BMI
Body Mass Index = weight (kg) / height (m)². The standard WHO categories are: under 18.5 underweight, 18.5–24.9 normal, 25.0–29.9 overweight, 30+ obesity. BMI is a population-level statistic; it does not distinguish muscle from fat, so very muscular athletes often score "overweight" without being so.
One-rep max
Two common formulas estimate the most you can lift once given the weight and reps you can manage today:
- Epley: 1RM = weight × (1 + reps / 30)
- Brzycki: 1RM = weight × 36 / (37 − reps)
Both are most accurate in the 1–10 rep range. For higher rep counts, the estimate becomes increasingly speculative.
Calories and kilojoules
1 kcal (the "Calorie" on a US food label) = 4.184 kJ (the value on EU and AU labels). A snack labelled 250 kcal contains 1046 kJ.
Marathon pace
A 4-hour marathon is a 5:41/km or 9:09/mile pace. The Boston qualifying time for many age groups is sub-3:30, which is 4:58/km (8:00/mi).