Worked examples
Real numbers, real scores.
“run a marathon in 16 weeks”
40%
Bold, But Sane
- Distance to add
- 32.2 km
- Weekly long-run growth
- 8.6%
- Peak weekly volume
- ~63 km
“run a half marathon in 3 months”
41%
Optimism Detected
- Distance to add
- 13.1 km
- Weekly long-run growth
- 7.7%
- Peak weekly volume
- ~32 km
“run my first 5K in 6 weeks”
58%
Optimism Detected
- Distance to add
- 3.0 km
- Weekly long-run growth
- 15.1%
- Peak weekly volume
- ~8 km
How it’s scored
Math, not vibes.
Every factor is scored on its own, capped, and added up to a score from 0 to 100. Same inputs, same score, every time. It measures how hard the plan leans on optimism, not your odds of success.
Full methodologyLong-run build rate
Compound weekly growth your longest run needs × 2 — the common 10%-a-week rule of thumb scores 20.
max 40
Volume gap
Share of peak weekly volume (≈1.5× the target distance) you still need to add × 24.
max 24
Timeline compression
(6 − months) × 4.
max 20
Training frequency
(4 − runs per week) × 5.
max 16
Questions
Before you commit.
How long does it take to train for a marathon?
Many beginner plans run 16 to 20 weeks from a base of regular shorter runs. The calculator shows how many weeks your long run would take to reach race distance growing about 10% a week, from where you are today.
What is the 10% rule?
A common rule of thumb: increase your long run or weekly distance by no more than about 10% a week. It's guidance, not a law, but builds much faster than that are a classic route to injury.
Is this medical advice?
No. It is simple training math. Check with a doctor before a big jump in training, especially if you are new to running.