Online Calculators
Math and health calculations
12 available tools
Proportion Calculator
Calculate the missing value in a proportion A:B = C:X.
BMI Calculator
Calculate body mass index (BMI) and check your weight category.
Weighted Average
Calculate weighted average for grades, scores and other data.
Sleep Calculator
Calculate optimal sleep or wake time based on sleep cycles.
Calorie Calculator
Calculate daily caloric needs based on weight, height, age and activity.
Blood Type Calculator
Calculate the probable blood type of a child based on parents' blood types.
Inflation Calculator
Calculate how inflation affects the value of your money over time.
Dog Years to Human Years
Convert dog age to human years. Takes dog size into account.
Roman Numerals Calculator
Convert Arabic numbers to Roman numerals and vice versa.
Cat Years to Human Years
Convert cat age to human years.
Fuel Consumption Calculator
Calculate fuel consumption and energy usage for combustion and electric vehicles. MPG and L/100km supported.
Electricity Calculator
Calculate the cost of electricity for any appliance. See daily, monthly, and yearly energy costs.
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Online calculators - fast and accurate
Our online calculators let you perform quick, precise calculations without installing any software. Each calculator is optimized for accuracy and ease of use.
BMI calculator
Calculate your body mass index (BMI) by entering your weight and height. The calculator shows your weight category (underweight, normal, overweight, obesity) and result interpretation. Useful for health monitoring and diet planning.
Proportion calculator
Solve proportion equations (a:b = c:x) quickly and accurately. Enter three known values and the calculator finds the fourth. Essential in math, cooking, photography, construction and many other fields.
Weighted average calculator
Calculate weighted average with any number of values and weights. Ideal for school and academic grade averages, exam scores, project grades with different weights. Add and remove rows dynamically.
Frequently asked questions
How is BMI calculated?
BMI = weight (kg) / height (m)². For example, a person weighing 70 kg and 175 cm tall has BMI = 70 / 1.75² = 22.9 (normal range).
What is weighted average?
Weighted average is an average where each value has an assigned weight (importance). For example, an exam grade (weight 3) counts more than a quiz grade (weight 1).
Are the results accurate?
Yes. Our calculators use standard mathematical algorithms with precision to several decimal places.