United Kingdom · 9 tools

Health & Lifestyle calculators

Benchmarks for BMI, calories, heart-rate zones and pace — planning maths, not a diagnosis.

Most used

Start here, then explore the groups below.

BMICalculate your Body Mass Index using height and weight to assess whether you are underweight, healthy, overweight or obese using standard BMI classifications.Health & Lifestyle BMRCalculate your Basal Metabolic Rate to find the calories needed at rest each day. Use BMR to set a calorie target for weight loss, maintenance or muscle gain.Health & Lifestyle CalorieCalculate your daily calorie needs for maintenance, weight loss, or weight gain.Health & Lifestyle Body FatEstimate body fat percentage using waist, hip and neck measurements. Understand your body composition and track progress toward your health and fitness goals.Health & Lifestyle

Use health maths as a benchmark, not a diagnosis

BMI, calories, heart-rate zones and pace tools are input-driven checks. They do not replace clinical advice. Keep units consistent (kg vs lb, km vs miles) and treat zone or calorie outputs as planning ranges.

Confirm the unit system before you enter height, weight or distance.
Use one calculator for the current snapshot (BMI or BMR) and another for the plan (calories, pace, zones).
If a result looks extreme, re-check the inputs rather than changing the target twice.

Snapshot, then the plan

Health calculators translate body measurements into categories and targets that doctors, nutritionists and sports coaches use in their day-to-day practice. The tools in this hub do not diagnose or prescribe — they give you the same starting-point numbers a GP or personal trainer would use when talking to you.

The most-used tools here are BMI and BMR, which sit at the base of almost every health and fitness plan. BMI categorises you on a population-level scale (WHO ranges); BMR estimates the calories your body burns at rest, which is the anchor for building a daily calorie target. Layer on activity level, macro split, and water intake and you have a complete baseline for a personal plan.

Where these tools shine is in forcing specificity. "Eat healthier" is useless as a plan; "consume 2,100 kcal/day with 150g protein" is a target you can measure against. Similarly, "run more" becomes "target 5:30/km pace on easy runs and hit a Zone 3 heart rate of 140-155 bpm during intervals" once you have the pace and heart rate calculators dialled in.

Always treat results as a starting point for conversation with a qualified clinician. BMI in particular doesn't account for muscle mass — athletes often register "overweight" despite low body fat. Use the Body Fat calculator alongside for a more accurate picture. For serious health concerns, these tools are a signal to speak to a GP, not a replacement.