| What it does | Free Karvonen formula heart rate zone calculator
| Date, deadline and time calculators with visible assumptions and sources
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| Stage | Established
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| Founded | Not given
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| Based in | Not given
| US
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| Pricing model | Free
| Free
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| Pricing | Not given
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| Key features | - Five personalized training zones based on heart rate reserve
- Accounts for resting heart rate and cardiovascular fitness
- Custom maximum heart rate input from multiple formulas
- No signup required, runs entirely in browser
- Weekly resting heart rate logging and progress tracking
- Zone-specific training guidance for different goals
- Shareable and printable zone results
- Embeddable calculator widget for websites
| - 184 calculators across 53 categories
- Shows counting rules and assumptions with each result
- Local-first processing with no data sent to servers
- Holiday and weekend calendar selection
- Business day counting
- Date arithmetic (add or subtract days, weeks, months, years)
- Sleep cycle planner with NIH-based 80-100 minute cycles
- Time zone conversion with DST handling
- Save results as images or add to calendar
- Schengen visa 90/180 day rolling window auditing
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| What makes it different | - More accurate than age-only formulas, accounting for individual cardiovascular fitness
- Zones adapt as your fitness improves and resting heart rate drops
- Based on 1957 Karvonen research used by coaches and sports scientists
- Independent, no data collection or external servers
- No ads inside the calculator, free to use with optional embedding
| - Shows the source and counting rule beside every answer
- No sign-up or account required to use any calculator
- All inputs stay in your browser for privacy
- Comprehensive coverage across 53 life and work categories
- Higher-risk calculators include prompts to verify with professionals
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| Community votes | 0 | 0 |
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| DR (Domain Rating by Ahrefs) | 11 ● no change since last check | Not checked yet ● no change since last check |
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| Trust Flow (Majestic) | 19 | 0 |
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| Citation Flow (Majestic) | 25 | 0 |
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| Referring domains (Majestic) | 40 | 0 |
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CalculateMyHeartRate
CalcSpan