Rest Day / Recovery Calculator

Recommended rest days = base + intensity adjustment − sleep credit + age adjustment.

Inputs

Result

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General calculation reads

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How to use this calculator

  • Pick honest intensity of last session.
  • Enter average sleep over the last 3 nights.
  • Enter age.
  • Use as a guideline, not absolute — your body knows.

About this calculator

Recovery is highly individual but follows patterns: easy aerobic work needs little, max efforts need 48-72 hours. Sleep is the single biggest modifier — 8+ hours doubles recovery rate vs. <6. Age matters too: 40+ year-olds typically need 25-50% more rest between hard sessions. This calculator gives a starting estimate; track your own response (HRV, soreness, performance the next day) to dial in.

Frequently asked

Hard session every day OK?+
For elites with months of base, possibly. For most: 2-3 hard sessions / week max. Easy days between are required for adaptation.
How does HRV factor in?+
Low morning HRV vs. baseline = under-recovered. Add a rest day. Apps (Whoop, Garmin, Elite HRV) give a green/red read.
Active recovery vs. full rest?+
For aerobic work: easy active recovery (Z1 spin, walk) often beats total rest. For lifting: total rest of trained muscles, but cardio elsewhere is fine.
Why does sleep dominate?+
Most muscle protein synthesis and HGH release happen during deep sleep. Sleep-deprived training adapts ~30% slower at the same load.
How does this compare to AC:WR?+
AC:WR (training-load-acwr) operates at the weekly level; this is per-session. Use both — AC:WR for trends, this for tomorrow's decision.

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