Online Calculator
A free, no-fuss calculator. Click the keys or type on your keyboard. Every answer goes on the tape so you can reuse it.
All tools
Everything runs in your browser. Nothing you type is sent anywhere.Conversion Calculators
Convert units effortlessly. Pick a category or jump straight to a popular conversion.Timers, clocks and pickers
Scientific Calculator
Trigonometry, logarithms, powers, roots and factorials. Switch between degrees and radians with the DEG key.
Tip: you can type a full expression such as 2^10 or (3+4)*5. Missing closing brackets are added for you. log is base 10 and ln is base e.
Percentage Calculator
Four common percentage questions. Fill in the blanks and the answer updates as you type.
Circle Tools
Enter a radius, diameter, circumference or area and get the rest. The answers update as you type.
r = d ÷ 2 · C = 2πr · A = πr². Pick a unit to label the answers. Area is shown in that unit squared.
BMI Calculator
Body Mass Index is your weight in kilograms divided by your height in metres squared. It is a quick screening number for adults, not a diagnosis.
Adult categories (WHO): under 18.5 underweight · 18.5–24.9 healthy · 25–29.9 overweight · 30 and above obese. BMI does not account for muscle mass, age, sex or ethnicity, so talk to a clinician about your own health.
Age Calculator
Find an exact age in years, months and days on any date.
Tip & Bill Splitter
Add a tip to a bill and split it evenly.
Loan Calculator
Estimate the monthly payment on a fixed-rate loan and see how the balance falls each year.
Total paid:
Year-by-year
| Year | Principal paid | Interest paid | Balance left |
|---|
Uses the standard amortization formula M = P·r(1+r)ⁿ ÷ ((1+r)ⁿ − 1), where r is the monthly rate and n the number of months. Real loans may add fees.
Unit Converter
Pick a category, type a value, and see it in every unit at once.
In every unit
Volume Calculator
Volume and surface area of common 3D shapes.
Use any one unit for every side. The volume is in that unit cubed. 1 m³ = 1,000 litres.
Maths Calculator
Type a full sum and press Enter. Supports + − × ÷, powers (^), brackets, sqrt, sin, cos, tan (degrees), log, ln, abs, round, floor, ceil, pi and e.
Tip: use % for remainder, for example 17 % 5 gives 2. Answers are rounded to 10 decimal places.
Online Abacus
Slide the beads to the right to count. Each rod holds ten beads, and five rods count up to 50.
Tap a bead to move it and every bead between it and the edge. Tapping a counted bead moves it back.
Darts Checkout Calculator
Enter the score you have left. The calculator lists the best ways to finish on a double with three darts or fewer.
Checkout
S = single, D = double, T = treble, Bull = 50. 25 is the outer bull. You must finish on a double.
Patio Calculator
Work out how many slabs you need, with an allowance for cuts and breakages, and how much sub-base to order.
Sub-base weight assumes compacted crushed stone at about 1.9 tonnes per cubic metre. Treat all figures as estimates and check with your supplier.
Ring Size Converter
Convert a ring size between US, UK, EU and Japan, or start from the measurements of your finger or an existing ring.
Sizes are approximate and brands differ by up to half a size. Wrap a strip of paper around the base of your finger, mark where it overlaps, and measure the length for the circumference.
Size chart
| US | UK | EU | Japan | Diameter |
|---|
The History of the Calculator
People have built machines to do arithmetic for thousands of years.
- c. 2400 BCE · The abacus. Counting boards and the first abaci appear in Mesopotamia and spread across the ancient world. Beads on rods stand for ones, tens and hundreds.
- 1617 · Napier's bones. John Napier publishes a set of numbered rods that turn multiplication into addition.
- 1620s · The slide rule. William Oughtred and others combine logarithmic scales on sliding strips. Engineers rely on slide rules for the next 350 years.
- 1642 · The Pascaline. Blaise Pascal, still a teenager, builds a geared mechanical adder to help his father with tax calculations.
- 1673 · The stepped reckoner. Gottfried Leibniz designs a machine that can also multiply and divide.
- 1820 · The Arithmometer. Thomas de Colmar produces the first mechanical calculator sold in real numbers to offices and banks.
- 1948 · The Curta. Curt Herzstark's hand-cranked pocket calculator is small enough to hold in one hand.
- 1960s · Electronic desktop calculators. Transistors replace gears. The first models fill a desk and cost as much as a car.
- 1967 · The Cal Tech prototype. Texas Instruments builds a handheld electronic calculator that prints its results on paper tape.
- 1972 · Scientific and pocket models. The HP-35 puts trigonometry and logarithms in a shirt pocket.
- 1970s · Cheap and solar. Prices fall quickly and solar cells remove the need for batteries.
- Today · The calculator in every browser. Phones and web pages like this one do the same work instantly, for free.
About Tallyworks
Free calculators and converters that work on any device.
About
Tallyworks collects the calculators people reach for most: sums, percentages, loans, units, health numbers, timers, clocks and a few games. Every tool is free, needs no account, and works on phones, tablets and desktops.
Privacy
Calculations happen in your browser. The numbers you enter are not sent to a server and are not stored. Your chosen language is remembered on your device so the site opens the way you left it.
Terms and FAQ
Are the results exact? Results are calculated with standard formulas and shown rounded. Use them as a guide and check anything important, such as a loan or a medical figure, with a professional.
Does it cost anything? No. All tools are free to use.
Can I type on my keyboard? Yes. The basic and scientific calculators accept digits, operators, Enter, Backspace and Escape.
Which languages are supported? Use the language menu at the top of the page. Menus, tool names and page titles are translated.
Online Stopwatch
A fast, free stopwatch with lap times. Press Space to start and stop, L for a lap.
| Lap | Lap time | Total |
|---|
Countdown Timer
Set any time from one second to 99 hours. Use the presets for exams, presentations and classroom activities.
Classroom
Exams
Presentations
Interval Timer
Alternate work and rest for a set number of rounds. Good for workouts, study sprints and cooking steps. A beep marks every change.
Egg Timer
Watch the sand run down. Pick how you like your egg or set your own minutes.
Chess Clock
Two-player game clock. Tap your side after your move to pass the turn. Space also switches sides.
Digital Clock
A big, clear clock for the wall or the classroom. Choose 12 or 24 hours, a time zone and a colour.
Alarm Clock
Set one or more alarms. Keep this page open in a tab and turn your sound on, because a browser can only ring while the page is running.
| Time | Label |
|---|
Cash Clock
Turn time into money. Enter an hourly rate and start the clock to see what a meeting, a task or a call costs.
Date Countdown
Count down to a birthday, a holiday, a launch or the end of term.
Random Name Picker
Type one name per line and spin the wheel to choose a student, a winner or who goes first.
Random Number Generator
Pick numbers in any range. Turn on “no repeats” for raffle tickets and lottery-style draws.
Group Generator
Split a list of people into random teams of the size or number you choose.
Coin, Dice and 8-Ball
Three quick ways to settle it. Every result is random.
Metronome
Keep steady time. Set the tempo from 30 to 240 beats per minute, or tap the beat to match a song.
Tally Counter
Click to count people, laps, points or anything else. Space or ↑ adds, ↓ takes one away.