Work out an exact age, convert between units and number systems, and see the arithmetic rather than just the answer. Everything runs in your browser.
Browse Calculators
- Number System CalculatorsAdd, subtract, multiply and divide directly in binary, octal, hex or any base to 36 – plus bit shifts and bitmask operations – all exact.14 tools
- Weight ConvertersConvert between every common weight and mass unit — metric, US and imperial, and the troy units of precious metals.80 tools
Good places to start
- Age CalculatorWork out an exact age in years, months and days, plus the totals in months, weeks, days, hours, minutes and seconds.
- Kilograms to Pounds ConverterConvert kilograms to pounds by multiplying by 2.20462262185 — the exact reciprocal of the defined 0.45359237 kg pound.
- Number to Words ConverterWrite any number out in words, including negatives and decimals, in cardinal or ordinal form.
- Binary CalculatorAdd, subtract, multiply or divide two binary numbers with exact BigInt arithmetic – the addition mode traces every column and carry for your actual operands.
- Period CalculatorEstimate your next six periods, ovulation dates and fertile windows from the first day of your last period and your usual cycle length.
All Calculators tools
- Binary CalculatorAdd, subtract, multiply or divide two binary numbers with exact BigInt arithmetic – the addition mode traces every column and carry for your actual operands.
- Binary Addition CalculatorAdd two binary numbers with a full column-by-column carry trace – see exactly where 1+1 writes 0 and carries 1, for your actual inputs.
- Binary Subtraction CalculatorSubtract one binary number from another exactly, including negative results – and see why hardware actually subtracts by adding the two’s complement.
- Binary Multiplication CalculatorMultiply two binary numbers exactly, at any length.
- Binary Division CalculatorDivide two binary numbers exactly, returning the integer quotient and the remainder separately – the form long division and hardware dividers actually produce.
- Hex CalculatorAdd, subtract, multiply or divide hexadecimal numbers exactly – with a decimal cross-check in the result so you can verify at a glance.
- Hex Addition CalculatorAdd two hexadecimal numbers exactly – columns carry at 16, so 8 + 9 writes 1 and carries 1, and the decimal cross-check confirms the result.
- Hex Subtraction CalculatorSubtract hexadecimal numbers exactly, including negative results – with borrows worth 16 rather than 10, which is where hand calculations usually slip.
- Hex Multiplication CalculatorMultiply hexadecimal numbers of any size exactly.
- Hex Division CalculatorDivide hexadecimal numbers exactly, returning quotient and remainder in hex with a decimal cross-check – useful for address arithmetic and alignment calculations.
- Octal CalculatorAdd, subtract, multiply or divide octal numbers exactly – carries and borrows happen at 8, and the decimal equivalents are shown so every step can be checked.
- Base-N CalculatorDo exact arithmetic in ANY base from 2 to 36 – pick the base, pick the operation, and get the result in that base with a decimal cross-check.
- Binary Bit Shift CalculatorShift a value left or right and see the bits move – logical shifts insert zeros, arithmetic right shift copies the sign bit, and every shift is a multiply or divide by two.
- Binary Bitmask CalculatorApply AND, OR, XOR and AND-NOT between a value and a mask, bit by bit – the four operations behind testing, setting, toggling and clearing flags.
- Age CalculatorWork out an exact age in years, months and days, plus the totals in months, weeks, days, hours, minutes and seconds.
- Period CalculatorEstimate your next six periods, ovulation dates and fertile windows from the first day of your last period and your usual cycle length.
- Angel Number CalculatorWork out the life path number for a date of birth by adding its digits down to a single digit, keeping the master numbers 11, 22 and 33.
- Love CalculatorA for-fun compatibility score worked out from the letters in two names.
- Number to Words ConverterWrite any number out in words, including negatives and decimals, in cardinal or ordinal form.
- Reading Time CalculatorEstimate how long a piece of text takes to read silently or aloud, at four reading speeds.
Frequently asked questions
Do these calculators work without an internet connection?
The arithmetic does. Every calculator here runs in your browser, so once the page has loaded, the calculation itself needs no further connection and nothing you type is sent anywhere. Reloading the page does need the connection back.
Are the binary and hexadecimal calculators exact for very large numbers?
Yes. They use arbitrary-precision integer arithmetic rather than floating point, so a 200-digit binary multiplication is exact rather than rounded. Floating point is where most online calculators quietly lose accuracy past about 15 significant digits.
Why do the binary and hex calculators show a column-by-column trace?
Because the answer alone does not tell you where a carry or a borrow happened. The trace shows each column as it is worked, which is what makes these usable for checking homework or debugging a bitwise operation rather than just producing a number.
What is the difference between a base-N calculator and a base converter?
A converter rewrites one number in another base. A calculator does arithmetic while staying in that base: it adds, subtracts, multiplies or divides two hexadecimal numbers and gives the result in hexadecimal, with a decimal cross-check beside it.
Does the age calculator handle leap years correctly?
Yes. It counts real calendar days, so a birthday on 29 February and any leap day in between are both handled. It works in whatever time zone your device is set to, which is why an age can differ by a day from a calculator running elsewhere.
Is the period calculator medical advice?
No. It projects future dates from the cycle length you enter and nothing more. Cycles vary for many reasons, the estimate is not a diagnosis, and it should not be relied on to achieve or avoid pregnancy. Anything that concerns you is a question for a clinician.
Which number bases are supported?
Any base from 2 to 36 for general conversion and arithmetic, using the digits 0-9 then A-Z. Binary, octal, decimal and hexadecimal each have dedicated tools as well, because those four carry extra behaviour worth showing, such as bit width and two's complement.
