How do I convert pace per mile to pace per kilometre?

Divide the seconds by 1.609. An 8:00 mile is 480 seconds, which becomes 298 seconds per kilometre, so 4:58. Going the other way, multiply by 1.609. Or skip the arithmetic and flip the units toggle in the calculator.

What pace do I need for a 4-hour marathon?

9:09 per mile or 5:41 per kilometre, held for the full 26.2. Because you will almost certainly cover a little more than the certified distance, aim for about 9:04 on your watch to cross the line safely under 4:00.

Why does my watch pace disagree with the official race pace?

Courses are measured along the shortest line a runner could legally take, and nobody runs that line. Weaving and wide corners mean your GPS reads long, typically 26.4 miles or more at a big marathon, so your watch pace reads faster than your official pace.

Running Pace Calculator

Work out the pace you need to hit a goal time, or the finish time a pace will give you, for any distance in miles or kilometres.

Race distance

Units

Finish time

min

sec

Pace / mi

8:03

Finish time

50:00

Speed

7.5 mph

How pace, time, and distance fit together

Pace is time divided by distance, and every question this calculator answers is that one equation rearranged. Know your goal time and the distance, and it hands you the pace to hold. Know the pace you can sustain, and it hands you the finish time. Speed is the same information flipped over: an 8:00 mile is 7.5 mph, a 5:00 kilometre is 12 km/h.

The units trip people up far more often than the maths. A kilometre is 0.621 miles, so a per-kilometre pace always looks quicker than the per-mile pace for the same run. To convert, divide your per-mile pace by 1.609. An 8:00 mile is a 4:58 kilometre. The toggle above does this exactly, which beats doing it in your head at mile 19.

A worked example

Say you want a 1:45 half marathon. That is 105 minutes spread over 13.11 miles, which works out to 8:01 per mile, or 4:59 per kilometre. Now run it the other way: training has shown you that 8:00 miles feel sustainable, so switch to pace-to-time mode and the calculator shows 8:00 pace brings you home in 1:44:51. The difference between those two plans is one second per mile. That is the level of precision worth planning with, because the fitness underneath it is far blurrier than the arithmetic.

The mistake that ruins race-day pace plans

Certified courses are measured along the shortest possible line, and nobody runs that line. Between weaving around other runners and swinging wide on corners, a GPS watch typically records 26.4 to 26.6 miles at a big city marathon, not 26.22. That extra distance means the pace on your wrist has to be a few seconds per mile faster than the official pace for your goal. For a 4:00 marathon the official pace is 9:09 per mile, but if you actually cover 26.45 miles you need your watch to average about 9:04.

Decide how you will handle that gap before the gun, not at mile 24. My own rule is to set the watch target five seconds per mile faster than the official goal pace and treat anything the official chart says as the celebration number, not the plan.

Once you have your pace, the race pace predictor prints a band with every split, and the marathon pace chart lists the splits for every goal from 2:30 to 6:00. New to pacing? Start with the beginner's guide to pace and splits.

Pace calculator questions

How do I convert pace per mile to pace per kilometre?: Divide the seconds by 1.609. An 8:00 mile is 480 seconds, which becomes 298 seconds per kilometre, so 4:58. Going the other way, multiply by 1.609. Or skip the arithmetic and flip the units toggle in the calculator.
What pace do I need for a 4-hour marathon?: 9:09 per mile or 5:41 per kilometre, held for the full 26.2. Because you will almost certainly cover a little more than the certified distance, aim for about 9:04 on your watch to cross the line safely under 4:00.
Why does my watch pace disagree with the official race pace?: Courses are measured along the shortest line a runner could legally take, and nobody runs that line. Weaving and wide corners mean your GPS reads long, typically 26.4 miles or more at a big marathon, so your watch pace reads faster than your official pace.