What this calculator does
A half marathon or full marathon is long enough that a small pacing mistake in the first few kilometres compounds badly by the finish, which is why runners plan a race around a target pace rather than just hoping to feel right on the day. A marathon pace calculator built for the distance also needs to show the checkpoints along the way, not just the average.
This half marathon pace calculator takes a target finish time for either distance and returns the pace needed per kilometre and per mile, along with a full table of split times at each 5 km checkpoint through to the finish, so the pace on race day can be checked against the clock at every marker.
The formula
Required pace is simply the target time divided by the race distance: pace = time / distance. Each checkpoint’s cumulative split time then follows by multiplying that pace by the distance covered so far, so a 5 km split is five times the per-kilometre pace, a 10 km split is ten times, and so on out to the full 21.0975 km or 42.195 km.
| Term | Meaning |
|---|---|
| Pace | Time required per kilometre or per mile, held constant across the whole race. |
| Split | The cumulative elapsed time expected at a given checkpoint, such as 10 km, if pace is held steady. |
| 21.0975 km / 42.195 km | The official half marathon and full marathon distances respectively. |
The inputs explained
| Field | What to enter |
|---|---|
| Race distance | Choose half marathon (21.0975 km) or full marathon (42.195 km). |
| Target time: hours | Hours component of the target finish time. |
| Target time: minutes | Minutes component of the target finish time. |
| Target time: seconds | Seconds component of the target finish time. |
When to use it
Planning even splits for race day
A runner targeting a specific half marathon or full marathon finish time uses the pace and split table here to check their watch against the plan at each 5 km marker, catching an early pace mistake before it costs the whole race.
Comparing a half marathon pace chart km by km
A half marathon pace chart km target, such as 4:45 per km for a sub-1:40 finish, is exactly what the required pace figure here shows, alongside the per-mile equivalent for courses or watches marked in miles.
Working out a marathon calculator target from a recent race
A runner who knows their recent half marathon time and wants to see what pace a first full marathon would need can switch the race distance selector and re-run the same target time for a rough comparison.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
Half marathon pace and splits across a range of target times
A range of half marathon target finish times, from an ambitious 1:30 to a steady 2:30.
| Target time | Required pace | Pace per mile |
|---|---|---|
| 1:30 | 4:16 min/km | 6:52 min/mile |
| 1:45 | 4:59 min/km | 8:01 min/mile |
| 2:00 | 5:41 min/km | 9:09 min/mile |
| 2:15 | 6:24 min/km | 10:18 min/mile |
| 2:30 | 7:07 min/km | 11:27 min/mile |
Full marathon pace and splits across a range of target times
A range of full marathon target finish times, from a fast club-level 3:00 to a comfortable 5:00.
| Target time (hours) | Required pace | Target finish time |
|---|---|---|
| 3:00 | 4:16 min/km | 3:00:00 |
| 3:30 | 4:59 min/km | 3:30:00 |
| 4:00 | 5:41 min/km | 4:00:00 |
| 4:30 | 6:24 min/km | 4:30:00 |
| 5:00 | 7:07 min/km | 5:00:00 |
Questions
How do I work out my half marathon pace?
Divide the target finish time by the half marathon distance, 21.0975 km. This calculator does that division directly and also shows the equivalent pace per mile and the split time expected at each 5 km checkpoint.
What pace do I need for a 2 hour half marathon?
A 2:00:00 half marathon needs a pace of about 5:41 per km, or roughly 9:09 per mile, held evenly from start to finish across the full 21.0975 km.
Is this the same as a full marathon pace calculator?
It covers both. Selecting full marathon switches the target distance to 42.195 km and the checkpoint table to 5 km splits out to 40 km plus the finish, rather than the half marathon’s shorter set of checkpoints.
Why do splits matter more than just an average pace?
An even pace across the whole race is usually the fastest strategy, since starting too quickly builds up fatigue that costs more time late in the race than it gains early on. Checking splits at each marker catches that mistake while there is still time to correct it.
For pace, speed or finish time on any distance, not just a half or full marathon, see the general pace calculator. For converting between running pace and speed on a single run, see the running pace and finish time calculator.