Free running calculators
Yasso 800 Calculator
The Yasso 800 is the classic marathon workout: ten 800 m repeats at a time that matches your marathon goal. Enter a goal to get your repeat time, or enter your 800s to see the marathon they point to.
How Yasso 800s work
Bart Yasso, who spent decades at Runner's World as its "Chief Running Officer", noticed that the time he could run ten 800 m repeats, in minutes and seconds, matched his marathon time in hours and minutes. If you can run 10 × 800 m in 3:30 each, with a 3:30 jog between them, you're in shape to run a 3:30 marathon.
800 m time (m:ss) = marathon time (h:mm)
There's no physiology behind the match; it's a coincidence of units that happens to line up for a lot of runners. It works as a check because the session is hard to fake: holding a steady pace for ten repeats takes the same aerobic strength a marathon does.
Yasso 800 times for common goals
| Marathon goal | Each 800 m | Per 400 m lap |
|---|---|---|
| 2:45:00 | 2:45 | 1:23 |
| 3:00:00 | 3:00 | 1:30 |
| 3:15:00 | 3:15 | 1:38 |
| 3:30:00 | 3:30 | 1:45 |
| 3:45:00 | 3:45 | 1:53 |
| 4:00:00 | 4:00 | 2:00 |
| 4:15:00 | 4:15 | 2:08 |
| 4:30:00 | 4:30 | 2:15 |
| 4:45:00 | 4:45 | 2:23 |
| 5:00:00 | 5:00 | 2:30 |
Running the workout
- Start small. Begin with four repeats about nine weeks before the race and add one a week until you reach ten.
- Jog the recovery. Recover with a slow jog for the same time as each repeat: 3:30 repeats get 3:30 jogs.
- Hold every repeat. The goal is ten even repeats, not one fast one. If the last two slow down, you've found your current level.
- Finish early. Run your last ten-repeat session at least ten days before the race so you arrive rested.
How reliable is it?
Yasso 800s are a workout, not a race prediction. Running 800 m repeats in 3:30 shows good speed, but a 3:30 marathon also needs months of long runs and steady mileage. Many runners hit their Yasso times and still finish slower, usually because their long runs or weekly mileage fell short.
Use it together with a race-based estimate. The race time predictor turns a recent half marathon into a marathon estimate. When the two agree, you can trust the goal; when they don't, plan around the race-based one.
Frequently asked questions
What pace should Yasso 800s be?
The same number as your marathon goal, read as minutes and seconds. For a 4:00 marathon, each 800 m takes 4:00, or 2:00 per 400 m lap.
Can I run Yasso 800s on a treadmill?
Yes. Set the speed for your 800 m pace and use a 1% incline. The treadmill pace calculator will convert it.