Track intensity with heart rate, duration, and effort. See zones, TRIMP score, calories, and strain. Save sessions, export reports, and progress toward stronger workouts.
Enter your details and session metrics. The layout adapts: 3 columns on large screens, 2 on tablets, 1 on mobile.
These sample sessions show how intensity changes with heart rate, duration, and perceived effort.
| Workout | Duration (min) | Avg HR (bpm) | RPE | Estimated Zone | Notes |
|---|---|---|---|---|---|
| Easy Run | 35 | 128 | 4 | Endurance | Builds aerobic base with low strain. |
| Tempo Ride | 50 | 152 | 6 | Tempo | Sustained effort, improves pace endurance. |
| Interval Session | 30 | 168 | 8 | Threshold | Higher load; allow recovery afterward. |
Note: Heart-rate devices can drift during intervals. For HIIT, consider using a smoothed average or steady-state segments.
Workout intensity is the bridge between effort and adaptation. This calculator converts heart-rate and perceived effort into consistent scores, so training weeks can be compared fairly across the month. When intensity is measured, you can avoid stacking hard days, protect recovery, and still progress. The result panel highlights intensity zone, %HRmax, and %HRR to show how demanding the session was relative to your own capacity.
Max heart rate can be estimated with Tanaka, Classic, or a female-specific option, because one formula rarely fits everyone. From MaxHR and RestHR the tool derives Heart-Rate Reserve, then computes %HRR using the Karvonen approach. %HRR typically aligns better with effort than %HRmax because it accounts for individual resting differences. These metrics help interpret easy aerobic work versus threshold or high-intensity work.
To quantify load, the calculator provides TRIMP and Session Load. TRIMP weights time by fractional %HRR using an exponential factor, reflecting the higher physiological cost of harder work. Session Load uses the Foster model: RPE multiplied by duration. This pairing is useful because heart-rate may be lower in hot weather, dehydration, or heavy lifting, while RPE still captures overall strain.
Energy estimates are included using heart-rate based equations that use age, weight, and average heart rate. Calories are not a performance score, but they support fueling and weight-management planning. For comparisons, focus first on intensity zone and composite intensity score, then review calories and duration. A 30‑minute high zone session can be more stressful than a 60‑minute low zone session, even if calories look similar.
Saving sessions creates a simple training diary with export options. Review weekly totals of Session Load or TRIMP to apply gradual increases, often 5–10% per week for many athletes. Use the zone label to balance easy, moderate, and hard work, and watch for spikes after travel or poor sleep. If intensity remains high while performance stalls, prioritize recovery or reduce duration before raising effort again.
Use a recent resting heart rate, a realistic average heart rate for the session, and a duration that excludes long breaks. Pair those with an honest RPE. If your device spikes during intervals, prefer a smoothed average.
%HRR usually reflects effort better because it adjusts for your resting heart rate. %HRmax is still useful for quick checks. When they disagree, rely on %HRR and your RPE to interpret the session.
TRIMP emphasizes cardiovascular stress and rises sharply at higher intensity. Session Load captures overall strain, including heat, hills, or resistance work, because it is based on RPE. Tracking both gives a balanced view.
Yes. For HIIT, use an average heart rate that represents the full session, not only peaks. For strength training, heart rate may understate effort, so Session Load and RPE become more informative than TRIMP.
Increase gradually when you are recovering well. A common approach is a 5–10% rise in weekly Session Load or TRIMP, then a lighter week every three to five weeks. Use fatigue, sleep, and soreness as checks.
It is a helpful estimate, not a lab measurement. Hydration, temperature, and sensor error can shift values. Use calories to guide rough fueling targets, then adjust using body weight trends and training performance.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.