7 tools
Calculators tools
Calculator tools for percentages, compound interest, discounts, ages, aspect ratios, date ranges, and time durations.
Featured calculators
Start with the category pages that carry the most examples, FAQ, and related context.
How to choose
- Choose the calculator that matches the decision first, not the number format.
- Check assumptions such as compounding, sale timing, date boundaries, or aspect-ratio orientation before trusting the result.
- Use the related resource links when the result depends on a rule, limitation, or comparison.
Guides and comparisons
Calculators
Age Calculator
Calculate completed years, months, and days from a birth date to an as-of date.
Calculators
Aspect Ratio Calculator
Resize width or height while preserving the source aspect ratio.
Calculators
Compound Interest Calculator
Calculate compound growth from either a nominal annual rate or a rate applied every eligible day.
Calculators
Date Difference Calculator
Count days between two calendar dates using exclusive or inclusive mode.
Calculators
Discount Calculator
Calculate discount amount and final price from an original price and discount percent.
Calculators
Percentage Calculator
Calculate a percentage of any value with a clear, copyable result.
Calculators
Time Duration Calculator
Calculate hours and minutes between two times, with optional break minutes and overnight mode.