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Acute:chronic workload ratio (ACWR) calculator

Short answer

The acute:chronic workload ratio divides this week's training load by your average weekly load over the last four weeks. Gabbett (2016) described 0.8–1.3 as a training "sweet spot" and 1.5 or more as a "danger zone" for injury. Later work argues the ratio has no proven causal link to injury, so treat it as a check on how fast you are adding load.

Last reviewed 12 October 20262 published sourcesNot medical advice

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Session load helper

Session-RPE load: minutes of training × how hard it felt on a 0–10 scale. Add up a week's sessions for the weekly load.

min

Session load

420 AU

arbitrary units

Acute:chronic workload ratio

Weekly totals, oldest first. Use the same load measure for every week.

ACWR (rolling 4-week)

1.22

2600 ÷ 2125

Uncoupled ACWR

1.32

this week ÷ previous 3 weeks

Zone

0.8–1.3 sweet spot

This week is in line with what you have been doing — the range Gabbett described as the sweet spot.

How the acute:chronic workload ratio works

Acute load is your recent training, usually the last week. Chronic load is the rolling average of the last 3–6 weeks: what your body has been prepared for. When acute load is high and chronic load is low, you have added work faster than you have built fitness, and the ratio climbs above 1 (Gabbett, 2016). This calculator uses four weeks and includes the current week in the average (the common “coupled” method), and also shows the uncoupled version.

ACWR zones described by Gabbett (2016)
RatioDescription
Under 0.8Lighter than recent training
0.8–1.3“Sweet spot”: injury risk was low in the studies reviewed
1.3–1.5Between the sweet spot and the danger zone
1.5 or above“Danger zone”: injury risk was high in the studies reviewed

The caveats

ACWR is popular and contested. Impellizzeri and colleagues argue that no study has properly estimated a causal effect of the ratio on injury, that dividing by an average that already contains the acute week creates statistical artefacts, and that there is no evidence supporting ACWR for injury-reduction decisions (Impellizzeri et al., 2020). That is why the calculator also shows the uncoupled ratio (this week against the three weeks before it).

Used loosely, it is still a quick way to notice a sudden spike: a week far above what you have been doing is worth a second look at sleep, soreness and how sessions feel. Our overtraining page explains why no single number, this one included, should decide your training on its own.

Training load, tracked for you

Reps compares your recent workout load with your longer-term baseline and reads it alongside your readiness, resting heart rate and HRV, so a fast build-up shows up early.

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Common questions

What is a good acute:chronic workload ratio?

Gabbett's 2016 review described 0.8–1.3 as the sweet spot where injury risk was low in the studies he reviewed, and 1.5 or above as the danger zone. These ranges came mostly from team-sport athletes.

How do you calculate ACWR?

Divide the acute load (usually the last 7 days) by the chronic load (the rolling average weekly load over the last 3–6 weeks; this calculator uses 4). A common way to measure load is minutes of training multiplied by a 1–10 effort rating, known as session-RPE load.

Is ACWR reliable?

It is debated. Impellizzeri et al. (2020) concluded there is no evidence supporting the use of ACWR to reduce injury risk, and that the ratio's statistical properties make it an inaccurate metric. It is still a simple way to notice a sudden jump in training.

Sources

Figures on this page were checked against these publications on 12 October 2026.

  1. Gabbett TJ. The training-injury prevention paradox: should athletes be training smarter and harder? British Journal of Sports Medicine. 2016;50(5):273–280. doi.org/10.1136/bjsports-2015-095788
  2. Impellizzeri FM, Tenan MS, Kempton T, Novak A, Coutts AJ. Acute:chronic workload ratio: conceptual issues and fundamental pitfalls. International Journal of Sports Physiology and Performance. 2020;15(6):907–913. doi.org/10.1123/ijspp.2019-0864

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