Acute:chronic workload ratio calculator
ACWR divides your last 7 days of training load by your average weekly load over the last 28 days. Values between 0.80 and 1.30 are the commonly cited sweet spot associated with the lowest relative injury risk; above 1.50 indicates a spike associated with the highest risk. Enter your numbers below.
Chronic (weekly average): 28.5
1.05
Sweet spot — lowest relative injury risk
Reading the bands
| ACWR | Interpretation |
|---|---|
| Below 0.80 | Undertrained relative to your own baseline; higher relative injury risk on return |
| 0.80 – 1.30 | Sweet spot — lowest relative injury risk |
| 1.30 – 1.50 | Elevated; you are ramping faster than your body has adapted to |
| Above 1.50 | Load spike; highest relative injury risk |
A worked example
An athlete runs 30km in the last 7 days. Over the previous 28 days they averaged 28.5km per week. ACWR is 30 ÷ 28.5 = 1.05 — comfortably in the sweet spot.
Now suppose the same athlete jumps to 50km in a week. ACWR becomes 50 ÷ 28.5 = 1.75 — a spike, and precisely the pattern the ratio exists to catch.
What the ratio is actually telling you
ACWR is a rate-of-change measure, not an absolute one. A high chronic workload is protective; a sudden increase is what carries risk. Two runners can both be at 50km this week, and the one who has been building for months is in a completely different position from the one who ran 20km last week.
This is also why the ratio punishes returning from injury or holiday: your chronic load has decayed, so ordinary training reads as a spike. That is a feature — it is the period when people most often get hurt.
The ratio has real critics. The original research has acknowledged methodological limitations, and the exact thresholds are contested. Use it as a signal about how fast you are ramping, not as a prediction.
Track your ACWR automatically
Body Vitals computes acute:chronic workload ratio from Apple Health alongside readiness, Zone 2 minutes and training load — no manual entry.
View on the App StoreFrequently asked questions
What is a good acute:chronic workload ratio?
Between 0.80 and 1.30 is the range usually described as the sweet spot, associated with the lowest relative injury risk. Below 0.80 suggests undertraining and a detrained state; above 1.50 indicates a load spike associated with the highest relative injury risk.
How do you calculate ACWR?
Divide the acute workload — total training load over the last 7 days — by the chronic workload, which is the average weekly load over the last 28 days. For example, 30km run this week against a 28.5km four-week average gives an ACWR of 1.05.
What counts as training load?
Any consistent measure works as long as you use the same one throughout: distance, duration, session RPE multiplied by minutes, or a device-computed load score. The ratio compares your recent load to your own baseline, so the unit matters less than the consistency.
Is ACWR scientifically reliable?
It is widely used in professional sport but has been legitimately criticised — the original studies have known methodological limitations and the specific thresholds are debated. Treat it as one useful signal about the rate of change in your training, not a precise injury predictor.