Weekly Running Mileage Safe Cap Calculator
Find next week’s safe mileage ceiling from your current volume using the 10% progression rule.
How it works
Next-week cap = current × (1 + rate) · rate default 10% · every 4th week, cut back ~20–30% to recover
The 10% rule is a widely taught guideline: raising weekly running volume by more than about 10% at a time is associated with more overuse injuries. Compounding that increase week over week grows mileage surprisingly fast, so a projection helps you set realistic goals. It is a rule of thumb, not a guarantee — cut back or hold steady if you feel niggles, and schedule a lighter "down" week roughly every fourth week.
Worked example
Running 20 miles this week, the standard 10% rule caps next week at 20 × 1.10 = 22 miles. Repeating that for four weeks reaches about 29.3 miles — a jump you should interrupt with a recovery week.
Frequently asked questions
Is the 10% rule proven?
It is a practical guideline rather than an ironclad law. Studies are mixed, but sudden large spikes in training load clearly raise injury risk, so keeping increases modest and gradual is sound advice for most runners.
Should I increase every single week?
No. Build for about three weeks, then take a down week at 20–30% lower volume to absorb the training. Continuous increases without recovery weeks are a common path to overtraining.
What if I am returning from a break?
Start well below your old peak and rebuild gradually. Fitness returns faster than tendons and bones adapt, so the first few weeks back are exactly when conservative increases matter most.
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Educational estimate only, not medical advice. Individual physiology varies — consult a qualified professional before changing your training or health routine.