Pace versus speed
Pace and speed describe the same movement from opposite ends. Pace is the time you take to cover a fixed distance, such as minutes per kilometer or per mile, so a smaller number is faster. Speed is the distance you cover in a fixed time, such as kilometers per hour, so a bigger number is faster. Runners usually think in pace and cyclists in speed, which is why a converter is useful. They are linked by a single division. A pace of 5:00 /km means 5 minutes for every kilometer, so in an hour you cover 12 km and the speed is 12.00 km/h. In miles the same pace is 8:02.8 /mile, because a mile is 1.609344 times as long as a kilometer. The pace calculator below handles eight units: pace per kilometer and per mile, kilometers per hour, miles per hour, meters per minute, meters per second, yards per minute and yards per second.
Solve your missing value
Pace, time and distance are three sides of one relationship: time = distance × pace. Give the calculator any two and it finds the third. Choose "Pace" to learn how fast you ran, with a distance and a time. Choose "Time" with a distance and a pace to see how long a run would take. Choose "Distance" with a time and a pace to see how far you would get. The default example is 25:00 for 5 km, which gives 5:00 /km. A 10 km run at a steady 12 km/h takes 50:00, because 10 ÷ 12 of an hour is 50 minutes. Times use separate boxes for hours, minutes and seconds, and you can leave the unused ones blank. The calculation keeps full precision and rounds the displayed result only once, to the nearest tenth of a second.
A few habits keep the answer reliable. Start with the quantity you care about, then fill only the fields the page asks for. If a result looks surprising, check the units first, because a distance typed in miles but read as kilometers is the usual cause. The rounding to a tenth of a second is for display only.
5K, half marathon and marathon examples
The same pace can be applied to any distance. At 5:00 /km, the table of equivalent distances shows a 5K in 25:00, a 10K in 50:00, a half marathon in 1:45:29.3 and a full marathon in 3:30:58.5. The half marathon is entered as exactly 21.0975 km and the marathon as exactly 42.195 km, not as rounded values, so a marathon at 5:00 per kilometer is 42.195 × 300 seconds = 12,658.5 seconds, or 3:30:58.5. These are plain arithmetic. They do not say you could hold that pace for the longer distance. Races of different lengths demand different things, and the page makes no attempt to predict one result from another. Pick an event from the menu to fill in its distance, then solve for whichever value you need.
Working backwards is just as common. A goal of 22:30 for 5K needs 4:30 /km, which is 7:14.5 /mile. A target for a longer race is solved the same way, and the equivalent-distance table then shows what that pace means for the other distances. Pick the event from the menu and its exact distance is filled in for you.
Lap versus cumulative splits
Splits break a run into segments so you can see where you sped up or slowed down. There are two ways to record them, and mixing them up is the most common mistake. A cumulative marker is the total from the start. A lap is just one segment. If your watch shows 5:00 at 1 km, 10:30 at 2 km and 16:00 at 3 km, those are cumulative markers. The calculator subtracts the previous marker, so the segments are 1 km in 5:00, 1 km in 5:30 and 1 km in 5:30. If you instead enter 5:00, 5:30 and 5:30 in lap mode, you get exactly the same segments and the same totals.
The average pace is total time divided by total distance. Here that is 16:00 over 3 km, or 5:20 /km. It is not the plain mean of the segment paces, which is only the same when every segment has the same length. For example, 1 km in 5:00 followed by 4 km in 28:00 averages 6:36 /km, while the mean of 5:00 and 7:00 would wrongly give 6:00. You can enter up to twelve rows, with a different unit on each, and the page draws the segment paces as a bar chart with a table beside it. In cumulative mode, each marker must be larger than the one before in both distance and time, or the calculator tells you which row to fix.
Constant-pace finish projection
The finish-time tool answers one narrow question: if I hold the pace I have run so far, when will I finish? The formula is elapsed time × full distance ÷ distance covered. With 1 km done in 6:15 of a 5 km race, the projection is 6:15 × 5 ÷ 1 = 31:15, which leaves 25:00 to run. At the finish line the time remaining is zero, and a distance beyond the full distance is rejected. The projection assumes that pace never changes. Hills, heat, fatigue, a tailwind or a final sprint all break that assumption, so treat the result as the answer to a what-if, not as a forecast of your finishing time.
Used mid-race or in training, the same formula helps you decide whether to speed up or ease off. If the projected time is slower than your goal, you can put the goal into the solver to see the pace it needs, though the page does not do that subtraction for you.
Units, rounding and export limits
Distances accept kilometers, miles, meters and yards up to the equivalent of 1,000 km, with 1 mile defined as 1,609.344 m and 1 yard as 0.9144 m. A time of 5.30 is not 5 minutes 30 seconds, so the calculator keeps minutes and seconds in separate boxes and rejects minutes above 59 and seconds of 60 or more. Even-split tables are capped at 1,000 rows, and the last row is shortened when the distance is not a whole number of intervals: 5 km in miles gives 4 rows, the last one only 0.11 mile. The splits table can be downloaded as a CSV file that contains numbers and fixed labels only. Nothing you enter is stored or sent anywhere. For clock times between two moments, use the hours between times calculator; for gaps between calendar dates when planning training, use the date calculator. See also the other tools in the Fitness & Health hub.
Pace calculator questions
How is pace calculated?
Divide the time by the distance. A 25-minute 5 km run is 25 ÷ 5 = 5 minutes per kilometer. Multiply by 1.609344 for the pace per mile, which here is 8:02.8 /mile. Divide 60 by the pace in minutes to get kilometers per hour, which is 12 here.
Is 5.30 the same as 5:30?
No. 5:30 means 5 minutes and 30 seconds, which is 330 seconds. 5.30 would be 5.3 minutes, or 318 seconds. Enter minutes and seconds in their own boxes to avoid the mix-up.
What is the difference between cumulative and lap times?
A cumulative time is the total from the start up to a marker. A lap time is only the time for one segment. Choose the mode that matches what your watch or race results show.
How is the average pace of several segments calculated?
Add all the segment times, add all the segment distances and divide. This weights each segment by its length. It is not the simple average of the segment paces. For example, 1 km in 5:00 and 4 km in 28:00 averages 6:36 per km, not 6:00.
Does the finish estimate predict fatigue?
No. It assumes you hold the same pace to the end. It does not model fatigue, terrain, weather or a change in effort, so it is arithmetic and not a forecast. It simply extends the pace you have run so far.