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Training Load Calculator (ACWR)

Acute:Chronic Workload Ratio, from Gabbett (2016). See how your last 7 days compare with your average week of the last 28, before your next training block.

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For reference only. The ratio is arithmetic; the injury risk bands around it are disputed and were the subject of a retraction request to the journal that published them. Individual response to training load varies. Consult a sports physiotherapist for personalised advice.

28-day total ÷ 4 = chronic weekly average. ACWR = acute ÷ chronic avg.

1.14

In line with your base

Your last 7 days against your average week of the last 28.

Acute: 80 km · Chronic avg: 70.0 km/wk

This week is close to your average week of the last 28 days. This is the band most training weeks fall in.

00.81.31.52.0+

ACWR reference zones

ACWRZoneName in the literature
< 0.8Well below your baseUndertraining, deconditioning
0.8 to 1.3In line with your baseThe "sweet spot", claimed lowest risk
1.3 to 1.5Above your baseCaution, claimed elevated risk
> 1.5Far above your baseThe "danger zone", claimed high risk
Also useful: Check HRV readiness → · Calculate swim training zones →

Source for the ratio: Gabbett TJ (2016), The training and injury prevention paradox, British Journal of Sports Medicine, 50(5), 273 to 280. Source for the dispute over its thresholds: Impellizzeri, Woodcock, McCall, Ward and Coutts, The acute-chronic workload ratio-injury figure and its 'sweet spot' are flawed, a retraction or errata request to the same journal; Wang et al. 2020, Sports Medicine; and Impellizzeri et al. 2020, Sports Medicine 51(3), 581 to 592.

ACWR explained

The thresholds are disputed, and you should know by whom

Gabbett (2016) formalised the ratio in the British Journal of Sports Medicine. Acute load, the last 7 days, is divided by chronic load, the average week of the last 28, giving a number that describes how hard this week was against your recent base. That arithmetic is not in question. What is in question is reading it as injury risk.

What happened to the figure

Impellizzeri, Woodcock, McCall, Ward and Coutts filed a request with the journal for retraction or errata of the ACWR and injury figure, under the title The acute-chronic workload ratio-injury figure and its 'sweet spot' are flawed. Their objection was not only that the curve was wrong but that it had been published as illustrative and then reprinted 5 times in the same journal and carried into the International Olympic Committee consensus (Soligard et al. 2016) as though it were a validated model. It was never validated.

Three findings against it

  • The thresholds may be an artefact of binning. Wang et al. 2020, Sports Medicine found that once outliers were removed and load was treated as continuous rather than sorted into buckets, the association between the ratio and injury disappeared.
  • The denominator may not matter. Impellizzeri et al. 2020, Sports Medicine 51(3), 581 to 592 showed that a randomly generated chronic load is about as associated with injury as the real one.
  • The metric has known statistical problems. Impellizzeri et al. 2020, International Journal of Sports Physiology and Performance 15(6), 907 sets out why a ratio of two overlapping windows produces artefacts on its own.

So why keep the page. Because the ratio is a real, computable description of your week against your base, and people are going to calculate it either way. This calculator gives the number and says what is known about it. The number is sound; reading a specific injury risk into a specific band is the part that was challenged and has not been re-established.

Frequently asked questions

What is the ACWR and what does it measure?

ACWR (Acute:Chronic Workload Ratio) measures how this week's training load compares to your recent fitness base. Acute load = last 7 days of training. Chronic load = 28-day rolling average divided by 4 (to get a weekly average). ACWR = acute ÷ chronic. A ratio of 1.0 means you trained exactly as much as your average. Above 1.0 is a load spike; below 1.0 is easier than usual.

What is a safe ACWR range?

The bands you will see everywhere are 0.8 to 1.3 as a target, 1.3 to 1.5 as elevated and above 1.5 as high risk, and this calculator shows them because they are what the field uses. They are disputed. The figure they come from, in Gabbett (2016), was the subject of a retraction or errata request to the journal, and a reanalysis treating load as continuous rather than binned found the association with injury disappeared. Read the bands as convention, not as measured risk.

What happens if my ACWR is above 1.5?

It means your last 7 days were more than 1.5 times your average week over the last 28. The often quoted 2 to 4 times higher injury risk traces to the Gabbett (2016) figure, which is the figure a group of researchers asked the journal to retract or correct, so this site does not repeat that multiplier as a finding. What is uncontroversial is that a big jump is a big jump: easing off for 5 to 7 days and letting the base catch up costs little and is what most coaches do.

How do I calculate sRPE (session RPE)?

After each session, ask yourself: how hard was that overall, on a scale of 1 to 10? Multiply that number by the session duration in minutes to get Arbitrary Units (AU). Example: a 45-minute run that felt like a 6 out of 10 = 270 AU. Sum all AUs for the last 7 days to get acute load. Sum the last 28 days and divide by 4 to get the chronic weekly average. That division is a simple rolling average, which is the variant Gabbett used and the one whose thresholds are quoted. The other variant in the literature is an exponentially weighted moving average, which weights recent weeks more heavily; Williams et al. (2017) reported it as the more sensitive of the two. The two give different numbers for the same training diary, so a ratio is only comparable with another ratio computed the same way.

Can I use ACWR for cycling or swimming?

Yes. ACWR works for any endurance sport. For cycling, km or hours are common. For swimming, metres or hours. For sports mixing intensity levels (intervals + easy rides), sRPE × minutes (AU) is more accurate than distance or time alone because it weights intensity. The key is consistency: use the same metric for every session, every week.

How long do I need to track training before ACWR is reliable?

You need at least 4 weeks of consistent data to have a valid chronic baseline. The first few weeks of calculation will be less reliable. After 8 weeks your baseline becomes much more stable. Some coaches recommend a 6-week minimum before making training decisions based on ACWR numbers.

Does ACWR predict injury?

ACWR is associated with injury risk at the group level in research studies, but it does not reliably predict injury for any individual. Many athletes train above ACWR 1.5 without injury; others get injured well within the sweet spot. It is best used as a warning signal. If your ACWR spikes above 1.5, consider recovering rather than adding load, but combine it with subjective feel, sleep quality, and resting heart rate for a fuller picture.