Sub-4 Marathon Splits Calculator (KM)
Tip: aim to stay within ±5–10 sec/km. If you drift, correct gently over the next 1–2 km (avoid surging).
Sub-4 Pace Band (3:59:59 — 5:41/km)
Key checkpoints for an even-paced 3:59:59 marathon (≈ 9:09/mi).
| Distance | Cumulative time |
|---|---|
| 5 km | 0:28:26 |
| 10 km | 0:56:52 |
| 15 km | 1:25:19 |
| 20 km | 1:53:45 |
| Half (21.1) | 2:00:00 |
| 25 km | 2:22:11 |
| 30 km | 2:50:37 |
| 35 km | 3:19:04 |
| 40 km | 3:47:30 |
| Finish (42.195) | 3:59:59 |
Cue: calm early → steady to 30k → protect pace 30–40k → push after 40k.
Key Split Times for Sub-4
These are the checkpoints most runners track on race day (cumulative time for 3:59:59).
Who sub-4 pace suits
- First-time or improving marathoners with consistent weekly running and a steady long-run base.
- Runners who can hold ~5:41/km comfortably on tired legs (strong aerobic durability).
- Anyone who wants a clear pacing structure: steady early and disciplined fueling to avoid the late fade.
Common mistakes at sub-4 pace
- Banking time early: going 10–20 sec/km too fast in the first 10 km and paying for it after 30 km.
- Fueling too late: waiting until you feel flat before taking your first gel (start early, stay consistent).
- Pace yo-yo: surging after a slow km instead of smoothing it out over the next 1–2 km.
- Ignoring conditions: forcing exact pace into heat/headwind/hills instead of pacing by effort.
Pace conversions for Sub-4 (3:59:59)
Quick reference for track sessions and race-day math.
Note: GPS and course factors can add noise. Use this as a guide, not a guarantee.
Sub-4 race strategy (simple, effective)
Most sub-4 attempts fail from early pace creep or late fueling gaps. Keep it boring early, then cash it in late.
- First 10 km: run controlled at ~5:42–5:45/km (you can earn time later).
- 10–30 km: settle into goal pace and protect rhythm through aid stations.
- 30–40 km: focus on form cues (cadence + relaxed shoulders) and keep carbs coming.
- 40 km to finish: commit—use the 40k split as permission to push.
If it’s hot/hilly: pace by effort and accept slightly slower early splits to avoid a late blow-up.
Pacing plan (simple and realistic)
- 0–5 km: start controlled—avoid banking time early.
- 5–30 km: settle into ~5:41/km and stay smooth (minimal surges).
- 30–40 km: protect pace—focus on cadence and even effort.
- 40–42.2 km: use the 40 km split as permission to push.
Fueling (quick template for sub-4)
Practice this in training. Many runners aim for roughly 40–70g carbs/hour depending on tolerance.
- Start early: first gel around 20–25 minutes.
- Repeat: every 25–35 minutes with water.
- After 30 km: keep fueling even if it feels hard to take in.
Training tie-in (what supports a 3:59:59 marathon)
These are general training patterns that often support a 3:59:59 goal. Use effort and recovery as the primary guide.
Typical weekly structure
- Volume: 45–85 km/week (typical) (individual needs vary)
- Long run: 2:10–2:50, mainly easy with a controlled final 20–30 min
- 1 quality session: threshold or hills (keep it controlled)
- 1 marathon-specific session: marathon-pace / steady segments
- Easy runs: often around 6:41–7:31/km (roughly +60–110 sec/km slower than goal pace)
Example key workout
One marathon-specific option: 3 × 12 min at ~marathon pace (5:41/km) with 5 min easy between. Keep the first rep smooth, and stop early if form breaks.
Simple pacing anchors
5:41/km
9:09/mi
6:01–6:21/km
6:41–7:31/km
Pace Chart (Per KM)
Quick reference chart in kilometres. Adjust the goal time above to explore sub-4 pacing.
Sub-4 (3:59:59) Marathon Pacing FAQ
What pace per km is a sub-4 marathon?
To break 4 hours you need to average about 5:41 per km (or slightly faster) over 42.195 km.
What pace per mile is sub-4 marathon pace?
Sub-4 marathon pace is roughly 9:09 per mile (or slightly faster).
What are the key split times for a sub-4 marathon?
Key markers for a 3:59:59 marathon: 5k 0:28:26, 10k 0:56:52, half 2:00:00, 30k 2:50:37, 40k 3:47:30, finish 3:59:59.
What half marathon time predicts sub-4?
A comfortable half around ~1:52–1:58 (depending on endurance and training) is often consistent with a sub-4 attempt when pacing and fueling are good.
Should I start faster to bank time for sub-4?
Usually no. A controlled first half at goal effort gives the best chance of holding pace after 30 km.
Note: This is a planning tool only. Official results depend on course and conditions.