Acute Chronic Workload Ratio Calculator
Compare this week's training load with the four week average and see where the ratio falls.
What it does
The acute to chronic workload ratio compares what an athlete has done recently with what they have been used to. The acute side is usually the last 7 days, and the chronic side is usually the average week over the last 28 days. The idea is that a spike relative to the recent base is more informative than a raw weekly total.
Gabbett's 2016 review described the training injury prevention paradox: athletes who carry a well developed chronic load tend to have fewer injuries than athletes who train less, while rapid increases in load are linked with non-contact soft tissue injury. The ratio became a common monitoring tool in team sport because it turns two training totals into a single number that a coach can track.
The most common load measure is session rating of perceived exertion multiplied by duration in minutes, which gives arbitrary units. Distance, sprints, jumps or total minutes also work if the same measure is used every week. Mixing measures, or changing the way load is recorded partway through a block, makes the ratio meaningless because the numerator and denominator no longer describe the same thing.
A ratio from 0.8 to 1.3 is often called the sweet spot. Values below 0.8 suggest the recent week was much lighter than the base, which can happen in a taper or after illness. Values above 1.3 are a caution zone, and values above 1.5 suggest a jump that may be worth spreading out. These bands are training guides, not sharp clinical cutoffs.
The method has limits. A single ratio hides the distribution of load within the week, the number of high speed efforts, sleep, stress and previous injury. Later reviews have questioned how strongly the ratio predicts injury on its own. Use it as one input alongside how the athlete feels, what the week looked like and what the sport demands.
How to use
- Choose one load measure and keep it the same every week.
- Add the load for the last 7 days and enter it as the acute load.
- Add the load for the last 28 days, divide by four, and enter that weekly average as the chronic load.
- Check that both numbers use the same units and the same recording method.
- Read the ratio and the zone.
- Look at the trend across several weeks rather than reacting to one value.
Formula
- Acute load
- Total load in the last 7 days, in arbitrary units or another consistent measure.
- Chronic load
- The 28 day total divided by four, so it is a weekly average.
- Ratio
- A unitless number; 1.0 means the recent week matched the four week average.
If you enter the 28 day total by mistake, the ratio will be about four times too small. Divide the 28 day total by four first, or use a tool that accepts the total and does the division. The ratio can be computed with a rolling 7 day and 28 day window, or with fixed training weeks; pick one method and keep it. A week with no recorded sessions is not the same as a week with zero load, so mark missing data before interpreting a low ratio.
Worked example
Example: 4,200 in the last 7 days against a 3,500 weekly average
Defaults: acute load 4,200 arbitrary units and chronic weekly average 3,500 arbitrary units.
- Divide the acute load by the chronic average: 4,200 / 3,500 = 1.20.
- Compare 1.20 with the 0.8 to 1.3 band.
- It sits inside that band, so the recent week is close to the four week base.
- The ratio is below 1.5, so it is not in the highest zone.
- The tool shows 1.20 and the zone Sweet spot.
Reference table
| Acute to chronic ratio | Zone | How to read it |
|---|---|---|
| Below 0.8 | Low | The recent week was much lighter than the four week base; check for a taper, illness or missing data |
| 0.8 to 1.3 | Sweet spot | The recent week is close to the base that the athlete has been carrying |
| 1.31 to 1.5 | Caution | The load has risen faster than the base; consider spreading the increase |
| Above 1.5 | High | A large jump relative to the base; review the week and the athlete's response |
Limits
- A single ratio hides how load was distributed within the week and the intensity of individual sessions.
- The ratio does not include sleep, stress, previous injury, age or sport specific demands.
- Missing sessions can look like a real drop in load if the data are incomplete.
- Later research has questioned how well the ratio predicts injury on its own, so use it with other monitoring.
Common mistakes
- Entering the 28 day total instead of the weekly average, which makes the ratio about four times too small.
- Changing the load measure from session RPE to distance or minutes partway through the block.
- Treating a low ratio as proof of under training when the athlete simply had a planned recovery week.
- Reacting to one week instead of looking at the trend across several weeks.
- Using the ratio as a stand alone injury predictor rather than one part of the athlete review.
Try it yourself
Quick checks. Answers sit tucked under each question.
A player records 5,000 in the last 7 days and a 4,000 weekly average over 28 days. What is the ratio?
5,000 / 4,000 = 1.25, which is inside the 0.8 to 1.3 sweet spot.
A player records 6,000 in the last 7 days and a 3,500 weekly average. What is the ratio and zone?
6,000 / 3,500 = 1.71, which is above 1.5 and therefore in the high zone.
A player records 2,400 in the last 7 days and a 4,000 weekly average. What is the ratio and zone?
2,400 / 4,000 = 0.60, which is below 0.8 and therefore in the low zone.
Questions
What is the acute chronic workload ratio?
It is the load from the last 7 days divided by the average weekly load from the last 28 days. It compares recent training with the base the athlete has built.
What is a good ACWR?
A common training guide is 0.8 to 1.3. Values above 1.5 raise concern about a rapid increase, while values below 0.8 may reflect a taper, illness or missing data.
How do I measure training load?
Session RPE multiplied by duration in minutes is common. Distance, sprints, jumps and total minutes also work if the same measure is used consistently.
Should I use a rolling window or fixed weeks?
Either can work if it is used consistently. A rolling 7 day and 28 day window is common, but fixed training weeks are easier for team scheduling.
Does a high ratio mean an injury will happen?
No. It is a monitoring signal, not a prediction for an individual. Injury risk depends on many factors, and later research has questioned how much the ratio adds on its own.
What should I do with a ratio above 1.5?
Review the week, the athlete's soreness and sleep, and whether the increase was planned. Spreading the load or adding recovery may be sensible, but the decision belongs with the coaching and medical staff.
Sources
- Gabbett: the training injury prevention paradox, British Journal of Sports Medicine, PubMed
- Windt and Gabbett: the workload injury aetiology model, British Journal of Sports Medicine, PubMed