Build Your Interval Session
Suggested MET values: light 5 to 6, moderate 7 to 9, intense 10 to 12, very intense 13 or higher.
Example Data Table
| Input | Example Value | Why It Matters |
|---|---|---|
| Prep Countdown | 10 sec | Gives time to assume position before the timer begins. |
| Warm-up | 300 sec | Prepares muscles and joints before intense efforts. |
| Work Interval | 40 sec | Defines how long each high effort phase lasts. |
| Rest Interval | 20 sec | Controls short recovery between work rounds. |
| Rounds Per Set | 8 | Determines repeated effort cycles within one set. |
| Sets | 3 | Extends the full workout structure across multiple blocks. |
| Rest Between Sets | 90 sec | Allows deeper recovery before the next set begins. |
| Cooldown | 300 sec | Supports gradual recovery after the final effort. |
| Weight and MET | 70 kg and 10 MET | Used to estimate calorie expenditure across the session. |
Formula Used
Rest Periods = Rounds − 1, unless final round rest is enabled.
Time Per Set = (Rounds × Work Interval) + (Rest Periods × Rest Interval)
Total Time = Prep + Warm-up + (Sets × Time Per Set) + ((Sets − 1) × Set Rest) + Cooldown
Duty Cycle % = Work Interval ÷ (Work Interval + Rest Interval) × 100
Calories = MET × Body Weight in kg × Session Duration in Hours
These formulas help you plan not only the training clock, but also the true distribution of effort, recovery, and total workout commitment.
How to Use This Calculator
- Enter a session name so your exported files stay organized.
- Set the prep countdown, warm-up, and cooldown in seconds.
- Define your work interval and rest interval lengths.
- Choose how many rounds appear inside each set.
- Enter the number of sets and the rest time between sets.
- Add body weight and MET value if you want a calorie estimate.
- Select whether the last round in each set should also include rest.
- Press Calculate Timer to see the session summary, schedule table, timeline graph, and export buttons.
Frequently Asked Questions
1) What does this interval training timer calculator do?
It builds a full timed workout using your prep, warm-up, work, rest, sets, and cooldown values. It also summarizes total time, work time, recovery time, estimated calories, and a detailed schedule.
2) Can I use this for HIIT, boxing, cycling, or circuit sessions?
Yes. Any workout that alternates effort and recovery can fit this tool. You can adapt it for sprint intervals, bodyweight circuits, bag rounds, rowing sessions, bike repeats, and similar formats.
3) Why is rest after the last round optional?
Some coaches finish a set immediately after the final effort. Others prefer a short recovery before moving to set rest or cooldown. The option lets the session clock match your exact programming style.
4) What is the work to rest ratio?
It compares effort time with recovery time inside a round. A higher ratio usually means denser, tougher sessions. A lower ratio usually provides more recovery and often supports repeatable power output.
5) How is calorie burn estimated here?
The estimate uses the MET method: MET multiplied by body weight and workout duration in hours. It provides a planning estimate, not a medical or device-grade measurement.
6) Why should I include warm-up and cooldown?
They improve the realism of the schedule. A workout is rarely only work and rest rounds. Warm-up and cooldown also affect total time, pacing, and estimated calorie burn.
7) What does the Plotly timeline show?
The chart places each phase on a time axis so you can see exactly when every work round, rest period, set recovery, warm-up, and cooldown occurs during the session.
8) What do the CSV and PDF exports include?
The CSV export saves the summary metrics and the full schedule table. The PDF export captures the visible results section so you can keep a shareable training snapshot.