Negative splits

Pacing a negative split from your wrist? The Garmin Forerunner 165 shows a target pace for every split with PacePro, so you can see each split against the plan as you run. See the picks and sources. As an Amazon Associate, Race Pace Planner earns from qualifying purchases. This is an affiliate link, at no extra cost to you. Affiliate disclosure.

By Rai Ansar · Updated 22 October 2026 · Tables generated by this site's calculator and verified by independent automated calculation checks. How pages are made

How big is a “gentle” negative split at each distance?

With the same 2% preset, here is what each half looks like. The gap is always about 1% of the goal time, so you run the second half about 2% faster than the first.

The top pages quote examples from 0.6% to 4.3% and none gives a sourced rule, because there is no agreed figure. Use the table as a scale, not a target.

Do negative splits work?

A 2025 mini review by Grivas in Frontiers in Physiology says that “a majority of record-breaking performances follow either an even or slight negative split profile”, that “recreational athletes tend to exhibit positive splits”, and that negative splits are “not universally applicable”. The proposed reasons are physiological: starting conservatively reduces “the risk of early glycogen depletion and excessive accumulation of lactate”. It is a review of earlier studies, not a new experiment.

The review gives two more reasons. A slower start produces less heat early, which helps when the last kilometres are the hottest part of the race, and it limits cardiovascular drift, the slow rise in heart rate at a steady pace that comes with dehydration and a rising core temperature. It also lists where a strict negative split stops making sense: hilly courses, high temperatures and crowded starts.

At the 2012 Honolulu Marathon, Wilson Kipsang went through halfway in 1:07:07 in a lead pack of eight, ran the second half in 1:05:24 and won in 2:12:31, according to the World Athletics race report. His second half was 1:43 quicker, 2.6% of his first-half time, a bigger swing than this site's 2% preset.

How to train for a negative split

You learn a negative split by running it in training, so the faster finish feels familiar on race day. These sessions come from the Grivas review and from D3 Multisport's coaching guide; race pace for a 3:30:00 marathon, as an example, is 4:59 per km (8:01 per mile).

• Progression long run. Start at an easy pace and build to race pace or faster over the final kilometres. The review calls it an effective way to rehearse the switch from a conservative start to a strong finish.
• Out-and-back tempo run. On a flat or rolling course, after a 10 to 15 minute warm-up, run out a little slower than race pace and come back a little faster, so the second half is the quicker one.
• Descending repeats. D3's example is 6 to 8 × 800 m (or 3 to 5 × 1 mile) where each repeat is quicker than the last: 4:10, 4:08, 4:06, 4:04, 4:02, 4:00 for a runner whose 800s are 4:00, with each 800 itself split 2:02 then 1:58.
• Pace awareness. Run by GPS, heart rate or perceived effort often enough to know what race pace feels like. The review says this lowers the chance of starting too fast.

On race day, the review adds course knowledge, a plan for heat and a fuelling plan. A printable pace band with negative-split checkpoints keeps the first half honest when the crowd goes out fast.

Negative splits in swimming, rowing and other sports

The definition does not change with the sport: the second half of the race is faster than the first. Wikipedia lists swimming, cycling, triathlon and horse racing, and gives Janet Evans's 400 m freestyle gold at the 1988 Olympics as a swimming example. For the pool, D3 Multisport suggests a 1,000-yard time trial in which the second 500 is faster than the first.

On a rowing machine, pace is time per 500 m. Concept2's 2K training plan lists two pacing strategies: a constant pace, or negative splits, which it describes as starting one or two seconds per 500 m slower than your target and finishing faster than the target average. With this site's 2% preset, an 8:00 2K (2:00 per 500 m) becomes 4:02 for the first 1,000 m and 3:58 for the second, about 2:01 and 1:59 per 500 m. Concept2 also notes that many 2K race plans open with a sprint start, so a rowing race is not always split that way.

The common mistake: banking or losing too much early

Every second you fall behind even pace by halfway has to be made up in the second half. If you run the first 21.0975 km of a marathon 10 seconds per km slower than even pace, you are 3:31 behind. To still finish on time, the second half must be 10 seconds per km faster than even pace: a 20-second-per-km swing between halves. In a 10K, running the first 5 km 5 seconds per km slower than even pace leaves you 25 seconds to make up. Hills and heat change the picture, and none of this is modelled here.

Even splits, and why constant pace is not constant effort

Even splits hold one pace from start to finish. On a flat course in steady weather that is close to even effort; on hills or into the wind it is not, which is why course-aware bands exist. Whole seconds also matter: a 49:35 10K is 297.5 seconds per km, so the kilometres alternate between 4:58 and 4:57 and each checkpoint stays within half a second of the exact time.

Plan your own negative split

Enter your race and goal. The calculator starts on negative splits and shows even and positive alongside; the printed band uses whichever you pick. Average pace for the whole race stays 4:59 per km at 3:30:00 (8:01 per mile) whichever shape you choose.

Negative split FAQ