Marathon & Race Pace Split Calculator
Calculate your per-kilometre and per-mile splits for any race distance at any target time. Plan even splits, negative splits, or custom strategies.
Race Pacing Strategy Guide
Even vs Negative Splits
Even splits: the same pace every kilometre from start to finish. Theoretically optimal on flat courses — any deviation means either too fast early (leading to a blow-up) or too slow early (leaving time on the table). Negative split: the second half is faster than the first. Research shows negative-split marathons produce faster finishing times on average — the body has fully warmed up and glycogen is managed more efficiently. Most world records and personal bests are run on negative or even spli
The Marathon Wall
The marathon wall (hitting the wall / bonking) typically occurs at miles 18-22 when muscle glycogen runs critically low. The body switches from glucose to fat as the primary fuel — a less efficient process that dramatically reduces pace. Prevention: run the first half at conservative pace (even feeling artificially slow). Take on carbohydrate from kilometres 5-10 onwards (every 5km). Use caffeine gels in the second half — caffeine promotes fat oxidation and delays glycogen depletion. Well-traine
Race-in-Thirds Strategy
Popular for inexperienced marathon runners: First third: at least 10-15 seconds per km slower than goal pace. Second third: settle into goal pace. Final third: if feeling good, accelerate. This works because most runners who struggle in marathons went too fast in the opening miles when adrenaline and fresh legs make target pace feel effortlessly easy. Running the first 10K 30 seconds per km slower than goal pace loses only 5 minutes — but it may prevent losing 15-30 minutes in a blow-up between
5K and 10K Pacing
5K: even splits are most efficient — the race is short enough that glycogen is not the limiting factor. Go out at goal pace within the first 200m. Common mistake: sprinting the first 800m and dying. 10K: slight negative split works well — warm up efficiently in the first 3km, hold goal pace 3-9km, finish hard. The last kilometre of a 10K should be the fastest. Course strategy: conserve on uphills (relative to flat-equivalent effort), accelerate on downhills. Wind: run slightly harder into headwi
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