How it works
5K pace = mile + 33 s; 10K ×1.15; 10 mi ×1.175; half ×1.2; marathon ×1.3
Galloway developed these factors over decades of coaching: from your one-mile time trial, each race pace per mile is the mile time adjusted by a fixed amount. The 5K pace adds 33 seconds; the 10K is 1.15 times the mile; ten miles is 1.175; the half marathon is 1.2; and the marathon is 1.3. Multiply each pace by the race distance in miles to get the predicted finish — for example, a 7:00 magic mile gives a 5K pace of 7:33 per mile (about 23:27) and a marathon pace of 9:06 per mile (about 3:58). The longer the race, the larger the slowdown factor, reflecting how endurance fades over distance. Because the test is short and repeatable, it is a practical way to gauge fitness and set realistic goal paces.
Sources
- Galloway Magic Mile Jeff Galloway, “Magic Mile” (jeffgalloway.com) — race-prediction factors from a one-mile time trial: 5K = mile + 33 s, 10K ×1.15, 10 mi ×1.175, half ×1.2, marathon ×1.3.
- Field-test prediction Short time-trial tests estimate race potential from current speed; Galloway’s factors are empirical, fitted across hundreds of thousands of runners.
- Endurance fade with distance Race pace slows predictably as distance grows — the basis for the increasing multipliers from 5K to the marathon.
FAQ
What is the Magic Mile?
A one-mile time trial, run at a hard but controlled effort, that Jeff Galloway uses to predict race times. After a warm-up you run a single fast mile, then apply Galloway’s factors to estimate your 5K through marathon paces. It is quick, repeatable, and needs only a measured mile.
How do I run a Magic Mile?
Warm up with easy jogging and a few strides, then run one mile as fast as you can sustain evenly — hard but not an all-out sprint that fades. Use a track or an accurately measured flat stretch. Note the time and enter it here; re-test every two to three weeks to see progress.
How accurate are the predictions?
They are realistic targets for a runner with appropriate endurance training, but the longer races assume you have done the mileage to back them up. The marathon prediction in particular is only reachable with solid long-run preparation; treat it as a goal to train toward, not a guarantee.
Why does the marathon use a bigger multiplier?
Because pace slows more over longer distances. A mile is run far faster than marathon pace, so the marathon factor (1.3) is larger than the 5K adjustment. The increasing multipliers capture how much you must ease off as the distance grows.
How often should I test?
Every two to three weeks is typical. Frequent testing tracks your fitness trend and keeps your goal paces current as training progresses. Always run the test under similar conditions — same course, similar weather — so the comparison is fair.
How does this differ from VDOT or Riegel predictions?
The Magic Mile uses Galloway’s fixed empirical factors from a single mile, while VDOT and Riegel are physiology- and power-law-based models usually fed by a longer race. They often land close; comparing them is a good sanity check on your goal.
Magic Mile predictions use Jeff Galloway’s empirical factors and are estimates, not guarantees. Longer-distance projections assume adequate endurance training. General information for training, not medical or coaching advice.