The half marathon is the distance most runners think they have figured out — until they line up for it and discover that 13.1 miles at "comfortable hard" pace is a very different beast from 6.2 miles at the same effort. The pacing strategy that consistently produces personal records is not even pacing. It's a controlled negative split: run the second half faster than the first.

Why even pacing fails most amateur runners

The instinct on race morning, fueled by adrenaline and fresh legs, is to bank time early. The problem: glycogen depletion and accumulating fatigue mean the back half costs more than the front. Bank 30 seconds at mile 4, lose 90 seconds between miles 10 and 13. Net: you finished slower and felt worse than you would have at a controlled pace.

The negative-split strategy

Aim to run the second 10K faster than the first 10K by 30–60 seconds. The breakdown for a goal time T:

  • Miles 1–3: 8–12 seconds/mile slower than goal pace. Settle in. Resist the urge to chase.
  • Miles 4–8: goal pace. Lock in.
  • Miles 9–11: 3–5 seconds/mile faster than goal pace. Pick up.
  • Miles 12–13.1: as fast as you can sustain. This is where the time gets won.

Worked example: sub-2:00 half marathon

Goal: 1:59:59 over 13.1 miles → goal pace 9:09/mile

  • Miles 1–3: 9:18–9:21/mile (banking negative 30 seconds — the opposite of what most runners do)
  • Miles 4–8: 9:09/mile
  • Miles 9–11: 9:04–9:06/mile
  • Miles 12–13.1: under 9:00/mile if possible

That gives a 1st-half/2nd-half split of approximately 60:00 / 59:59 — a clean even split with a strong finish, which actually feels better than even pacing because the slow first miles preserve energy for when you need it.

Goal pace by goal time

  • 1:30: 6:52/mile
  • 1:40: 7:38/mile
  • 1:45: 8:01/mile
  • 1:50: 8:24/mile
  • 2:00: 9:09/mile
  • 2:15: 10:18/mile
  • 2:30: 11:27/mile

Race-day mistakes that ruin pacing

  1. Starting too close to the front. If you line up with faster runners you'll get pulled along at their pace.
  2. Watching everyone else. Their goal isn't yours. Run your own race.
  3. Skipping water stops. Even mild dehydration costs 10+ seconds per mile in the second half.
  4. Trying new gels on race day. Train with what you'll race with.
  5. Overstriding on hills. Maintain effort, not pace, on uphills. Let the downhills give the time back.

Fueling and hydration plan

For a 2-hour half marathon:

  • Pre-race: 16 oz water 90 min before, 8 oz 20 min before, normal carb breakfast 2.5–3 hours before
  • During: 1 gel at mile 5, 1 gel at mile 9, water at every aid station
  • Sub-90 minute halves: a single gel at mile 5 is usually enough; some elite runners skip fueling entirely

Use the calculator

Our marathon pace calculator works for any race distance — enter 13.1 miles and your goal time to get goal pace and split targets to print on your race-day pace band.