How it works
VDOT (from your recent race) → training paces → periodised volume ramp with cutback weeks and a taper.
The pipeline has three stages. Your recent race becomes a VDOT score — the same engine behind the race-time predictions — and that score fixes your easy, threshold, interval, and marathon paces. The available weeks are then split into phases with distinct jobs: Base stacks easy mileage plus 6×20-second strides, Build centers on threshold work such as 4–5×6 minutes or a 20-minute steady tempo, Peak brings three-minute VO₂ max repeats and long runs finishing at marathon effort, and the final 2–3 weeks taper (plans of 12 weeks or longer get the full 3). Volume climbs about 8–10% per week, in line with ACSM progression guidance, and every fourth week cuts back roughly 18% so the load can be absorbed. The long run grows as a capped share of the week — near 30%, never beyond about 22 miles (35 km) — and peaks before the taper begins. To sharpen the Peak targets, dial in your goal marathon pace and test the goal with a set of Yasso 800s.
Sources
- Daniels — phases, paces and periodisation Jack Daniels, “Daniels' Running Formula,” 3rd ed., Human Kinetics (2014). Source for the Base/Build/Peak/Taper structure and the E/M/T/I training paces derived from VDOT.
- ACSM — progression of training load American College of Sports Medicine, “ACSM’s Guidelines for Exercise Testing and Prescription,” 11th ed. (2021). Basis for the conservative ~10%-per-week volume progression and recovery (cutback) weeks.
- Daniels–Gilbert VDOT model Jack Daniels & Jimmy Gilbert, “Oxygen Power: Performance Tables for Distance Runners” (1979) — the VDOT that seeds this plan.
- Hal Higdon — marathon plan length & weekly mileage norms Hal Higdon, “Marathon Training Programs” (halhigdon.com): Novice plans run 18 weeks and peak around 30–40 mi/week; intermediate/advanced plans build to roughly 40–55+ mi/week. Source for the population norms on typical plan length and peak weekly mileage (not the runner’s own VDOT-scaled volume, which the calculator computes).
- Boston Athletic Association — marathon training guidance Boston Athletic Association, “Boston Marathon Training” (baa.org). Corroborates the conventional 16–20-week build for typical marathoners and a long run building toward ~20 miles.
FAQ
How many weeks should a marathon plan run?
Most marathoners land in the 16–20 week range. A runner with a durable base can prepare in about 12, while first-timers often do better stretching toward 18–24 so the mileage ramp stays gentle. Enter the window you truly have: the phases compress or expand to fill it, and the taper is always protected.
What peak mileage will I get?
Whatever your VDOT and goal distance justify — it is computed, not copied from a chart. For context, published beginner marathon plans top out around 30–40 mi (50–65 km) weekly, intermediate ones around 40–55 mi (65–90 km), and long runs classically grow toward 20 mi (32 km). Your own peak week may sit outside those norms, and that is the point.
Why does the mileage drop every fourth week?
Those are cutback weeks, trimmed by roughly 18%. The body adapts while recovering, not while stacking load, and a scheduled down-week is the cheapest injury insurance a self-coached runner can buy. Resist the urge to skip them and bank extra miles.
What actually changes between the four phases?
The emphasis and the key workout. Base is easy volume with strides; Build introduces sustained threshold running; Peak stacks VO₂ max intervals and marathon-pace long-run finishes; the Taper keeps small touches of speed while total volume falls away so you start fresh. Weekly volume and the long run follow the same arc underneath.
Is every week tied to a calendar date?
Yes. The schedule counts backwards from the race day you enter: the bottom row is race week and each row above begins seven days earlier. You can spot immediately which phase collides with a vacation or a work crunch — and re-plan before committing.
Can I export or print the schedule?
Both work. The dated plan downloads as an .ics calendar file that imports into Google Calendar, Apple Calendar, or Outlook, and the page prints cleanly — or saves to PDF — if paper on the fridge is more your style.
What if I only have a few weeks left?
The plan degrades gracefully instead of refusing. Very short windows drop base work, spend the remaining time on race-specific sessions, and still protect a short taper of one to two weeks. Expect sharpening rather than transformation, and keep the goal honest.
How reliable are the workout paces?
Exactly as reliable as the race behind them. A recent all-out result produces paces you can hit; a soft or stale one skews every session in the plan. If workouts consistently feel wrong, rebuild the plan from a fresher race instead of forcing the numbers.
Does this replace a coach?
No — think of it as scaffolding. A coach reacts to how each week actually went, adjusts around injury and life stress, and knows when breaking the rules is correct. Keep the generated schedule as your default and change it whenever your body files a complaint.
A generated schedule cannot see your injury history, sleep, or life stress, and mileage that fits the model may not fit your legs. Build up gradually, drop sessions freely when something hurts, and treat the plan as general training information — a starting framework, not medical guidance or a substitute for coaching.