Calculators & Math
Free calculators for math, dates, and percentages. Percentage calculators, date differences, random number generators, and more — instant and private.
Percentage Calculator Online — Free Three percentage calculations in one place: X% of Y, X is what % of Y, and percent change — live results as you type. Free and in-browser. Calculator Online (Arithmetic with Exponents) — Free A clean online calculator for arithmetic with powers, modulo, and parentheses — the result updates as you type. Free, no sign-up, in your browser. Date and Time Difference Calculator Online — Free Calculate the exact time between two dates — days, hours, minutes, and seconds — with live results. Free, in your browser, no sign-up. Add Days, Months, or Years to a Date Online — Free Add or subtract years, months, days, hours, and minutes from any date — with proper month-end handling — and get the exact result. Free, in-browser. Countdown Timer Online to Any Date — Free Count down to any date and time with a live ticking timer — days, hours, minutes, seconds. Free, in your browser, nothing to install. Number Sequence Generator Online — Free Generate a list of numbers from any start with any step — arithmetic sequences up to 10,000 long — and copy the result. Free, in your browser. Filter a List of Numbers Online — Free Keep only the numbers in a range — set a minimum, a maximum, or both — and copy the filtered list. Free, in your browser, nothing uploaded. Sort a List of Numbers Online — Free Sort a list of numbers numerically — ascending or descending — and copy the result. Free, in your browser, nothing uploaded. Min and Max of a Number List Online — Free Find the minimum and maximum of a list of numbers instantly — plus the count — and read the results live. Free, in your browser, nothing uploaded. Average of a List of Numbers Online — Free Calculate the average of a list of numbers — with the sum and count alongside — instantly as you type. Free, in your browser, nothing uploaded. Number Base Converter Online (Binary, Octal, Decimal, Hex) — Free Convert integers between binary, octal, decimal, and hexadecimal — exact even beyond 64-bit sizes. Free, in your browser, nothing uploaded. Roman Numerals Converter Online — Free Convert integers to roman numerals and back — one box, both directions, with canonical-form validation. Free, in your browser, nothing uploaded. Subtract Days, Months, or Years from a Date Online — Free Subtract years, months, days, hours, and minutes from any date — with proper month-end clamping — and get the exact result. Free, in-browser. Unix Timestamp to Date Converter Online — Free Convert Unix timestamps to human-readable dates and back — seconds or milliseconds auto-detected, ISO 8601, RFC 2822, local time. Free, in-browser. Online Stopwatch with Laps — Free A free online stopwatch with lap tracking — start, pause, resume, and record split times, all in your browser. No sign-up, nothing installed. Area Calculator Online — Circle, Rectangle, Triangle — Free Calculate the area of a circle, square, rectangle, triangle, or trapezoid from its dimensions — the result updates as you type. Free, in-browser. Rule of Three Calculator (Direct Proportion) — Free Solve direct-proportion problems — if 3 items cost $6, what do 5 cost? Enter the three values you know and get the fourth. Free, instant, in-browser. Inverse Rule of Three Calculator — Free Solve inverse-proportion problems — if 3 workers take 4 days, how long do 6 take? Enter the three known values and get the fourth. Free, in-browser. Trigonometric Functions Calculator (sin, cos, tan) — Free Compute sin, cos, tan and their inverse functions in degrees or radians — one input, instant result. Free, in your browser, nothing uploaded. Radians to Degrees Converter Online — Free Convert between radians and degrees live as you type — either direction, with full-precision results. Free, in your browser, nothing uploaded. Math Expression Evaluator Online — Free Evaluate arithmetic, powers, roots, trigonometry, constants, and mathjs expressions instantly. Free, private, and loaded only when needed. ETA Calculator from Processing Speed — Free Estimate total duration and completion time from units processed over an elapsed interval. Free, instant, and calculated in your browser. Temperature Converter for 8 Scales — Free Convert temperature live across Celsius, Fahrenheit, Kelvin, Rankine, Delisle, Newton, Réaumur, and Rømer. Free and in-browser. Benchmark Comparison & Statistics Builder — Free Compare benchmark suites by mean, variance, sample count, and speed ratio, then copy a Markdown table. Free and calculated locally. Time Converter — Free Convert seconds, minutes, hours, days, weeks, months, and years — edit any unit and all ten update as you type. Free and in your browser. Length Converter — Free Convert nanometers to miles, inches to centimeters, and every length unit between them — all ten update as you type. Free and in your browser. Area Converter — Free Convert square meters, acres, hectares, and square feet instantly — land measure and floor space in one live grid. Free and in your browser. Weight Converter — Free Convert kilograms, pounds, ounces, grams, and stones — seven units from milligrams to metric tons, updating as you type. Free and in your browser. Volume Converter — Free Convert liters, gallons, cups, and fluid ounces — US measures from milliliters to cubic meters, all updating as you type. Free and in your browser. Speed Converter — Free Convert km/h, mph, knots, meters per second, and feet per second — the speeds of road, air, sea, and science in one view. Free and in your browser. Pressure Converter — Free Convert bar, psi, pascals, atmospheres, and mmHg — tyre pressures, weather readings, and lab units in one live grid. Free and in your browser. Energy Converter — Free Convert joules, calories, kilowatt-hours, and BTU — the energy units of food labels, power bills, and heaters in one grid. Free and in your browser. Currency Converter — Free Convert thirty-plus world currencies at European Central Bank reference rates, fetched fresh by your browser every visit. Free and private. Timezone Converter — Free See what time it is anywhere on Earth for any date and hour — daylight-saving rules handled automatically, in your browser. Free and instant.