Training Load Acute:Chronic Ratio (ACWR)

AC:WR = 7-day training load / 28-day average. Sweet spot 0.8-1.3; >1.5 raises injury risk.

Inputs

Sum your weekly TSS, mileage, lifting tonnage, or RPE×duration.

Sum of last 28 days ÷ 4.

Result

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General calculation reads

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How to use this calculator

  • Track a load metric daily for ≥4 weeks.
  • Sum last 7 days = acute.
  • Sum last 28 days ÷ 4 = chronic.
  • Aim for AC:WR 0.8-1.3.

About this calculator

The Acute:Chronic Workload Ratio (Gabbett 2016) compares the past 7 days of training to the rolling 28-day average. Ratio between 0.8-1.3 = "sweet spot" with the lowest injury risk. >1.5 ("spike") is associated with 2-4× the soft-tissue injury rate in team sports. <0.8 means undertraining or detraining — safe but slower adaptation. Use any consistent load metric: cycling TSS, running mileage, RPE × minutes, or lifting tonnage. Recalculate weekly.

Frequently asked

What load metric?+
Anything consistent: TSS, mileage, RPE × duration, swim yardage, lifting tonnage. Don't mix metrics within the same calculation.
Original research?+
Tim Gabbett and team published the ratio in rugby and Australian football, then it spread to running and cycling. Subsequent replication is mixed but the directional advice holds.
How fast can I ramp?+
5-10% week-over-week is the rule. A 50% jump for one week (AC:WR ~1.5) is when risk spikes.
Tapers?+
During a 2-3 week pre-race taper, AC:WR drops to ~0.6-0.7. That's fine; you're not getting injured at low loads, just losing fitness.
How does this differ from Banister TSB?+
TSB (Training Stress Balance) uses exponential decay; AC:WR uses simple windows. Functionally similar — both warn against spikes after long calm.

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