a distance and a pace to get a finish time, or a time and a pace to get the distance you will cover.
Knowing your pace makes training and racing calmer. Easy days can stay genuinely easy, long runs can start sensibly, and a race goal becomes a series of small, checkable splits instead of a hopeful guess. It also makes treadmill sessions, where the belt shows speed, easy to translate into outdoor terms. Use the numbers as a guide, not a command: heat, hills, wind, trails and tired legs all change what a given pace costs. This page is for information and training planning only and is not medical advice.
How pace is calculated
All three modes use the same relationship, rearranged. Internally this page converts everything to seconds per kilometre, using 1 mile = 1.609344 km exactly, so a pace per mile is always a pace per kilometre multiplied by 1.609344. Times are displayed as M:SS under an hour and H:MM:SS over an hour.
How splits work
A split is your time for each unit of the course, usually each kilometre or mile, shown both on its own and cumulatively. Even splits mean holding the same pace throughout, the simplest plan and the one the table below assumes. A negative split, running the second half slightly faster than the first, is how most distance records are set and how many runners avoid the classic mistake of starting too fast and fading. Checking splits every kilometre is enough for most people; checking constantly turns a run into a maths lesson and often leads to surging.
Worked example
You run 10 km in 50 minutes 0 seconds. Pace = 3,000 seconds ÷ 10 = 300 seconds per kilometre = 5:00/km. Per mile that is 300 × 1.609344 = 482.8 seconds = 8:03/mi. At the same pace, a half marathon (21.0975 km) would take about 1:45:29 and a marathon about 3:30:59.
How to use this calculator
- Choose what to calculate: pace, finish time, or distance.
- For pace mode, enter distance, its unit, and your time in hours, minutes and seconds.
- For the other modes, also enter your pace and its unit.
- Read your pace per kilometre and per mile, plus your speed.
- Use the splits table and the race predictions for 5K, 10K, half marathon and marathon.
Using pace wisely in training and racing
Most of your running should feel easier than race pace. Easy and long runs build the aerobic base that makes faster paces possible, and they only work if they stay easy, which a pace or heart rate check can enforce on days when you feel tempted to push. Save goal pace for specific sessions and races, and remember that a predicted marathon time from a short, flat, cool run will flatter you if the marathon is hot or hilly.
Beginners should build distance gradually and stop for pain that changes how they move, chest symptoms or dizziness, and seek advice from a qualified professional about any health concern before starting a demanding programme. Experienced runners know the other lesson: the best pace plan is the one that leaves something for the final kilometres. Information only, not medical advice.
Important note
For information only — not medical advice. This calculator uses standard published formulas to estimate values for general education and planning. It does not diagnose, treat, or replace the advice of a doctor or other qualified health professional. If you have a health concern, are pregnant, or are making decisions about treatment, medication, or a major diet or exercise change, please talk to a healthcare professional first.