Percentage of, percentage change and percentage increase/decrease.
Three calculations in one: X% of Y, percentage change between two values, and add/subtract a percentage from a value.
100% client-side — zero uploads, maximum privacy
Instant results — no waiting for server processing
Secure — your data never leaves your browser
Free to use — no sign-up required
Real-time calculation as you type — no submit button needed
Step-by-step breakdowns for full transparency
Amortization schedules, unit conversions, and health formulas
Bookmarkable results for quick reference
Works offline after initial page load
Calculate discount percentages during shopping comparisons
Compute tip amounts for restaurant bills
Determine percentage change between two values
Calculate markup and margin for product pricing
Find what percentage one number is of another
(New - Old) / Old × 100 — negative results mean a decrease.
Monthly payment, total interest and full amortization schedule.
Length, weight, temperature, data, area, volume, time and speed conversion.
Exact age in years, months, days, plus days until your next birthday.
Days between dates, add/subtract days from a date, weekday lookup.
Convert between decimal, hex, binary and octal with ASCII view.
Body Mass Index with healthy-range guidance.