First Marathon Pace Guide

Pacing is where most first-time marathoners go wrong. The excitement of race day, the crowd, the taper — everything conspires to make the early miles feel deceptively easy. Going out too fast by even 10–15 seconds per kilometre in the first half virtually guarantees a painful second half. This guide shows you how to choose a realistic target pace and execute it.

How to set a realistic marathon target time

The most reliable method is to base your target on a recent race time. Common prediction formulas include:

• From a recent half marathon: double your half marathon time and add 10–15 minutes. If you ran a 1:55 half, a 4:00–4:05 marathon is reasonable for a first attempt.
• From a 10K: multiply your 10K time by 4.6–4.7. A 50-minute 10K suggests a 3:50–3:55 marathon.

For your first marathon, err on the conservative side — add another 5–10 minutes to whatever the formula suggests. You have no marathon-specific data yet, and the final 10km of a marathon is a different experience from anything in training.

Even splits vs negative splits

An even-split strategy means running every kilometre at exactly the same pace. A negative split means running the second half slightly faster than the first. Both are vastly superior to going out too fast (a positive split), which is the default outcome for most first-timers.

For a first marathon, aim for even splits or a very slight positive split — starting 5–10 seconds per km slower than target pace in the first 10km and settling into pace from 10–30km. This accounts for the fact that your legs will feel better early than late, and that crowds and excitement will tempt you to run faster than you should.

The importance of the first 10km

The first 10km of a marathon should feel almost embarrassingly easy. If you feel like you're working at mile 6, you're in serious trouble for miles 22–26. A common marathon mistake is running the first half at half-marathon effort — that will destroy your second half. Hold back deliberately and trust the process.

Miles 18–22: the wall

The notorious "wall" usually hits between miles 18 and 22. Glycogen stores are depleted, legs are heavy, and pace slows involuntarily. Proper pacing, consistent fuelling (gels or sports drink every 45–60 minutes), and adequate hydration all reduce the severity of the wall — but almost no first-time marathoner avoids it entirely. If you've paced well, you can push through it. If you've gone out too fast, it becomes a survival shuffle.

Race day pacing tactics

• Start in the right corral: seed yourself honestly. Starting too far back costs time; starting too far forward leads to running other people's pace early on.
• Use a GPS watch: glance at your average pace every km, not instant pace. Instant pace swings wildly — average pace is what matters.
• Ignore the crowds: the first few kilometres through town with cheering spectators feel nothing like marathon pace. Stick to your watch.
• Walk through aid stations: it's faster than spilling water over your face while trying to run. A 20-second walk every 5km won't cost you much time and makes fuelling far more effective.
• Run the tangents: follow the shortest legal line around corners. Over a full marathon, running the tangents can save 200–400m compared to running the outside of every bend.

Sample pacing plan for a 4:30 marathon

Target pace: 6:24 per km (10:18 per mile)

• km 1–10: 6:30–6:35/km (slightly conservative)
• km 11–30: 6:22–6:26/km (target pace)
• km 31–42: hold 6:24/km as long as possible; accept slight drift in the final 5km

If you reach km 30 feeling good, you can push slightly. If you reach km 30 struggling, focus on form and reaching the finish — don't panic and don't stop unless you must.

Calculate your target pace

Use the PaceCalc running pace calculator to convert a marathon target time to per-km or per-mile pace, or to predict a finish time from your training paces.

Also see our negative split strategy guide for how to structure the second half of your race.