What is an Arbitrary Unit (AU)?

An Arbitrary Unit is the product of session RPE and session duration in minutes, a method called session-RPE load. It has no physical meaning on its own but lets you compare and track total training load week to week on a consistent scale.

How is session load calculated?

Each session's load equals its RPE (one to ten) multiplied by its duration in minutes. A 60-minute session at RPE 6 is 360 AU. Weekly volume is simply the sum of every session's load across the week.

What do monotony and strain tell me?

Monotony is your average daily load divided by its standard deviation; high values mean every session is similar, which raises injury risk. Strain is weekly load multiplied by monotony and captures the combined effect of volume and sameness.

What monotony value is too high?

Foster's original research flagged monotony above roughly 2.0 as associated with higher illness and overtraining risk. If you see a high value, introduce easier and harder sessions so your load is less uniform across the week.

Should I count rest days?

This calculator sums only the sessions you log, so rest days naturally lower your weekly total and increase variation. Tracking volume across a full mesocycle helps you progress load gradually rather than spiking it.

Climbing Weekly Volume Calculator

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Climbers periodise like any other strength athlete, but climbing load is hard to pin to a single number. This calculator uses the established session-RPE method to turn each climb into Arbitrary Units, then sums your week so you can progress load deliberately instead of by feel.

How it works

Every session’s load is the product of how hard it felt and how long it lasted:

session load (AU) = session RPE (1-10) × duration (minutes)
weekly volume     = sum of all session loads

From the daily loads the tool also computes Foster’s monotony and strain, which reveal whether your week is too uniform:

monotony = mean daily load / standard deviation of daily load
strain   = weekly volume × monotony

Example and tips

Three sessions of 60 minutes at RPE 6, 8 and 5 give loads of 360, 480 and 300 AU for a weekly volume of 1,140 AU. If every session were identical the monotony would climb and so would the strain — a warning to mix easy mileage days with hard projecting sessions. Progress weekly volume by roughly 5 to 10 percent at a time, and pull it back during deload weeks to let your fingers and tendons recover.