# Target Heart Rate Calculator

- **URL:** https://codeasystem.com/calculators/fitness/target-heart-rate-calculator/
- **Category:** fitness
- **Description:** Compute Karvonen training zones from your age and resting heart rate, with HRmax estimated by the Tanaka equation.
- **Primary output:** Target HR at 70% intensity (Karvonen): 149 bpm

## Inputs
- Age (name: `age`, type: number, example: 30)
- Resting heart rate (name: `restingHr`, type: number, example: 60)
- Training intensity (name: `intensity`, type: select)

## Outputs
- Target HR at 70% intensity (Karvonen): 149 bpm
- Estimated max HR (Tanaka: 208 − 0.7 × age): 187 bpm
- Heart-rate reserve: 127 bpm

## Formula / methodology
```
HRmax = 208 − 0.7 × age (Tanaka)
THR = (HRmax − HRrest) × %intensity + HRrest
```

Maximum heart rate comes from the Tanaka equation (208 − 0.7 × age), validated as more accurate across ages than the folk-standard 220 − age. The Karvonen method then applies your chosen intensity fraction to heart-rate *reserve*; the span between max and resting; and re-adds resting rate.

Because reserve-based zones account for fitness (lower resting HR widens the reserve), they personalize better than raw percentages of maximum alone.

## Assumptions & limitations
- Morning resting HR measured reliably.
- Tanaka HRmax carries ±10 bpm individual error; zones shift with it.
- Not medical guidance; cardiac patients need clinically determined limits.

## How to use
1. **Measure resting HR**; Count pulses for a full minute upon waking, or read it from a wearable’s overnight average.
2. **Enter age and pick intensity**; Age feeds the Tanaka maximum; the selector highlights your working zone in the table.
3. **Train by feel cross-check**; Zones should match breathing: easy zones allow full conversation, threshold work allows only short phrases.

## Example
At age 30 with a resting rate of 60 bpm, HRmax estimates to 187 bpm and 70%-reserve training lands near 149 bpm, inside the steady-tempo zone.

Result for these inputs:

```
Target HR at 70% intensity (Karvonen): 149 bpm
```

## About this calculator
### Why 208 − 0.7 × age beats 220 − age

Tanaka, Monahan & Seals pooled hundreds of laboratory-measured maxima and found the old 220 rule systematically overshoots for younger adults and undershoots older ones. Their regression halves the typical prediction error and never goes negative.

### What heart-rate reserve adds

Two 40-year-olds share an HRmax estimate but might have resting rates of 45 versus 75. Percentage-of-max zones would hand them identical targets; Karvonen correctly assigns the trained athlete higher absolute training beats.

### Zone cheat sheet

- 50–60%: recovery, fat-oxidation base, fully conversational.
- 70%: steady aerobic work, marathon-effort territory.
- 85%: threshold; sustainable about an hour, phrases only.

## FAQs
### My wearable says my HRmax differs; who wins?

Your measured max from a truly all-out effort beats any equation. Enter it implicitly via zones once known; until then trust Tanaka over 220 − age.

### Do medications affect this?

Beta-blockers suppress both resting and maximum heart rate substantially; cardiac patients must use clinician-prescribed ranges, not formulas.

### Why did the calculator refuse my resting HR?

Resting rate must sit below the estimated maximum to define a positive reserve; otherwise the inputs contradict each other physiologically.

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Last updated: 2026-08-23 · Version: 1.0.0 · [HTML version](https://codeasystem.com/calculators/fitness/target-heart-rate-calculator/)