Marathon Taper Calculator
Calculates the recommended weekly training volume for each week of your pre-race taper, scaling down from peak mileage based on your recovery rate, taper length, and race distance. Ideal for marathon and ultramarathon preparation.
Last updated: May 2026
About this calculator
Tapering is the structured reduction of training load in the weeks before a race to allow muscles, connective tissue, and the central nervous system to recover while retaining fitness. The formula used here is: Volume = peakWeeklyMiles × recoveryRate^weeksToTaper × (raceDistance / 42.195). Peak weekly mileage is your highest consistent training week before taper begins. The recoveryRate (a value between 0 and 1, e.g. 0.75) is raised to the power of weeksToTaper to produce an exponential decay — each successive taper week retains that fraction of the previous week's volume, mirroring how coaches traditionally step mileage down by 20–30% per week. The term raceDistance / 42.195 scales output proportionally for races shorter or longer than the standard marathon distance (42.195 km). The result is the target volume in miles for a given week of the taper.
How to use
Say your peak weekly mileage is 50 miles, you have a 3-week taper, your recovery rate is 0.75, and you are running a full marathon (42.195 km). Week 3 out (weeksToTaper = 3): 50 × 0.75³ × (42.195/42.195) = 50 × 0.422 × 1 = 21.1 miles. Week 2 out (weeksToTaper = 2): 50 × 0.75² × 1 = 50 × 0.5625 = 28.1 miles. Week 1 out (weeksToTaper = 1): 50 × 0.75¹ × 1 = 37.5 miles. Race week itself uses weeksToTaper = 0, giving 50 × 1 × 1 = 50 — so race week volume is capped at peak, and you would manually set it to a short shakeout run.
Frequently asked questions
How many weeks should I taper before a marathon?
Most coaches recommend a taper of 2–3 weeks for a marathon, with 3 weeks being the most common prescription for high-mileage runners (above 60 miles per week) and 2 weeks suitable for lower-mileage trainees. The exponential decay built into this calculator means a 3-week taper with a 0.75 recovery rate drops you to about 42% of peak volume by the first taper week — a clinically meaningful reduction that allows glycogen supercompensation and soft-tissue repair. Tapering too aggressively (recovery rate below 0.6) can leave you feeling flat and undertrained on race day, while too little reduction risks arriving fatigued.
What recovery rate should I use in a marathon taper calculator?
A recovery rate of 0.70–0.80 is typical, corresponding to a weekly mileage reduction of 20–30% per step, which aligns with the most widely cited coaching guidelines. Beginners and injury-prone runners often benefit from a more aggressive taper (0.65–0.70), while experienced high-mileage runners may use 0.80 to avoid losing their aerobic edge. The right value also depends on how many taper weeks you have: a 2-week taper at 0.70 and a 3-week taper at 0.80 can produce similar total taper loads, so adjust both parameters together.
How does race distance affect taper volume in this calculator?
The raceDistance / 42.195 multiplier scales the calculated volume proportionally to the standard marathon. For a half-marathon (21.1 km), the multiplier is approximately 0.50, halving the taper volume — appropriate because shorter races require less recovery stress. For a 50-mile ultramarathon (roughly 80 km), the multiplier rises to about 1.90, reflecting the greater cumulative fatigue of ultra-distance racing and the need to arrive with well-stocked glycogen and repaired muscles. This scaling ensures the calculator remains useful across a range of race types without needing separate formulas.