Math Tools
Calculator tools for everyday use: BMI calculator, mortgage and loan payment calculators, compound interest projector, percentage calculator, salary converter, unit converter (metric/imperial), statistics calculator (mean, median, mode, standard deviation), and date calculators.
Calculate loan payments, compound interest, tip splits, BMI, and unit conversions in seconds. Each calculator is designed for accuracy with clear output formatting, so you can make informed decisions without spreadsheet setup. Whether you're estimating monthly mortgage payments, comparing investment growth across interest rates, or converting measurements between metric and imperial, these free math utilities give you fast, reliable answers.
Most online calculators are ad-driven widgets that round aggressively. These run the standard formulas — amortization, compound growth, statistics — with the same floating-point precision as a spreadsheet, and they show you the underlying numbers.
Try Compound Interest Calculator first
Project your savings in 30 seconds — the growth table makes compounding visible.
- 1
Enter principal and rate
Set your starting balance and the expected annual return percentage.
- 2
Add monthly contributions
Include deposits to see how contributions compound alongside interest.
- 3
Read the growth table
Year-by-year values show exactly when contributions overtake interest earned.
What Each Tool Does
Loan & Mortgage Calculator
Enter loan amount, interest rate, and term. See monthly payments, total interest paid, and an amortization schedule showing how much goes to principal vs. interest each month.
Compound Interest Calculator
Project investment growth with compound interest. Set principal, annual rate, compounding frequency, and time period. See year-by-year growth in a table.
BMI Calculator
Enter height and weight to get your Body Mass Index with a classification (underweight, normal, overweight, obese) and healthy weight range for your height.
Unit Converter
Convert between metric and imperial for length, weight, temperature, volume, and area. Results update as you type.
Statistics Calculator
Paste a list of numbers and get mean, median, mode, range, standard deviation, variance, and count. Handles comma-separated, space-separated, or one-number-per-line input.
Percentage Calculator
Calculate what percent X is of Y, find X% of Y, or determine the percent increase/decrease between two values.
Real Ways People Use These
Comparing Loan Offers
You have two mortgage offers with different rates and terms. Plug both into the loan calculator to see which one costs less in total interest over the life of the loan.
Planning Retirement Savings
You want to know how much your savings will grow in 20 years. Use the compound interest calculator with your current balance, expected return rate, and monthly contributions.
Converting Units for a Recipe
A recipe lists ingredients in grams but your kitchen scale uses ounces. The unit converter gives you the exact conversion instantly.
Analyzing Survey Data
You collected 50 responses with numerical ratings. Paste them into the statistics calculator to find the average, median, and standard deviation.
Pick the right tool for the job
Four common scenarios and the tool that handles each one.
| When you need to… | Use | Why |
|---|---|---|
| Compare two loan offers | Loan Calculator | Monthly payment plus total interest over the life of the loan. |
| Check your body mass index | BMI Calculator | Classification plus a healthy weight range for your height. |
| Convert a recipe's units | Unit Converter | Metric and imperial for length, weight, volume, and temperature. |
| Summarize a set of survey ratings | Statistics Calculator | Mean, median, mode, and standard deviation from pasted numbers. |
Getting the most out of these tools
Compound interest rewards early deposits
Run the calculator with a small monthly contribution — the growth table makes the case for starting now, not later.
Compare APRs, not just payments
Two loans with the same monthly payment can differ by thousands in total interest over the term.
Use the median for skewed data
For income or ratings, the median resists outliers far better than the average.
How it works
Calculations use JavaScript's Number type (IEEE 754 double-precision floating point) with configurable decimal places. The same arithmetic precision used by Excel and Google Sheets.