Running Intensity Distribution by Distance

Describe your running week by distance

Enter a complete week's total and divide that distance into easy, moderate and hard categories. Use 0 for a category you did not run. The three entries must add up to the weekly total. The calculator reports your distribution without declaring that it is optimal or diagnosing overtraining.

This form measures distance, not time in heart-rate zones and not the number of sessions. You do not need to connect Strava. The categories are your assignments; the calculator cannot determine physiological thresholds from mileage.

Assign categories consistently

Use one clearly recorded classification method across the runs you compare. Easy, moderate and hard are descriptive groups here, not universal numbered watch zones. A three-zone research model and a five-zone watch model do not have interchangeable zone numbers. Use the training-zone comparison to identify the method, or the heart-rate application guide to investigate a reading before assigning it to a category.

Count the easy warm-up, between-interval recovery jogging and cool-down in the category they actually belong to; do not label the entire distance of an interval outing “hard” merely because the session contains hard repetitions. If your log cannot separate these distances, record that uncertainty rather than assume precision.

The calculation

For each category:

Category percentage = category distance ÷ total reported distance × 100.

The total must be greater than zero. Percentages display one decimal place and may total 99.9% or 100.1% because of rounding. If category distances do not match your weekly total, the calculator asks you to reconcile the entries first.

One week, three different answers

The following is an illustrative arithmetic example, not a recommended training week. Assume an athlete recorded four sessions and assigned their component distances and times as follows:

Distance method (this calculator): 20 total miles give 70.0% easy, 15.0% moderate and 15.0% hard.

Time method: 182 total minutes give 76.9% easy, 13.2% moderate and 9.9% hard. This uses actual category minutes, not the distance inputs above as a substitute for minutes.

Session method: If each whole outing is assigned by its main purpose, the four sessions give 50% easy, 25% moderate and 25% hard. That convention counts the warm-up inside a moderate/hard session differently from the component methods.

The week did not change. The question and counting method did. Keep the method visible when comparing your log with a study, a coach's framework or someone else's training.

What about 80/20?

Research on experienced endurance athletes often describes a large proportion of low-intensity training. Seiler's review includes observations reported by session, in athletes training much more frequently than many recreational runners (Seiler, 2010). That is not a universal requirement for exactly 80% of every runner's miles, nor a validation of an automated score for this tool.

This calculator therefore has no experience-based target, “gray zone” warning, or instruction to add hard running to improve a grade. Use the result to describe the week and discuss its context, not to manufacture a percentage.

Check an all-easy week

For 40 total miles, enter 40 easy, 0 moderate and 0 hard. The result is 100.0%, 0.0%, 0.0%. The tool does not replace either zero with a sample value. An entirely zero-distance week has no distribution and returns an explanation instead.

Compare weeks without changing the definitions

First reconcile the entries with your log. Then consider why the distribution differs: session purpose, available time, recent changes or measurement differences. The numbers alone do not establish the right next workout.

Use the weekly mileage comparison to examine distance change separately. Neither result should be interpreted as an injury prediction or a fitness test.