How it works
5K pace = mile + 33 s; 10K ×1.15; 10 mi ×1.175; half ×1.2; marathon ×1.3
Step 1 — enter a fresh, evenly paced test mile. Step 2 — read the table as a menu of paces. An 8:15 magic mile projects a 27:20 5K at 8:48 per mile, a 58:57 10K at 9:29, ten miles in 1:36:56 at 9:42, a 2:09:47 half marathon at 9:54 and a 4:41:12 marathon at 10:44. Step 3 — hand the paces out to workouts. One common approach: use the 5K pace for short repeats (for example, 800 m intervals at 8:48 per mile), the 10K-to-10-mile band of 9:29–9:42 for sustained tempo segments, and keep long runs far slower. Galloway’s marathon-training guidance is to run long runs at least two minutes per mile slower than the magic-mile marathon projection — 12:44 per mile or slower for this runner — and to slow down further in the heat. Step 4 — choose the goal race. Pick the distance you have the most weeks to prepare for and treat its projection as a ceiling to train toward, not the plan itself; the longer the race, the more it depends on long runs a single mile cannot see. Step 5 — after each retest, rebuild the paces: a runner who improves from 9:40 to 9:10 over six weeks moves the half-marathon projection from 2:32:04 to 2:24:12 and the marathon from 5:29:29 to 5:12:26, and every workout pace above shifts with it.
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
Can the magic mile set my run-walk-run ratio?
It sets the pace the ratio is built around. Galloway matches run-walk-run ratios to the pace your magic mile predicts, so a runner projecting 12:00-per-mile marathon pace walks more often than one projecting 9:00. If you take walk breaks during the test itself, Galloway suggests adjusting them from your normal training ratio. To see how a run and walk interval blends into an average pace and finish time, use the run-walk-run planner.
Can I run the test on a treadmill?
You can, as long as you compare treadmill tests only with other treadmill tests. Belt calibration varies between machines, and with no air resistance the same speed tends to feel a little easier than on the road, so a treadmill mile can flatter you. Use the same machine and incline every time, or test outdoors on a measured mile when you want a road-equivalent number. Convert belt speed to pace beforehand so you know which setting your target needs.
Should a magic mile replace a tune-up race?
Not entirely. The test is ideal for setting paces early in a block and checking progress between races, because it costs far less recovery than racing. A tune-up race four to six weeks before a half or full marathon adds what a mile cannot: pacing practice over distance, race-morning logistics and a fueling rehearsal. Many runners use both — magic miles to steer training, one tune-up race to confirm the goal.
Is the test suitable if I am new to running or returning from a break?
Wait until you have a few weeks of consistent easy running behind you. A hard mile on unconditioned legs is when calves and Achilles tendons tend to complain, and the result would understate where your fitness is heading anyway. For a first attempt, run at a strong but controlled effort rather than all-out, then work toward a true time trial on later tests. If you have any heart or health concerns, check with a doctor before a maximal effort.
What does a slower retest mean?
Usually fatigue, conditions or pacing rather than lost fitness. Testing the day after a long run, on a warm or windy afternoon, or after a first quarter run far too fast can each cost several seconds. Rule those out and retest after a few easy days. If times keep drifting slower over several weeks while training feels harder, treat it as a sign to reduce the load rather than push harder.
Does the magic mile work for a trail or hilly race?
Only loosely. Galloway’s factors describe road racing on reasonable courses, so a hilly or technical trail race will run slower than the projection by an amount that depends on the climbing and footing. Use the road projection as an effort reference, then plan the course by feel or with hill-adjusted pacing instead of chasing the flat-road time.
The projections apply Galloway’s fixed coaching factors to a single mile; they describe what your current speed could support with matching endurance training, not what you will run. This page is general training information, not medical or coaching advice: the workout paces are examples rather than an individual program, and a maximal mile is a hard effort — get medical clearance first if you have any health concerns.