Use our bikini calculator to find your body shape, waist–hip ratio and curve ratio, then get bikini style ideas that flatter your figure.

Calculate how many helium balloons you need for any weight, plus lift per balloon and helium volume, with this easy online calculator.

Calculate engine RPM, speed, gear ratio & tire diameter with real-time results and unit conversions. Free, fast, mobile-friendly RPM calculator.

Estimate how long a book takes to read. Enter pages, reading speed, and daily minutes to get total time, pages/day, and days to finish.

Free time calculator to add/subtract time, multiply/divide values, and find exact duration between dates and times. Live results with PDF export.

Quickly calculate time between BC and AD years. No year zero rule built-in, with steps, tips, and one-click PDF.

Get your exact age from date of birth in years, months & days, plus weeks and hours. Includes next birthday. Free, fast, mobile-friendly.

Fast Korean age calculator: convert by birth year or current age. Live results, unit switching, PDF report, and step-by-step derivation.

Add hours, minutes, and seconds fast. Free add time calculator that sums multiple entries, supports days to years, and shows instant totals with steps.