Weekly mileage needed to break 3 hours in the marathon

Ask a group of marathoners how much you need to run each week to break three hours and you’ll hear everything from “50 miles is plenty” to “you won’t manage it without 100.” The truth lies in how much your body can handle – but there’s no escaping that higher mileage is strongly correlated with faster marathons.

The marathon is a test of endurance unlike any other distance. You can fake your way to a decent 10K or even a half marathon on speed and threshold work with modest mileage, but the full 26.2 demands hours of steady running. More mileage doesn’t just strengthen your lungs. It hardens muscles, tendons and joints to withstand the pounding, and it trains your mind and metabolism to keep working late into the race. When you see runners crumbling in the last 10K, it’s often not a lack of willpower but a lack of cumulative training volume that brings them down.

If your target is to go under three hours, most coaches point to a peak range of 60–70 miles (95–110km) per week as a realistic benchmark. Crucially, this isn’t limited to a neat “calendar week” on your training plan – what matters is any rolling seven-day period. When you review your training log, the most telling marker is not a single big week but the mileage you can sustain consistently from one week to the next without breakdown.

Mileage alone, however, isn’t enough. The 80:20 rule still applies: most miles easy, a smaller proportion faster. Easy running is sometimes dismissed as “junk,” yet it’s the bedrock that allows your body to absorb the harder sessions. Without that aerobic padding, the quality workouts simply don’t stick. The long miles are what give those sharper efforts a lasting effect.

Many sub-3 runners eventually progress into the 80–100 mile (130–160km) range. At that point, the real focus is on consistency rather than the headline number. A block of steady 70-mile weeks will build more resilience and aerobic depth than one heroic 100-mile effort followed by burnout and missed training. The art is to expand gradually – carving out extra runs in the morning, experimenting with occasional doubles, or making lifestyle adjustments so the extra training time fits without constant stress.

None of this means you should neglect recovery. High mileage only pays off if you can absorb it, and that requires sleep, nutrition and restraint on the easy days. Runners who learn to slow down enough to carry the load usually go further than those who insist on pushing every run. If you want sub-3 badly enough, you need to make the space for the mileage and the recovery alike.

Mileage isn’t everything. But for the marathon specifically, it’s the single most important lever you can pull. Get it right, and you won’t just arrive fitter – you’ll arrive tougher, more resilient, and ready to hold form when the real race begins in the final 10K.