Calculate percentages of race pace for workouts
This tool helps you calculate running paces for workouts that are designed to be done at specific percentages of race pace.
Let's say your workout is 4 x 1 mile at 90% of 5K pace. Enter your 5K pace (e.g. 5:30/mi) and the target percentage (90%), and the calculator will give you your workout pace (e.g. 6:03/mi). You can also convert your pace to per-mile, per-kilometer, 400m, and 200m splits.
Percentage-based workouts are used by coaches like Renato Canova and John Davis to help runners build speed and endurance at race-specific paces.
When coaches talk about running at "90% of race pace," there are actually two ways to do that math, and they give you slightly different paces.
The multiplication method thinks in terms of pace (time per mile): at 90%, you add 10% more time to your pace. If you race at 8:00/mi, that's 48 seconds slower — 8:48/mi. It's symmetric: 110% would be exactly 48 seconds faster.
The division method thinks in terms of actual speed — how much ground you cover per second. At 90%, you're moving 90% as fast, which slows your pace slightly more: 8:00/mi becomes 8:53/mi instead of 8:48/mi. The gap is small near race pace but grows as you go slower — over 30 seconds per mile at 70% pace.
You can adjust this setting by using the Percent of Pace / Percent of Speed toggle at the top of this page. I suggest using this calculator's default setting (Percent of Pace).
By default, paces are rounded to the nearest second and decimals are hidden. If you want better accuracy, you can use the Hide Decimal / Show Decimal toggle to display any pace conversion to the nearest tenth of a second. When outputting 400m and 200m paces, decimals are automatically displayed.
If your workout goes better than expected: let's say you ran 4 x 1 mile at 90% of 5K pace and had a great day, averaging 5:48/mi even though your plan was to run 6:03/mi based on a 5K pace of 5:30/mi. You can make the reverse calculation with the Forward/Backward toggle to figure out what original pace would've yielded 5:48/mi at 90%. In this example, it's 5:16/mi.
This calculator will remember your settings using browser storage. If you come back later, you'll be able to pick up where you left off. You can clear the storage and reset all settings to their defaults by clicking Restore Defaults.
