Sub-18 5K
A sub-18 5K means 5:48 per mile (3:36 per kilometre) — a 56.3 VDOT performance, run within a few seconds of your interval pace for the whole race. It is short, it is honest, and it is won on Tuesdays.
Mile-by-mile splits for 18:00
Five kilometres is short enough that pacing feels like a formality and long enough that it absolutely is not. The even-split table holds 5:48 per mile to 18:00, passing halfway at 9:00. Go through the first mile more than a few seconds under and the third mile stops being a race and becomes damage control.
The negative-split table opens at 5:51 per mile and closes at 5:44, hitting halfway at 9:05. In a 5K the margin is thin enough that this is less about fuel and more about nerve: it keeps the last kilometre under your control, which is exactly where a sub-18 is won or lost.
Even splits — 5:48 per mile
| Mile | Pace | Split | Elapsed |
|---|---|---|---|
| 1 | 5:48 | 5:48 | 5:48 |
| 2 | 5:48 | 5:48 | 11:35 |
| 3 | 5:48 | 5:48 | 17:23 |
| 3.1 | 5:48 | 0:37 | 18:00 |
Even pacing: 5:48 per mile for all 3.1 miles, finishing in 18:00.
Slight negative split — 5:51 out, 5:44 home
| Mile | Pace | Split | Elapsed |
|---|---|---|---|
| 1 | 5:51 | 5:51 | 5:51 |
| 2 | 5:48 | 5:48 | 11:39 |
| 3 | 5:44 | 5:44 | 17:23 |
| 3.1 | 5:44 | 0:37 | 18:00 |
One percent either side of even: 5:51 per mile through halfway (9:05), then 5:44 home. Same 18:00 finish. The mile that straddles halfway blends both paces.
Per kilometre — 3:36 per km
| Km | Pace | Split | Elapsed |
|---|---|---|---|
| 1 | 3:36 | 3:36 | 3:36 |
| 2 | 3:36 | 3:36 | 7:12 |
| 3 | 3:36 | 3:36 | 10:48 |
| 4 | 3:36 | 3:36 | 14:24 |
| 5 | 3:36 | 3:36 | 18:00 |
Even pacing in metric: 3:36 per kilometre across 5.0 km.
Are you ready for a sub-18 5K?
| Distance | Equivalent time | Pace /mi | Pace /km |
|---|---|---|---|
| 5K — your goal (18:00) | 18:00 | 5:48 | 3:36 |
| 10K | 37:20 | 6:01 | 3:44 |
| Half Marathon | 1:22:35 | 6:18 | 3:55 |
| Marathon | 2:52:28 | 6:35 | 4:05 |
Equivalent times are computed from the rounded VDOT of 56.3, so the 5K row lands within a few seconds of 18:00 rather than exactly on it. That is rounding, not a different prediction.
The entry fee reads as follows: it lines up with about a 37:20 10K and a 1:22:35 half marathon. A sub-18 5K does not require a big engine so much as a sharpened one — the aerobic base of those equivalent times, with a top end filed to a point.
The number to sit with is 5:48 against your threshold of 6:13: you will spend the entire race well above the pace your body can buffer, within a few seconds of your interval prescription of 5:45. That is why this barrier moves on track nights rather than Sunday mornings — 400s and 800s at 5:23 and 5:45, week over week, until the pace that currently reads as a red line starts to read as a rhythm. From there, 18:00 is one even-paced, slightly brave morning.
Eighteen minutes is the weeknight-5000 respectability line — the time that moves you from 'runs a bit' to a name people expect near the front of the second pack. It is 3:36 per kilometre, 5:48 per mile, raced within three seconds of your interval prescription of 5:45, and the sessions that produce it are the classical liturgy: 400s at 5:23, 1000s at 5:45, a tempo at 6:13 to keep the floor high. The equivalent half of 1:22:35 is a useful humility check in both directions — speed without that endurance stalls here, and endurance without this speed stalls exactly here too.
Where do you stand right now?
Enter a race you have actually run and this will tell you where you stand against the 56.3 VDOT a sub-18 5K requires — your score, the target, and the gap. Nothing is stored or sent anywhere.
Training paces for a sub-18 5K
These are day-one paces for a 56.3 VDOT — the fitness a sub-18 5K requires. They are a snapshot, not a season: as you get fitter every one of them should get faster, and training at last month's paces is how a good block goes stale.
| Pace | min/mi | min/km | Where it is used |
|---|---|---|---|
| Easy | 7:29 | 4:39 | Most of your week |
| Marathon | 6:35 | 4:05 | Race-pace work |
| Threshold | 6:13 | 3:52 | Tempo / cruise intervals |
| Interval | 5:45 | 3:34 | VO₂max work |
| Repetition | 5:23 | 3:21 | Speed and form |
| Recovery | 9:05 | 5:39 | Shake-out jogs |
Easy pace is a range rather than a point — Daniels defines it as 59–74% of VO₂max, which for the fitness behind a sub-18 5K runs from 7:09 to 8:35 per mile. The single easy figure below is the 70% value.
Paces that move when you do.
The table above is a static snapshot of the VDOT 56.3 behind a sub-18 5K. Why Not recalculates the same six paces after every run you log — pulling them tighter as you get fitter, easing them off when you are cooked, and rebuilding the plan around the weeks life actually gave you.
Build my sub-18 planSub-18 5K FAQ
5:48 per mile — exactly 3:36 per kilometre — with halfway at 9:00. Opening at 5:51 and closing at 5:44 lands the same 18:00 with the risk moved to the right end of the race.
VDOT 56.3, which sets every number on this page — the equivalents above and all six training paces below.
Track work, mostly: intervals at 5:45 and repetitions at 5:23, on top of a base kept honest by easy runs at 7:29. The race sits a few ticks off 5:45, so that is the pace to make familiar.
About a 37:20 10K or a 1:22:35 half — the VDOT 56.3 equivalents. A strong 10K with a stuck 5K is the classic sign the speed work is overdue.
Even, then brave: 3:36 per kilometre through 9:00 at halfway, and the final kilometre is where the race is allowed to cost. A fast first 800 at this level is a bill, not a deposit.
Every number on this page is computed from our own implementation of the Daniels–Gilbert formulas published in Daniels' Running Formula (Jack Daniels & Jimmy Gilbert) — the same library the Why Not app runs. Nothing is transcribed from the book's tables, and this site is not affiliated with or endorsed by the authors. Equivalent times assume you train appropriately for the target distance; that caveat is Daniels' own.
A coach for the price of a coffee run.
A human marathon coach runs $100 to $300 a month and rebuilds your plan when you email them. Why Not runs the same Daniels VDOT engine behind every number on this page and adapts after every workout. A full year of the app costs less than the cheapest month of human coaching.
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