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Health & Lifestyle calculators

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

9 tools for United Kingdom

BMICalculate your Body Mass Index using height and weight to assess whether you are underweight, healthy, overweight or obese using standard BMI classifications.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.CalorieCalculate your daily calorie needs for maintenance, weight loss, or weight gain.Body FatEstimate body fat percentage using waist, hip and neck measurements. Understand your body composition and track progress toward your health and fitness goals.Macros SplitCalculate your daily macronutrient split of protein, carbohydrates and fat based on your calorie goal. Plan your diet to support weight loss or muscle gain.Ideal WeightCalculate your ideal weight range based on height and healthy BMI. Find your target weight.

Body composition4

The core assessment tools — BMI for category, BMR for resting burn, body-fat and ideal-weight for nuance.

BMICalculate your Body Mass Index using height and weight to assess whether you are underweight, healthy, overweight or obese using standard BMI classifications.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.Body FatEstimate body fat percentage using waist, hip and neck measurements. Understand your body composition and track progress toward your health and fitness goals.Ideal WeightCalculate your ideal weight range based on height and healthy BMI. Find your target weight.

Nutrition planning3

Daily calorie targets, macro splits, and hydration — the building blocks of any serious nutrition plan.

CalorieCalculate your daily calorie needs for maintenance, weight loss, or weight gain.Macros SplitCalculate your daily macronutrient split of protein, carbohydrates and fat based on your calorie goal. Plan your diet to support weight loss or muscle gain.Water IntakeCalculate your recommended daily water intake based on weight and activity level.

Training and performance2

For runners and gym-goers: heart-rate training zones and target running pace.

Heart Rate ZoneCalculate personalised heart rate training zones using the Karvonen method. Find your fat burn and aerobic zones.Running PaceCalculate running pace per km and per mile from your distance and time. Convert between pace and speed.

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.

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.

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

Guides that support this category

Use these when you need more context before choosing a calculator.

BMI vs Body Fat Calculator: Which Is Better for Tracking Fitness?

Compare BMI and body fat percentage methods to find the best way to track your fitness progress.

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