Beginner Marathon Pace: How to Pace Your First 26.2 Miles
Pick a target your race results actually support, know your checkpoint times by heart, and understand exactly what a fast start costs. All numbers computed, not estimated.
The marathon is the only common race distance where pacing errors are usually unrecoverable. Go out ten seconds per km too fast in a 10K and you lose a minute; do it in a marathon and you can lose twenty. This guide gives a beginner three things: a target pace chosen from evidence rather than ambition, the checkpoint times that tell you mid-race whether you are on plan, and the actual arithmetic of what going out too fast costs — which is not what most advice says it is.
Step 1: pick a target your races support
Race predictions use the Riegel formula, which scales a known race time up to a longer distance. Read this table backwards: find the row whose half marathon, 10K or 5K time you have already run, and that is the marathon target your fitness supports.
| Marathon target | Half marathon | 10K | 5K / parkrun |
|---|---|---|---|
| 4:00 | 1:55:07 | 52:10 | 25:01 |
| 4:15 | 2:02:18 | 55:26 | 26:35 |
| 4:30 | 2:09:30 | 58:42 | 28:09 |
| 5:00 | 2:23:53 | 1:05:13 | 31:17 |
| 5:30 | 2:38:17 | 1:11:44 | 34:24 |
Two honest caveats. First, Riegel assumes you have trained for the distance you are predicting — it describes what your speed is worth with a proper long-run base. For a first marathon, treat the prediction as a best case and add 10–15 minutes. Second, this is why the old club rule — "double your half and add 10 to 15 minutes" — works: a 1:55 half predicts 3:59:46 by Riegel, and the folk rule gives 4:00–4:05. The rule of thumb is just Riegel with the first-timer margin already built in.
Step 2: learn your checkpoint times
Even pacing turns the marathon from one enormous question into four small ones. These are the splits for a perfectly even race:
| Target | Per km | Per mile | 10K | Halfway | 30K | 20 miles |
|---|---|---|---|---|---|---|
| 4:00 | 5:41 | 9:09 | 56:53 | 2:00:00 | 2:50:38 | 3:03:05 |
| 4:15 | 6:03 | 9:44 | 1:00:26 | 2:07:30 | 3:01:18 | 3:14:31 |
| 4:30 | 6:24 | 10:18 | 1:03:59 | 2:15:00 | 3:11:58 | 3:25:58 |
| 5:00 | 7:07 | 11:27 | 1:11:06 | 2:30:00 | 3:33:18 | 3:48:51 |
| 5:30 | 7:49 | 12:35 | 1:18:12 | 2:45:00 | 3:54:37 | 4:11:44 |
The 20-mile checkpoint deserves special attention, because 20 miles is 32.19 km — which leaves 10.01 km to run. A marathon is a 20-mile run followed by a 10K, almost to the metre. Memorise your 20-mile time and your everyday 10K-when-tired time, and the final stretch becomes a distance you have covered dozens of times rather than uncharted territory.
The "time in the bank" myth, done properly
Most pacing advice tells you banking time does not work but not why, so here is the actual arithmetic. Suppose you target 4:30 and go through halfway three minutes early. Spread over the remaining 21.0975 km, that buffer lets you slow by 8.5 seconds per km and still finish on target. The maths does not punish a fast start at all — it rewards it.
The punishment is physiological. Running faster than trained pace burns glycogen disproportionately, and the bill arrives around 30K as a fade far larger than anything you banked. Say you cover the first half at 4:15 pace while targeting 4:30 — only 21 seconds per km too fast, easily done in the excitement of a race start. You arrive at halfway 7:30 ahead. Here is what fades from 30K cost against that:
| Fade from 30K | Time lost | Net result of the "banked" 7:30 |
|---|---|---|
| 10 s/km slower | +2:02 | still ahead — if you get away with it |
| 30 s/km slower | +6:06 | most of the bank gone |
| 60 s/km slower (walk-run) | +12:12 | 4:42 finish — and a miserable last hour |
The trade is asymmetric: the upside of banking is capped at what you banked, and the downside is not capped at all. A minute-per-km fade over the last 12 km is not a worst case, it is the standard outcome of a 20-second-per-km-fast first half in a first marathon. How large your fade would be is unknowable in advance — which is exactly why the bet is bad.
Build in a cheap buffer instead
If you want margin, take it the boring way: pace the whole race a touch quick rather than the first half very quick. One second per km is worth 42 seconds over the marathon; three seconds per km is worth 2:07. Planning a 4:30 attempt around 6:21/km (finishing 4:27:56) instead of 6:24 gives you over two minutes of protection for a pace difference you can barely feel — and unlike banked time, it is spread across the race instead of loaded onto your legs in the first hour.
