Heart Rate Zone Calculator vs One Rep Max Calculator
Both tools are 100% free, browser-based, and require no signup. Here is how they differ so you can pick the right one for your task.
Heart Rate Zone Calculator
Free heart rate zone calculator. Enter your age (and optionally resting heart rate) to get your 5 training zones via Karvonen, Tanaka, and 220-age methods — all side-by-side. No signup.
Use HR Zone Calculator →One Rep Max Calculator
Free one rep max calculator. Enter weight lifted and reps to get 1RM estimates from 6 formulas side-by-side (Brzycki, Epley, Lander, Lombardi, Mayhew, O'Conner) plus a full percentage training table. No signup.
Use 1RM Calculator →Feature Comparison
| Feature | HR Zone Calculator | 1RM Calculator |
|---|---|---|
| 5 training zones: recovery, aerobic base, aerobic, threshold, VO2 max | ✓ | — |
| 3 methods side-by-side: 220-age, Tanaka, Karvonen HRR | ✓ | — |
| Resting HR input for personalized Karvonen calculation | ✓ | — |
| Description of what each zone trains | ✓ | — |
| Shareable URL with preset inputs | ✓ | — |
| 100% browser-based | ✓ | — |
| 6 formulas side-by-side: Brzycki, Epley, Lander, Lombardi, Mayhew, O'Conner | — | ✓ |
| Notes on which formula is best for each rep range | — | ✓ |
| Percentage training table from 50–100% of estimated 1RM | — | ✓ |
| Imperial (lb) and metric (kg) input | — | ✓ |
| Shareable URL with preset inputs | — | ✓ |
| 100% browser-based | — | ✓ |
| 100% free — no signup, no watermarks | ✓ | ✓ |
| Browser-based — files never uploaded | ✓ | ✓ |
When to Use Each Tool
- →Your age is used to estimate your maximum heart rate with all three methods.
- →If you know your resting HR (measure lying still after waking), enter it to enable the more personalized Karvonen calculation.
- →See all 5 training zones for all 3 methods side-by-side — bpm ranges and what each zone trains.
- →Input the weight you used for your working set in lbs or kg.
- →Enter how many reps you completed. For best accuracy, use a set of 1–10 reps.
- →See the estimated 1RM from all 6 formulas with notes on which is most reliable for your rep range.
Frequently Asked Questions
Heart rate zones divide your cardiovascular effort into 5 intensity bands, each targeting different physiological adaptations. Zone 1 (50–60% max HR): active recovery, improves blood flow. Zone 2 (60–70%): aerobic base, fat oxidation, mitochondrial development. Zone 3 (70–80%): aerobic conditioning, improves cardiovascular efficiency. Zone 4 (80–90%): lactate threshold, improves sustained high-intensity capacity. Zone 5 (90–100%): VO2 max, maximal aerobic capacity.
The classic 220-age formula is simple but has high individual variability (±10–12 bpm). The Tanaka formula (208 − 0.7 × age) was developed from a larger, more diverse dataset and performs better for older adults. The Karvonen heart rate reserve method is the most personalized — it accounts for your resting HR, reflecting your individual cardiovascular fitness. If you know your resting HR (measure it lying still after waking), use Karvonen.
Your one-rep max is the maximum weight you can lift for exactly one complete repetition with proper form. It is the universal standard for measuring absolute strength in powerlifting and strength training. Direct 1RM testing is accurate but carries injury risk, especially for beginners — calculated estimates from submaximal sets provide a safer alternative.
Accuracy varies by rep range. Brzycki is most accurate for sets of 1–10 reps and is widely used in powerlifting. Epley is reliable for sets of 1–12 reps and is the most common formula used in fitness software. Lander and Mayhew perform well in the 1–10 rep range. All formulas become less accurate above 10–12 reps because fatigue factors increase prediction error. Use the Brzycki or Epley estimate as your primary reference.
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