Everyday Tools
Handy region-agnostic utilities — age and date calculators, scientific and statistics calculators, unit conversion, and JSON formatting. All free, no sign-up.
Percent of a number, share of a whole, percent change, and increase/decrease — with formulas.
Tip, total, and per-person share with one-tap percents, bill splitting, and round-up.
Find exact age in years, months, and days between any two dates.
Count days, weeks, and months between two dates, with or without the end date, plus working days.
Add or subtract days, weeks, months, years, or business days from any date.
Working days between dates and business-day deadlines, skipping US or UK public holidays.
What week is it? The current ISO week, the week of any date, and every week of the year.
Weekly hours from clock-in and clock-out times, with breaks, decimal hours, overtime, and gross pay.
Trigonometry, logarithms, powers, and constants for everyday and study use.
Compute mean, median, mode, variance, and standard deviation from a data set.
Convert length, weight, temperature, area, and more across common units.
Format, validate, and diff JSON, plus CSV and YAML conversion — live, with error line markers.
These are the utilities people reach for between the big financial decisions, built with the same care as the finance calculators: every tool shows its formula or method, works in both light and dark mode, and runs entirely in your browser with no sign-up. The percentage calculator handles the four questions people actually ask — percent of a number, share of a whole, percent change, and reverse percentages — each with the formula written out. The tip calculator adds bill splitting and round-up so a group can settle in one step, and the age calculator returns exact years, months, and days between any two dates — the same arithmetic used for eligibility cut-offs and paperwork.
Three date tools cover the questions that come up at work. The days between dates calculator counts the gap between two dates in days, weeks, and months, and lets you choose whether the end date counts. The date calculator finds the date 30, 90, or any number of days, months, or years away, and handles the month-end cases correctly. The business days calculator skips weekends and US federal or UK bank holidays for notice periods, refund windows, and shipping estimates. The week number page shows the current ISO week and every week of the year, and the time card calculator turns a week of clock-in and clock-out times into decimal hours, overtime, and pay.
For study and work there are full scientific and statistics calculators (the latter computes mean, median, mode, variance, and standard deviation from a pasted data set), a unit converter covering length, weight, temperature, area, and volume, and a JSON formatter and validator with clear error positions — handy when a config file breaks and you need to see where. Nothing you enter leaves your device.