Shed

Free tool · Volume

Weekly Mileage Planner

A week-by-week build from what you are running now to what your block needs, at a rate your tendons can absorb, with the cutback weeks already in it.

Your build

  • Week 1

    20 mi

  • Week 2

    22 mi

  • Week 3

    24 mi

  • Week 4

    20 mi

    Cutback week. Not optional.

  • Week 5

    27 mi

  • Week 6

    29 mi

  • Week 7

    32 mi

  • Week 8

    27 mi

    Cutback week. Not optional.

  • Week 9

    35 mi

  • Week 10

    39 mi

  • Week 11

    40 mi

  • Week 12

    30 mi

    Cutback week. Not optional.

  • Week 13

    40 mi

  • Week 14

    40 mi

Builds at up to 10 percent per stepping week with a cutback every fourth week. The cutback weeks are where the adaptation consolidates and where your tissues catch up.

Stop calculating. Start training.

These numbers are the first 30 seconds of what Shed does.

Shed reads your Apple Health, grounds your VDOT in your actual training — not one race — and writes the whole block: every workout, every pace, adjusted as life happens. The calculator gives you a snapshot; Shed gives you the plan.

Get your plan on iPhone

Why the ceiling is structural

Your cardiovascular system adapts fast. Within two or three weeks of a step up in volume, your heart and lungs are comfortable with it. Tendon, bone and connective tissue take months, and they detrain faster than they retrain.

That gap is where running injuries live. You feel capable of more than your tissues have earned, and the feeling is accurate about your fitness and wrong about your durability. Building slowly is not caution about your aerobic system. It is respect for the parts that take the impact.

Start honestly

The most common way this planner gets misused is entering an aspirational starting point. Your current weekly volume is what you have averaged over the last month, not the best single week you managed in spring.

If you have had a gap of more than two weeks, start below where you left off. Fitness returns quickly and tissue tolerance does not, and the return is the most dangerous phase of any training year.

Frequently asked

Is the 10 percent rule real?
It is a useful ceiling rather than a law. There is no strong evidence for exactly 10 percent, and applying it rigidly is silly at very low mileage, where 10 percent of 8 miles is a single mile. What holds up is the underlying principle: connective tissue adapts more slowly than your cardiovascular system, so the limit on how fast you can build is structural, not aerobic.
Why cutback weeks?
Adaptation happens during recovery, not during load. A cutback every third or fourth week, dropping volume by about a quarter, is where the previous weeks consolidate. Runners who build linearly for eight straight weeks get injured in week seven with remarkable consistency.
How much mileage do I actually need?
For a first marathon, peaking at 35 to 45 miles a week is normal and sufficient. Sub-4 is comfortable at 40 to 45. Sub-3 usually wants 50 to 70. For a half, 25 to 35 for sub-2 and 40 to 55 for sub-90. More is not automatically better; more that you can absorb is.
Should I add distance or add runs?
Runs, usually. Adding a fourth or fifth easy run a week builds durability with less injury risk than making three runs longer. Frequency is the cheaper way to buy volume.
What if I have to miss a week?
Rejoin where the plan is now rather than trying to make it up. One missed week costs almost nothing. Two weeks of running crammed into one is how a missed week becomes an injury.

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