Big Integer Arbitrary-Precision Calculator
Evaluate arbitrary-precision integer arithmetic with native BigInt: +, -, *, /, %, **, GCD, LCM, factorial, Fibonacci, modular exponentiation (a^b mod m), Miller-Rabin primality test, base conversion (binary/octal/decimal/hex/base-N up to 36), exact rational mode (fractions kept exact, not floated), and a full shunting-yard expression parser with precedence and parentheses. Result digit count + grouped display + scientific approximation. 100% client-side, no network, no libraries.
About Big Integer Arbitrary-Precision Calculator
Evaluate arbitrary-precision integer arithmetic with native BigInt: +, -, *, /, %, **, GCD, LCM, factorial, Fibonacci, modular exponentiation (a^b mod m), Miller-Rabin primality test, base conversion (binary/octal/decimal/hex/base-N up to 36), exact rational mode (fractions kept exact, not floated), and a full shunting-yard expression parser with precedence and parentheses. Result digit count + grouped display + scientific approximation. 100% client-side, no network, no libraries. Everything runs locally in your browser — your data never leaves your device.
How to use
- Enter your input in the tool above.
- Adjust any options to your preference.
- Use the Copy or Download buttons to save the result.
- Everything happens locally — your data never leaves your browser.
FAQ
What can the big integer calculator do?
It evaluates arithmetic on integers of unlimited size using JavaScript's native BigInt. Supported operations: addition (+), subtraction (-), multiplication (*), integer division (/) with remainder (%), power (**), GCD, LCM, factorial (n!), Fibonacci, and modular exponentiation (a^b mod m). You can type a single full expression with parentheses (e.g. `(2^1000) + (3 * 5!) - 7`) and the shunting-yard parser evaluates it with correct precedence. Each result shows the exact value, digit count, thousands-grouped display, a scientific approximation, and the value converted to binary / octal / hex.
How does the exact rational (fraction) mode work?
When a division does not divide evenly, the result is kept as an exact fraction (numerator/denominator) reduced to lowest terms via BigInt GCD — never as a floating-point approximation. So `1 / 3` is exactly `1/3`, not `0.3333...`. You can chain further operations on the fraction (`(1/3) + (1/6) = 1/2`) and the result stays exact. The fraction is also rendered as a decimal expansion with a configurable digit limit.
How is primality tested for very large numbers?
The tool uses a deterministic Miller-Rabin test. For n < 3,317,044,064,679,887,385,961,981 the test is provably correct using the first 13 prime witnesses. For larger n it falls back to a high-confidence probabilistic Miller-Rabin with 40 rounds, which gives a false-positive probability below 2^-80 — far stronger than cryptographic requirements. Small composites are caught first by trial division by the first 200 primes.
Are extremely large computations like 100000! going to crash my browser?
BigInt operations are native and fast, but truly enormous results (e.g. factorial of 100000 produces a ~456574-digit number) take time and memory. The tool runs in the main thread but yields to the event loop between independent operations so the UI stays responsive. Very long computations can be canceled via the cancel button. There is a configurable safety bound on factorial input to prevent accidental hangs.
What extra features does this tool have compared to other big integer calculators?
(1) Full shunting-yard expression parser with precedence and parentheses (most only do two operands and one op). (2) Exact rational mode (fractions kept exact, not floated). (3) Modular exponentiation (a^b mod m) with large inputs. (4) Miller-Rabin primality test (deterministic under ~3.3*10^24, probabilistic above). (5) Factorial and Fibonacci for any n. (6) GCD and LCM. (7) Base conversion (bin/oct/dec/hex/base-N up to 36) for both input and output. (8) Result digit count + thousands-grouped display + scientific approximation. (9) History (localStorage, last 20, clickable to reload). (10) Shareable URL with full expression round-trip. (11) Niche presets (e.g. 2^256, 10!, 100th Fibonacci, RSA-100). (12) Copy result / fraction / decimal expansion. 100% client-side and offline — your numbers never leave the device.
Related tools
.bashrc / .zshrc Alias & Config Manager
Build shell aliases, functions, exports, and PATH edits in a visual editor, then export a clean, commented .aliases file sourced from both .bashrc and .zshrc — with shadowing detection against shell builtins and common CLI tools, function suggestions when args are needed, starter packs (git, docker, kubectl, navigation, safety, ls, dev, devops, data science), import of existing rc files, dedupe, history (localStorage), and shareable URL. 100% client-side.
Add / Subtract Date Calculator
Add or subtract years, months, weeks, days, hours, minutes and seconds from a starting date/time. Calendar-day or business-day mode with custom weekend + holiday list. Month-end policy toggle (clamp to last day vs overflow). Repeat/series mode (e.g. every 2 weeks x 10) with CSV export. Shareable URL. 100% client-side.
Age Calculator
Calculate exact age from a birth date in calendar years/months/days (no negative-day bugs) plus totals in months/weeks/days/hours/minutes/seconds. Next-birthday countdown with weekday. Feb-29 birthday policy toggle. Milestones (1,000 days, 10,000 days, 1 billion seconds). Zodiac sign + Chinese zodiac. Age gap comparison. Shareable URL. 100% client-side.