Acute:Chronic Workload Ratio Calculator
Enter the last four weeks of TSS you actually trained plus the load you have planned for next week. Get your acute:chronic workload ratio, your injury-risk band, and the safe weekly cap that keeps your ramp under the 1.3 guardrail — the same check PaceBeats runs before it commits your week.
Weekly TSS for the last four weeks
Acute:chronic ratio
1.14
Sweet spot · 0.8–1.3
Acute (7-day)
500
last 7 days of TSS
Chronic (weekly avg)
437
28-day weekly average
How to use it
- 1Enter the Training Stress Score you actually completed for each of the last four weeks, oldest week first.
- 2Enter the weekly TSS you have planned for next week.
- 3Read your acute:chronic ratio — acute is your most recent 7 days, chronic is your four-week average.
- 4Check the risk band: green inside 0.8–1.3, amber above 1.3, red above 1.5.
- 5If the planned week is too aggressive, use the safe cap to set a next-week target that keeps your ramp under the guardrail.
Acute load vs chronic load, in one number
Your acute load is the training stress you piled on in the last 7 days. Your chronic load is your 28-day weekly average — the fitness your body has already adapted to. Divide acute by chronic and you get the acute:chronic workload ratio: a single number that tells you whether this week is a normal stimulus or a spike your tissues have not earned. Ride between 0.8 and 1.3 and you are progressing inside your body's tolerance. Cross 1.5 and you are training in the band where injury and illness rates climb sharply.
The guardrail your plan is built against
This is the exact safety check the PaceBeats planner runs before it commits a week. When a proposed ramp would push your ratio past 1.3, the engine throttles the week down to the load your chronic base supports instead of letting you bury yourself in a hero week. The number you read here is the same number that gates your real plan — not a marketing widget bolted on the side.
Why one hero week costs you a season
The danger is rarely the long session itself — it is the size of the jump. A 70 percent ramp from one week to the next loads connective tissue faster than it remodels, and the breakdown lands a week or two later as a niggle that turns into a layoff. Hold your ratio inside the window and you keep stacking fitness; spike it and you trade three sharp weeks for six lost ones. The ratio is how you see the jump before your Achilles does.
How the math works
Acute load is the sum of TSS over the last 7 days. Chronic load is your total TSS over the last 28 days divided by the number of complete weeks in that window — a rolling weekly average rather than a raw four-week total. The ratio is acute ÷ chronic, and the bands follow the workload-ratio research the sport has converged on: 0.8–1.3 is the progression sweet spot, above 1.3 is moderate risk, above 1.5 is the high-risk danger zone. To find the safe cap, the tool solves for the largest next-week TSS that holds the ratio at or below 1.3 — chronic load × 1.3. This mirrors packages/engine/src/safety/acwr.ts exactly, so the ratio and cap you see here are the same values the planner uses to throttle your real build.
Built and reviewed by the PaceBeats coaching-engine team. Every calculator runs the same sports-science math that powers the app's adaptive plans.
Common questions
What is a safe acute:chronic workload ratio?
Keep it between 0.8 and 1.3. That window means this week's load is a normal step up from the fitness you have built, not a spike. Below 0.8 you are detraining — shedding the chronic base that protects you. Above 1.3 is moderate risk, and above 1.5 you are in the danger zone where injury and illness rates rise sharply. Live in the 1.0–1.3 band through a build and let the ratio drop toward 0.8 during a taper.
How do I lower a high ACWR safely?
Do not slam the brakes — a sudden drop tanks your chronic base and leaves you flat. Trim next week's TSS to the safe cap this tool gives you (chronic load × 1.3), then hold that ceiling for a week so your 28-day average catches up. Cut intensity before volume, swap one hard session for an easy aerobic one, and recheck the ratio after the week lands. Two controlled weeks pull a 1.6 back into the green far more reliably than one crash week.
Next step
Turn these numbers into an adaptive plan.
PaceBeats uses this exact math — and your training history — to build and adapt your swim, bike, run, and strength week after week.