Enter a recent race time to see the paces you can train at today.
Sub-3:45 marathon is meaningful competitive fitness — well into the upper tier of recreational marathon runners. Getting here requires consistent volume, real long runs, and structured quality work over one or more training cycles.
Quick answer: To break Sub-3:45:00 in the Marathon (RPI 41), your training paces are: easy 9:39/mi, threshold 8:02/mi, interval 7:24/mi. Equivalent fitness: Half Marathon 1:48:35, 10K 48:58.
RPI 41 · Goal: 3:44:59 · All paces in min/mile
Calculated from StrideIQ's RPI equations. Easy pace means "this pace or slower."
These are the predicted equivalent times at other distances for a runner with RPI 41 — assuming comparable training for each distance.
Half Marathon
1:48:35
8:17/mi
10K
48:58
7:53/mi
5K
23:36
7:36/mi
For sub-3:45 marathon, the primary training levers are 18–20 mile long runs at easy pace and one threshold session per week. Marathon-pace miles added to the end of long runs are the most race-specific preparation. Total weekly volume of 30–45 miles with one threshold session is the effective structure for this standard.
For sub-3:45:00 (3:44:59): Easy 9:39/mi, Marathon 8:35/mi, Threshold 8:02/mi, Interval 7:24/mi. RPI 41. Marathon training pace (8:35/mi) is what you practice in the final miles of long runs when your legs are already tired. Easy pace (9:39/mi) is where all other running happens.
Not running enough miles at genuinely easy pace. Runners who target sub-3:45 often run 3–4 days per week but keep all runs at moderate effort. Slowing easy days to 9:39/mi or slower (which often feels too slow) allows recovery and enables the occasional hard session to generate real adaptation. Adding a 5th easy run often produces more improvement than making existing runs harder.
Sub-3:45 marathon fitness (RPI 41) projects to approximately 1:48:35 half marathon potential. If you have run a half marathon near this time recently, you have the aerobic capacity for a sub-3:45 marathon — with 20-mile long runs and full marathon preparation.
Paces calculated using StrideIQ's RPI equations. 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).