Sub-4 Hour Marathon — Training Paces and Fitness Profile
Sub-4:00 is the most commonly cited marathon goal in recreational running. It requires real endurance, consistent volume over months, smart pacing on race day, and honest easy-day discipline. The training paces here represent what a genuine sub-4 marathoner actually runs during their training cycle.
Quick answer: To break Sub-4:00:00 in the Marathon (RPI 37.9), your training paces are: easy 10:20/mi, threshold 8:05/mi, interval 7:03/mi. Equivalent fitness: Half Marathon 1:56:07, 10K 52:22.
Training paces for Sub-4:00:00 Marathon
RPI 37.9 · Goal: 3:59:59 · All paces in min/mile
Calculated from Daniels/Gilbert oxygen cost equations. Easy pace means "this pace or slower."
Equivalent race fitness
These are the predicted equivalent times at other distances for a runner with RPI 37.9 — assuming comparable training for each distance.
Half Marathon
1:56:07
8:51/mi
10K
52:22
8:26/mi
5K
25:14
8:07/mi
Training approach for Sub-4:00:00 Marathon
For sub-4 marathon, marathon-pace runs and long runs at easy pace are the two most critical training elements. Marathon-pace work — running the final miles of a long run at goal pace — teaches your body to maintain effort when glycogen is depleted, which is exactly what the final 10K of the marathon demands. Easy running makes up 80% or more of weekly volume and builds the aerobic base and fat-oxidation capacity that sustains marathon effort for hours. Threshold running matters, but marathon pace and easy base are the top priorities.
Calculate your current training paces
The table above shows paces for Sub-4:00:00 Marathon fitness. Enter your current race time to see where you are now and how far from the goal you sit.
Training Pace Calculator
These paces are based on your race time — not your body
The Daniels/Gilbert formula predicts training zones from a single race result. StrideIQ goes further: it tracks how your body specifically responds to threshold and interval work — which sessions produce your biggest gains, how quickly you recover, and when your fitness is peaking. Population formulas start the conversation. Your individual response data finishes it.
Common questions
What training paces does a sub-4 hour marathon runner use?
To train for a sub-4:00:00 marathon (3:59:59), your training zones are: Easy 10:20/mi, Marathon 8:35/mi, Threshold 8:05/mi, Interval 7:03/mi, Repetition 6:29/mi. Your marathon-pace training runs target 8:35/mi — your long run easy days should be at 10:20 or slower. The gap between these paces is deliberate: different adaptations, different sessions.
What is the most common mistake runners make when chasing a sub-4 marathon?
Going out too fast on race day, and running easy training days at marathon pace. Both errors stem from the same cause: underestimating how much the marathon punishes pace that feels "comfortable" early. Easy training pace for a sub-4 runner (10:20/mi or slower) often feels almost embarrassingly slow. But running easy days at marathon pace leaves no adaptation reserve for the quality sessions that build fitness. And starting a marathon at a pace that feels good virtually guarantees a painful final 10K.
What half marathon time does sub-4 marathon fitness predict?
Sub-4:00 marathon fitness (RPI 37.9) projects to approximately 1:56:07 for the half marathon — assuming comparable training for the half distance. Because the half marathon is run at a higher percentage of VO2max than the marathon, runners who are specifically marathon-trained (high volume, long runs, marathon-pace work) may underperform their half marathon equivalent until they do more half-specific work. The equivalency reflects aerobic capacity, not single-distance peaking.
Other goal pace guides
Paces calculated using the Daniels/Gilbert oxygen cost equations (1979). All values derived from the same formula used by the StrideIQ training pace calculator. Goal times use the target-minus-one-second convention (e.g., sub-20 = 19:59 input).