Math & Finance
Trying to figure out a tip? Calculate a loan payment? Convert units? These tools handle the math so you don't have to.
Common Problems
How do I calculate a percentage?
What's a good loan interest rate?
How is BMI calculated?
Tools
Age Calculator
Calculate exact age in years, months, and days
BMI Calculator
Calculate Body Mass Index and health category
Percentage Calculator
Calculate percentages, increases, and decreases
Discount Calculator
Calculate sale prices and savings
Loan Calculator
Calculate monthly payments and total interest
Tip Calculator
Calculate tips and split bills
Learn More
Frequently Asked Questions
How do I calculate a percentage?
To find X% of a number, multiply the number by X/100. For example, 15% of 200 = 200 × 0.15 = 30. Our percentage calculator handles all common percentage scenarios.
What's a good loan interest rate?
Interest rates vary by type and market conditions. As of 2026, mortgage rates are typically 5-7%, auto loans 4-8%, and personal loans 6-18%. Always compare rates from multiple lenders.
How is BMI calculated?
BMI = weight (kg) ÷ height (m)². A BMI of 18.5-24.9 is considered normal weight, 25-29.9 is overweight, and 30+ is obese. Note that BMI doesn't account for muscle mass.