Simple, practical calculators for BMI, daily calories, water intake and healthy weight planning. Enter your measurements, choose the units you normally use, and get an easy-to-read estimate in seconds.
Calculate BMI using metric or imperial units and see the standard adult BMI reference category, estimated healthy weight range and related measurements.
Estimate basal metabolic rate, maintenance calories and a practical target for maintaining, losing or gaining weight. Results are estimates rather than medical prescriptions.
Estimate a daily fluid target from body weight, activity and climate. Use the result as a planning starting point and adjust for your individual circumstances.
Estimate the adult weight range associated with a BMI of 18.5 to 24.9. This is a general reference range and does not account for every individual's body composition or health status.
BMI, or body mass index, is a screening measure based on height and weight. It is calculated by dividing weight in kilograms by height in metres squared. The standard adult reference categories commonly use 18.5 to 24.9 as the healthy-weight range, 25.0 to 29.9 as overweight, and 30 or above as obesity. These categories are useful for population-level screening, but BMI is not a direct measurement of body fat.
For example, someone with a lot of muscle may have a higher BMI without having the same body-fat level as another person with the same BMI. Age, ethnicity, pregnancy, medical conditions and body composition can also affect how useful a BMI result is. This calculator therefore shows BMI as a general reference rather than a diagnosis.
BMI = weight (kg) ÷ height² (m²)
| Adult BMI | General reference category |
|---|---|
| Below 18.5 | Underweight |
| 18.5–24.9 | Healthy weight |
| 25.0–29.9 | Overweight |
| 30.0 or higher | Obesity |
The calorie calculator estimates basal metabolic rate (BMR) and then uses an activity multiplier to estimate daily energy needs. It uses the Mifflin–St Jeor equation, a commonly used predictive equation for resting energy expenditure. Your actual energy needs can differ because food intake, exercise, sleep, body composition and other factors vary from person to person.
The calculator can show maintenance calories and a moderate target for weight loss or gain. Treat these numbers as a starting estimate rather than a guaranteed result. A gradual approach is generally easier to monitor than making extreme changes based on a single calculation.
Fluid requirements vary considerably. Body size, exercise, temperature, diet, illness, pregnancy and other factors can change how much fluid a person needs. Our calculator uses body weight as a simple starting point and adds an adjustment for exercise and hot conditions. It also converts the estimate into litres, millilitres and approximate glasses.
Water is not the only source of fluid. Foods and other beverages can contribute to total fluid intake as well. If you have been told by a healthcare professional to restrict fluids, use their instructions instead of a generic calculator.
The healthy-weight calculator converts height into an estimated adult weight range corresponding to BMI 18.5–24.9. It can help put a single scale reading into context. It should not be treated as an ideal-weight prescription because a healthy body can fall outside a simple BMI-based range.
For adults, 18.5–24.9 is commonly used as the standard healthy-weight reference range. BMI is a screening measure, not a diagnosis.
Yes. Select Imperial in the BMI calculator and enter height in feet and inches. Weight can be entered in pounds or stone.
No. BMI has limitations and does not directly measure body fat or account for body composition. It is particularly important not to apply adult BMI categories to children and teenagers.
A calorie calculator provides an estimate based on an equation and activity assumptions. Real energy needs can be higher or lower, so changes should be monitored over time.
There is no single amount that fits everyone. Fluid needs depend on body size, activity, temperature, diet and health circumstances. Use this tool as a general planning estimate.
It can provide a general reference range, but it should not be treated as a mandatory target. Body composition and individual health factors matter too.
ToolifyClub Wellness Calculators are designed for simple browser-based estimates. No external API is required for these calculations.