Free calculators. Clear answers. No sign-up.
Check your BMI, find your daily calories, and plan your next step in seconds.
How many calories do you need each day, and is your weight in a healthy range? Those two questions sit behind almost every diet plan, and most people guess at the answers. Weight Insider gives you the numbers instead. Our free calculators work out your BMI, your resting calorie burn, your total daily burn, and your ideal weight in seconds, using the same standard formulas that doctors and health organisations use. You enter your height, weight, age and activity level, and you get a clear result with a plain explanation of what it means.
Every tool on this page is free to use, works instantly in your browser, and needs no sign-up or download. Start with the BMI calculator below if you want a quick check, then find your daily calorie target with the BMR and TDEE calculators. If you are trying to lose weight, gain weight in a healthy way, or simply hold steady, the start-here paths further down this page point you to the right tool and the right guide for your goal.
The calculators give estimates, not medical measurements. They are a starting point for planning food, movement and sleep, and they work best when you test your number for a few weeks and adjust it. If you have a health condition, are taking medication, or are pregnant, talk to a healthcare professional before you change your diet or exercise routine.
How to use this calculator
- Choose metric or imperial units, whichever you are more comfortable with.
- Enter your height and weight, and select your gender.
- Click Calculate BMI to see your result, your category, and your healthy weight range.
What your result means
The four BMI categories are a general guide for adults. A single number cannot measure muscle, bone density, body fat, age, or body shape, so use your category as a starting point, not a final answer.
| Category | BMI range |
|---|---|
| Underweight | Below 18.5 |
| Healthy weight | 18.5 to 24.9 |
| Overweight | 25 to 29.9 |
| Obesity | 30 or above |
Most used calculators
These are the tools visitors open most. Each one is free, works in seconds, and needs no sign-up.
All 27 free tools
Every calculator below is free to use, works instantly in your browser, and needs no sign-up or download.
Weight and body
Determine your BMI based on height and weight.
Find how many calories your body burns at rest each day.
Calculate your total daily calorie needs based on your activity level.
Calculate your ideal weight based on various factors.
Estimate your body fat percentage from simple measurements.
Work out how much of your weight is lean muscle and tissue.
Calculate your waist-to-hip ratio for health assessment.
Set and track your weight loss goals effectively.
Easily convert between different weight and mass units.
Quickly convert between various length units.
Calories and nutrition
Calculate daily calorie needs based on your activity level.
Estimate calories burned during various physical activities.
Calculate your macro intake based on your dietary preferences and goals.
Split your daily calories into the right balance of carbs, protein and fat.
Find how much protein you need each day for your goals.
Look up the glycemic index of foods to manage blood sugar.
See if you are getting enough fiber in your daily diet.
Check for signs of common vitamin and mineral deficiencies.
Calculate your recommended daily water intake for hydration.
Check whether you are drinking enough water each day.
Health, activity and sleep
Generate personalized exercise routines tailored to your goals.
Assess how active you are and what it means for your calories.
Discover your metabolic age compared with your actual age.
Find your target heart rate zones for training.
Measure your current stress level in a few quick questions.
Find the best times to wake up based on your sleep cycles.
Assess the quality of your sleep and how to improve it.
See all tools with more detail on the Weight and Wellness Tools page.
Start here
Pick your goal and follow the path. Each one pairs the right calculator with a guide that explains the numbers in plain language.
Lose weight
Start with the TDEE calculator to find your daily calorie target, then set your goal with the weight loss goal calculator. Small, steady changes work best, and a daily deficit of about 400 to 500 calories is a realistic place to begin.
TDEE Calculator | Weight Loss Goal Calculator
Read the guide: BMR and TDEE Explained: How Many Calories You Really Need
Gain weight
Start with the BMI and TDEE calculators to find where you are now and how many calories you need to add. Healthy weight gain is steady, built on enough protein and strength training, not on junk food.
BMI Calculator | TDEE Calculator
Read the guide: Weight and Wellness Tools
Maintain your weight
Start with the TDEE calculator to find your maintenance calories, then check your progress with the BMI calculator. If your weight is steady and your energy is good, you are on target.
TDEE Calculator | BMI Calculator
Read the guide: BMR and TDEE Explained: How Many Calories You Really Need
How our calculators work
We use standard formulas that health professionals rely on, and we show our workings so you can trust the numbers. The BMI calculator divides weight in kilograms by height in metres squared, with the healthy range set at 18.5 to 24.9. The BMR and TDEE calculators use the Harris-Benedict Revised formula, which estimates resting calorie burn from your sex, age, height and weight, then applies an activity multiplier from 1.2 for a sedentary day to 1.9 for very active work and training. The ideal weight calculator uses the Devine formula, which gives a target weight for your height. The glycemic index calculator is a food lookup that shows how quickly a food raises blood sugar, so you can compare foods side by side.
These formulas give estimates for a typical adult. Real calorie needs vary with muscle, age, health and daily routine, so if your results and your actual progress disagree, trust the progress you can measure and adjust your target from there.
Medical disclaimer
The content and calculators on this page are general information only and are not medical advice. They cannot diagnose or treat any condition, and they do not replace advice from a doctor, dietitian or other qualified healthcare professional. If you have a health condition, are taking medication, are pregnant, or are under 18, talk to a healthcare professional before changing your diet, exercise routine or weight. If you are concerned about your weight or your health, please seek professional help.
Latest guides
Practical guides that explain the numbers, so you can use them with confidence.
BMR and TDEE Explained: How Many Calories You Really Need
Learn what BMR and TDEE mean, how they are worked out, and how to use them to plan your daily calories.
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Best Weight Loss Programs and Services in O’Fallon, Missouri
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Weight Loss in Jacksonville, FL: A Guide to Achieving Your Health Goals
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Weight Loss Gummies for Women: An Effective and Tasty Solution
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Sports and Fitness
How movement and sport support a healthy weight, from getting started to staying consistent.
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Frequently asked questions
Are the calculators free to use?
Yes. Every calculator on this page is completely free, works instantly in your browser, and needs no sign-up, account or download.
How do I know which calculator to start with?
Start with the BMI calculator if you want a quick check of your weight category. Then use the BMR and TDEE calculators to find how many calories you burn each day, which is the number you need to plan food and exercise.
What is the difference between BMR and TDEE?
BMR is the number of calories your body burns at rest, just to keep you alive. TDEE adds your daily movement and exercise to that number, so it is your total daily calorie need.
Are the results medical advice?
No. The calculators give estimates based on standard formulas, and they are general information only. They do not diagnose, treat or replace professional advice. If you have a health condition or are taking medication, talk to a healthcare professional before changing your diet or exercise routine.
Do I need to create an account or give my email?
No. The calculators run entirely in your browser, and nothing you enter is sent to us or stored. If you want a full PDF report for a calculator, the calculator page itself offers the download.
Weight Insider gives you free calculators and practical guides to help you reach and keep a healthy weight. Everything on this page is written for real people, in plain language, and reviewed against standard health guidance.