ACWR calculator: is your training load increasing too quickly?
ACWR compares the current week’s load with the average of the previous four weeks. It answers a key amateur-athlete question: have I increased training too abruptly? Enter kilometres, hours or TSS for five weeks to see your ratio, risk zone and next week’s target range.
Enter weekly load in any unit — kilometres, hours or TSS — but use the same unit for every week.
Complete all five fields and the result will appear automatically. Chronic load must be greater than zero.
ACWR in plain English
The body adapts to training over weeks and months. ACWR compares what you did this week, your acute load, with what your body has become accustomed to over the past month, your chronic load. A ratio around 1 indicates stable load. Above 1.3, training may be progressing faster than muscles, tendons and ligaments can adapt.
Tim Gabbett popularised the method in team sports in 2016, but it is also useful in endurance sports including running, cross-country skiing, cycling and triathlon. Use kilometres, hours or TSS, provided you use the same unit throughout.
How to interpret the ratio
- Below 0.8 — load is below your norm: a deload or time off. Appropriate after a race, but sustaining it beyond a week or two leads to detraining.
- 0.8–1.3 — the commonly cited optimal range: productive progression with lower risk. Research associates this range with the lowest injury incidence.
- 1.3–1.5 — caution: one such week may be acceptable during a training camp or hill block, but consecutive weeks at this level are not advisable.
- Above 1.5 — a sharp spike with the highest injury and overtraining risk. A typical example is returning after two sedentary weeks and immediately resuming your previous volume.
Rules to use alongside ACWR
- Increase load by no more than 5–10% per week — the traditional 10% rule roughly corresponds to an ACWR of 1.1 and remains a useful amateur guideline.
- Make every third or fourth week a deload: reduce volume by 30–40%, producing an ACWR around 0.6–0.7. Adaptation occurs during recovery.
- After a break, resume at roughly half your habitual volume and add 10–15% per week, even if you feel excellent.
- ACWR is a guide, not a diagnosis: it does not see sleep, stress or how you feel. Learn more in the easy-volume guide and our analysis of the Norwegian method.
FAQ
Which unit should I use for training load?
Any unit, provided it remains consistent: kilometres for running, hours for cross-country skiing and triathlon, or TSS for power-based training. For a mixed week of running, gym work and cycling, hours or TSS combine different activities most conveniently.
How is this different from my watch metrics?
Garmin and COROS display related metrics such as Training Load Focus and load ratio, but their algorithms are proprietary. This calculator uses the open Gabbett formula: acute week divided by the four-week average. SkolCoach uses a more responsive EWMA 7/42-day variant, as in intervals.icu and TrainingPeaks, calibrated to your history.
Does ACWR 1.6 mean I will definitely get injured?
No. ACWR describes a statistical association, not an individual prediction. It indicates that the rate of progression may be risky for a typical athlete. Sleep, stress, injury history and strength training all modify individual risk. Treat the red zone as a prompt to slow down and assess how you feel, not a diagnosis.
What if I have just started training?
Initially, chronic load is close to zero and the ratio becomes unhelpfully high. For the first 4–6 weeks, simply progress gradually by around 10–15% per week. Start monitoring ACWR once you have approximately a month of history.
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