RPE & Training Load Calculator

Training Load Guide

What should I know about Session RPE and Training Load?

Session RPE (sRPE) method: training load = RPE × duration in minutes. Also called the Foster method (Dr Carl Foster, 1998). This gives an Arbitrary Unit (AU) value. Example: 60-minute run at RPE 6 = 360 AU. 30-minute HIIT at RPE 8 = 240 AU. 90-minute easy yoga at RPE 3 = 270 AU. sRPE correlates well with physiological measures (lactate, heart rate) and is more practical for tracking all training types including strength sessions (where heart rate poorly reflects load). Weekly load = sum of all sessions' RPE multiplied by duration, giving a single combined figure to track total training stress across a full week.

What's the key thing to understand about Acute:Chronic Workload Ratio?

ACWR = acute load (this week) / chronic load (4-week rolling average). The 'sweet spot' for adaptation without excessive injury risk: ACWR 0.8-1.3: safe zone. Adequate training stimulus without spike risk. ACWR < 0.8: undertraining — may lose fitness or underperform. ACWR 1.3-1.5: caution zone — moderate increase in non-contact injury risk. ACWR > 1.5: danger zone — significant spike in injury risk. This framework comes from sports science research, particularly rugby (Gabbett, 2016). It applies broadly across many sports, not just rugby, as a way of flagging when training load has increased too sharply relative to recent history.

What should I know about The 10% Rule?

The classic 10% rule: do not increase total weekly training load by more than 10% from one week to the next. This is a simplified version of ACWR thinking. More nuanced guidance: 10% increase per week is a ceiling, not a target. After a period of higher load: a lower-load recovery week (60-80% of peak) before building again. After injury or illness: return gradually — your chronic load has fallen, so your acute load must be low too. Common mistake: returning from 2 weeks off sick and immediately resuming the previous training load, which is exactly the kind of acute spike relative to a lowered chronic baseline that raises injury risk.

What do I need to know about RPE Scale and Honest Self-Assessment?

The 10-point Borg CR10 scale: 0 = nothing. 1 = very light. 2 = light. 3 = moderate. 4 = somewhat hard. 5 = hard. 6 = harder. 7 = very hard. 8 = very very hard. 9 = near maximal. 10 = maximal. Common errors: athletes often rate RPE too low (social desirability — appearing tough). RPE should be assessed at session END, not during — easier to be objective. Different activities feel different at the same physiological effort: RPE is subjective and personal to each athlete. Zone 2 training — easy, conversational effort — should genuinely feel easy on the RPE scale, which is a common area where athletes unintentionally train harder than intended.

How Does RPE-Based Training Differ From Percentage-Based Training?

Percentage-based training prescribes load as a fixed percentage of a tested or estimated 1RM, which is precise on paper but assumes that percentage represents the same relative difficulty every single session — an assumption that breaks down on days affected by poor sleep, stress, illness, or accumulated fatigue, when a weight that is normally 80% of 1RM can feel considerably harder. RPE-based training instead prescribes a target difficulty (for example, 'a weight you could do for 2 more reps') and lets the actual load vary session to session based on how the body is performing that day, which tends to produce more consistent relative training stress across a training block even though the absolute weights used will fluctuate. Many modern programs use a hybrid approach — percentage-based targets with an RPE check (if the prescribed percentage doesn't match the target RPE, the lifter is instructed to adjust load up or down) — combining the planning benefit of percentages with the day-to-day accuracy of RPE.

Why Is RPE Harder to Use Accurately for Beginners Than Experienced Lifters?

Accurately judging RPE — specifically, estimating how many more reps could be done before failure (reps in reserve) — is a skill that improves with training experience, because it requires an internal sense of how fatigue accumulates within a set that most beginners haven't yet developed; new lifters very commonly either badly underestimate their remaining reps (stopping sets far from true fatigue, thinking they're near failure when they're not) or badly overestimate them (continuing well past the point where form breaks down). This is part of why RPE-based programs are often recommended more cautiously for beginners, sometimes paired with occasional true failure sets under supervision to help calibrate their sense of what RPE 9-10 actually feels like, whereas experienced lifters who have trained to failure many times before generally rate RPE with meaningfully higher accuracy and consistency, making RPE prescriptions more reliable for them.

How Can RPE Be Combined With Velocity-Based Training?

Velocity-based training (VBT) uses a device — often a small sensor attached to the barbell — to measure how fast the bar moves on each rep, providing an objective data point that complements the subjective nature of RPE. The two work well together because RPE captures the lifter's internal sense of effort, which can be affected by sleep, stress, and daily readiness, while bar speed provides an external, consistent measure of how much the body actually produced on that rep, independent of how it felt. In practice, many lifters find that bar speed and RPE usually track together — slower bar speed corresponds to higher perceived effort — but when the two disagree, it's informative: a rep that moved unusually slowly despite feeling only moderately hard (low RPE but slow velocity) can indicate accumulated fatigue the lifter hasn't consciously registered yet, while a rep that moved fast despite feeling surprisingly hard can suggest the RPE rating was inflated by factors like low motivation or distraction rather than genuine physical strain. Some programmes use velocity as an autoregulation tool directly — stopping a set once bar speed drops below a defined threshold for that exercise, rather than stopping at a pre-set rep count — which effectively formalises what experienced lifters already do by feel using RPE, but with more objective precision, particularly useful for lifters still learning to rate their own effort accurately.

Worked Example: Reading RPE Against Heart Rate Over a Training Block

RPE becomes most useful when it is compared with heart rate and pace over time rather than read in isolation on a single day. If a runner's easy pace consistently feels like RPE 6 while heart rate for that same pace drifts from 150bpm down to 142bpm over six weeks, that combination (same subjective effort, lower heart rate) is a reliable sign of improving aerobic fitness. Conversely, if the same pace starts to feel like RPE 8 at an unchanged heart rate, that usually signals accumulating fatigue, illness, heat, or under-recovery rather than a fitness problem, and is a cue to schedule an easier week rather than push through.

The Borg CR10 Scale at a Glance

Most RPE-based training, including the 1-10 scale used in this calculator, traces back to the Borg Category-Ratio (CR10) scale, developed to give a simple, consistent way of describing effort that correlates reasonably well with heart rate and blood lactate across a wide range of people.

These descriptions are deliberately approximate, since the same number means a genuinely different physical intensity for a trained athlete compared with someone new to structured exercise; RPE measures perceived effort relative to a person's own capacity, not an absolute, universal intensity.

RPE in Cardio Training vs Resistance Training

RPE is used slightly differently depending on the type of training. In cardio or endurance training, RPE typically describes the overall effort of sustaining a pace or intensity over time, closely tracking breathing rate and heart rate. In resistance training, RPE is more often used set by set, commonly expressed as 'reps in reserve', describing how many more repetitions could have been performed before technical failure on that set. An RPE of 8 on a lifting set generally means roughly two more reps were available before failure, while an RPE of 10 means the set was taken to true failure. Both uses share the same underlying idea of perceived effort relative to personal capacity, but the practical anchor, pace and breathing for cardio versus reps in reserve for lifting, differs by context.