Rest Day / Recovery Calculator

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

Result

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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.