A worked plan for a 4:30 marathon
- km 1–10 at 6:30/km — deliberately 6 s/km conservative while the crowd sorts itself out. Through 10K at 1:05:00, about a minute behind even pace. That minute is insurance, not lost time.
- km 11–30 at 6:20/km — settle into just-under-target rhythm. Arrive at 30K at 3:11:40, back on even pace without ever surging.
- km 31–finish at 6:24/km — hold target pace as deep as you can. This plan crosses the line at 4:29:43 with even effort throughout.
- At 30K, check the table: 3:11:58 is even pace. Ahead and feeling controlled — hold. Behind — do not chase it back in one kilometre; 20 seconds recovered over 12 km is 1.7 s/km, barely a change.
Race-day tactics that survive contact with reality
- Watch average pace, not current pace. GPS instant pace swings 20–30 s/km with tree cover and tall buildings. Average lap pace is the number that means something.
- Run the tangents. The measured racing line is the shortest legal line; running wide on every bend adds 200–400 m, which at 4:30 pace costs 1:17 to 2:34. Your GPS reading 42.6 km at the finish is this, not a long course.
- Walk the aid stations. Fifteen slow seconds every 5 km costs about two minutes across the race and buys you fluid actually drunk rather than worn. Fuel from 45–60 minutes in, before you feel you need it — missed fuelling looks exactly like pacing failure from the inside.
- Seed yourself honestly. Starting with the 4:00 group when targeting 4:30 means being swept along 20 s/km fast during precisely the kilometres where it feels effortless — the table above shows how that ends.
Work out your own numbers
Use the pace calculator to convert any target time into per-km and per-mile pace, and the running pace chart for the full conversion tables. If your goal is the half instead, the sub-2 half marathon guide applies the same method there, and the negative split guide covers how to structure a finish once you have a race or two behind you.
Frequently asked questions
What is a good marathon pace for a beginner?
The one your recent race results support, not a round number. A 58:42 10K or a 2:09:30 half marathon supports a 4:30 marathon (6:24 per km); a 52:10 10K supports 4:00 (5:41 per km). Most first-timers finish between 4:15 and 5:30. Picking pace from evidence rather than ambition is the single biggest thing that decides how the last 10K feels.
How do I predict my marathon time from a half marathon?
Multiply your half marathon time by roughly 2.08 to 2.09 (the Riegel formula). A 1:55 half predicts about 3:59:46. But that assumes full marathon training; for a first marathon, add 10 to 15 minutes to the prediction. The old rule of thumb, double your half and add 10 to 15 minutes, lands in the same place, which is why it has survived.
Is it OK to bank time in the first half of a marathon?
The arithmetic says yes, the physiology says no. Going through halfway three minutes early means you could run the entire second half 8.5 seconds per km slower and still hit your target, so banking time makes the maths easier. The problem is that the fast first half burns glycogen faster, and the price is not paid in seconds per km, it is paid in a fade at 30K that is far bigger than what you banked.
What happens if I go out too fast in a marathon?
The cost arrives late and it compounds. On a 4:30 target, slowing by 30 seconds per km from 30K adds 6 minutes; slowing by a minute per km, a walk-run shuffle, adds over 12. Compare that with the 7:30 you banked by running the first half at 4:15 pace, and the trade is plainly bad. Almost every first marathon that goes wrong goes wrong this way.
Should I aim for even splits in my first marathon?
Even or very slightly conservative early. Start 5 to 10 seconds per km slower than target for the first 10K, settle into target pace through 30K, and spend whatever is left at the end. A three-second-per-km cushion across the whole race is worth 2 minutes 7 seconds, so building your plan around 4:29 rather than 4:30 gives you margin without changing how the race feels.
Method and assumptions
All splits and conversions are computed exactly (marathon 42.195 km, half 21.0975 km, 1 mile = 1.609344 km) rather than transcribed, and rounded to the second. Race equivalents use the Riegel formula with the customary exponent of 1.06; that exponent is a convention fitted to trained runners, not a physical law, and it flatters runners without a long-run base — hence the 10–15 minute first-marathon margin, which is a rule of thumb and labelled as such. The fade scenarios are illustrative arithmetic, not predictions: how much any individual slows after going out too fast is not computable in advance, which is the argument for not finding out. PaceCalc is published by CJ Software Ltd. Last reviewed August 2026.