Health⏱ 5 min read
How to Calculate Half Marathon Training Paces for Every Session
Different training runs should be done at different paces — but most runners do everything at roughly the same speed. Here is how to calculate the correct pace for each session type.
Training at the wrong pace is the most common mistake in distance running. Run too fast on easy days (which most people do) and you accumulate fatigue without the aerobic base development those runs are designed for.
Finding Your Easy Pace Range
Easy pace: 60-75% of Max Heart Rate
OR: approximately 90 seconds to 2 minutes slower than race pace/km
If your half marathon target pace is 5:30/km:
Easy run pace: 7:00-7:30/km
(This feels embarrassingly slow to many runners — that's correct)
Talk test: you should be able to speak full sentences comfortably.
If you can't, you're going too fast for an easy run.
The McMillan Method: All Paces from One Race Time
Using half marathon target time of 2:00:00 (5:41/km):
Easy/recovery runs: 7:06-7:51/km
Long run: 6:18-7:06/km
Marathon pace: 5:55/km
Half marathon pace: 5:41/km (race pace)
Threshold (tempo) runs: 5:16/km
VO2 max intervals: 4:55-5:06/km
Speed intervals: 4:30-4:50/km
Each zone serves a different physiological purpose.
Trying to run every session at half-marathon pace:
✗ Easy runs too fast → accumulated fatigue
✗ Intervals too slow → insufficient stimulus
Result: grey zone training that develops neither base nor speed
Calculating Threshold Pace
Threshold pace = pace you can sustain for approximately 60 minutes.
For most recreational runners: 10-15 seconds faster than race pace.
For 2:00:00 half marathon target:
Race pace: 5:41/km
Threshold pace: approximately 5:20-5:30/km
Threshold sessions:
20-minute tempo runs at threshold pace (classic)
Cruise intervals: 5-8 x 1km at threshold with 60s recovery
These develop lactate clearance and running economy.
Interval Pace Calculation
VO2 max intervals: 3-5% faster than race pace
For 5:41/km race pace:
Interval pace: 5:41 x 0.95 = 5:24/km
Standard interval session:
6 x 800m at 5:24/km (4:19 per 800m)
Recovery: jog 400m or equal time
Or:
5 x 1km at 5:24/km (5:24 per km)
Recovery: 90 seconds
Weekly training distribution (evidence-based):
80% easy/long runs (Zone 1-2)
20% quality sessions (threshold and intervals)
This is the "80/20" or polarized model — used by most elite programs
Sample Half Marathon Training Week
Target: 2:00:00 half marathon
Monday: Rest or easy cross-training
Tuesday: 8km easy (7:10/km)
Wednesday: Threshold session — 3km warm up, 20min at 5:25/km, 3km cool down (10km total)
Thursday: 6km easy (7:10/km)
Friday: Rest
Saturday: Long run 16km at 6:20-7:00/km
Sunday: 5km easy recovery (7:30/km)
Weekly: ~45km. Long run: 36% of weekly volume (within recommended range)
One quality session: sufficient for base-building phase