What is peak week in marathon training?

Peak week is the highest mileage week in your training plan, typically occurring 3-4 weeks before race day. It represents the culmination of your mileage build-up before the taper begins.

How far should my longest run be?

For a marathon, your longest run should be 30-35 km (about 60-70% of race distance). For a half marathon, aim for 18-21 km. Your long run should make up about 30-35% of your peak weekly volume.

How do I safely increase to peak mileage?

Follow the 10% rule — increase weekly mileage by no more than 10% per week. Include a step-down week every 3-4 weeks where you reduce volume by 20-25% before building again.

Should peak week include quality sessions?

Yes, but reduce the intensity of quality sessions slightly. The goal of peak week is total volume rather than speed. Include one tempo or race-pace session but keep it moderate.

RunCalcs

Peak Week Calculator — Plan Your Highest Mileage Week

Calculate your peak training week volume and run distribution before taper.

Current Weekly Distance

Weeks Until Race

Runs per Week

Race Distance

How We Calculate This

Peak Week Volume Calculation

Peak weekly volume is calculated from your current mileage and race distance:

Peak Volume = Current Weekly km x Distance Multiplier

Marathon training typically requires a peak week of 1.5-1.6x your base mileage. The long run makes up 30-35% of peak volume, with remaining kilometres distributed across other training runs. The calculator also estimates how many weeks you need to safely reach peak volume using the 10% progression rule.

Frequently Asked Questions

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Last updated: February 2026

All calculations are estimates. Always consult a coach or medical professional for personalised training advice.