# Fitness calculator for Mac, Windows and Linux

Written on 25 October 2026 by Ratio.

Training sums come with units: kilos and pounds, kilometres and miles, minutes and calories. Ratio keeps the units, so the answer says what it is.

## Body

| bmi(80 kg, 180 cm) | 24.7 |
| --- | --- |
| bmr 80 kg 180 cm 30 years male | 1,780 kcal |
| tdee 80 kg 180 cm 30 years male moderate | 2,759 kcal |
| prev - 500 kcal | 2,259 kcal |

BMR uses the Mifflin–St Jeor formula; activity is sedentary, light, moderate, active or very active.

## Heart rate

| hr zones age 30 | Z1 95–114 · Z2 114–133 · Z3 133–152 · Z4 152–171 · Z5 171–190 |
| --- | --- |
| hr zones max 185 | Z1 93–111 · Z2 111–130 · Z3 130–148 · Z4 148–167 · Z5 167–185 |

## Running

| pace 5 km in 27 min | 5:24 /km · 8:41 /mi |
| --- | --- |
| 10 km at 5:30/km | 55:00 |
| race 10 km in 50 min to marathon | 3:50:01 |
| 5 km / 27 min in km/h | 11.11 km/h |
| 42.195 km in mi | 26.22 mi |

Race times use Riegel's formula, the usual estimate for a well-trained runner.

## Lifting

| 3 sets * 8 reps * 60 kg | 1,440 kg |
| --- | --- |
| 165 lb in kg | 74.84 kg |
| 10% of 80 kg | 8 kg |

Percentages work like in the [percentage calculator](https://useratio.app/percentage-calculator).

[Try Ratio free for 7 days](https://useratio.app/download) · $14.99 once, updates included

## Questions

**How do I calculate BMI?** “bmi(80 kg, 180 cm)” or “bmi 80 kg 180 cm”. Hover the answer for the healthy range.

**Can it work out my running pace?** Yes: “pace 5 km in 27 min” gives the pace per kilometre and per mile, and “race 10 km in 50 min to marathon” predicts a finishing time.

**Is this medical advice?** No. Ratio does the arithmetic; what the numbers mean for your health is a question for a professional.

Source: https://useratio.app/fitness-calculator