# Recovery Calculators & HIIT Timer | 321 STRONG

> 2 free tools: a recovery time calculator that also gives your soreness timeline, and a HIIT interval timer.

**URL:** https://321strong.com/tools/calculators

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🧮 Calculators · Timers · Data-Driven Recovery
  
# Numbers That Know Your Body
 
Quick tools for the timing questions: when you are ready to train again, when soreness will peak, and how long each interval runs.

   2 Tools   100 % Free   2 Min Avg                ![Recovery Time Calculator illustration](/images/tools/recovery-time-calculator-hero.webp)  
⏱ 2 min         calculators   
## Recovery Time Calculator
  Know when your muscles are ready for the next hard session. 

  Hard training on muscles that have not recovered is how sessions stall. Describe the workout, the muscles, whether it was new to you and your fitness level, and get a recovery time in hours plus when soreness starts, peaks and fades, with a rolling plan for the sore days. 

  What you'd use this for 
- Back-to-back training weeks
- Scheduling leg day around life
- Planning around soreness from new exercises
  [Open Recovery Time Calculator](/tools/recovery-time-calculator)           ![HIIT Recovery Timer illustration](/images/tools/hiit-recovery-timer-hero.webp)  
⏱ Use live         timers   
## HIIT Recovery Timer
  An interval timer that shows the whole session before you start. 

  Work:rest ratios change what a HIIT session trains. Set your work, rest and rounds, see the total time, and let the timer count both phases, calling out work, rest and the last three seconds, with a beep at every change. 

  What you'd use this for 
- Sprint interval sessions
- Circuit training with set rest
- Tabata (20s on, 10s off, 8 rounds)
  [Open HIIT Recovery Timer](/tools/hiit-recovery-timer)         
## Pair the Numbers with the Tool
 
Calculators give you a plan. A 321 STRONG foam roller gives you the tool to carry it out.

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