How to Use the Running 10% Rule Calculator
Many running injuries happen because mileage increases too quickly. The widely cited 10% rule in sports medicine says you shouldn't raise your weekly running distance by more than 10% over the previous week, giving your bones, tendons, and muscles time to adapt to the new load. Enter this week's mileage and how many weeks you're planning to get a week-by-week target mileage table built on this principle.
This calculator increases mileage 10% each week, but automatically inserts a recovery week that cuts mileage by about 25% every 4th week. Continuous increases build up cumulative fatigue, so periodically lowering the load lets you keep progressing safely and consistently over the long run.
These numbers are a guideline, not a mandate. If you feel pain or severe fatigue, don't force the planned mileage — hold steady or scale back that week, then try again once you've recovered. That approach keeps you running injury-free for the long haul.
Frequently Asked Questions
Increasing weekly mileage by more than 10% at once doesn't give your bones, tendons, and muscles enough time to adapt, raising the risk of overuse injuries like stress fractures and runner's knee. Staying within 10% per week lets your body adapt safely.
No. After about 3-4 weeks of increases, it's best to include a recovery week where mileage drops 20-30%. This calculator automatically inserts a recovery week every 4th week.
Listen to your body over the numbers. If you feel pain or excessive fatigue, don't force the planned distance — maintain or reduce your mileage that week and try again once you've recovered.