It seems like there is no maximum limit to a BigInt as per spec, which makes sense considering BigInts are supposed to be arbitrary-precision integers, whose "digits of precision are limited only by the available memory of the host system".

As for v8 specifically, according to this article on the v8 blog, the precision of BigInts are "arbitrary up to an implementation-defined limit". Unfortunately, I couldn't find any further information on how the limit is determined. Maybe someone else would be able to shed light on this based on these v8 BigInt implementation notes?

That said, based on the aforementioned articles, there doesn't seem to be a specific maximum value/size for a BigInt. Rather, it is likely determined based on the available memory on the system in some way.

Answer from zwliew on Stack Overflow
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MDN Web Docs
developer.mozilla.org › en-US › docs › Web › JavaScript › Reference › Global_Objects › BigInt
BigInt - JavaScript | MDN
A BigInt value, also sometimes just called a BigInt, is a bigint primitive, created by appending n to the end of an integer literal, or by calling the BigInt() function (without the new operator) and giving it an integer value or string value.
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W3Schools
w3schools.com › js › js_bigint.asp
JavaScript BigInt
BigInt can represent an integer of any size, limited only by available memory. JavaScript Numbers are only accurate up to 15 digits:
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npm
npmjs.com › package › big-integer
big-integer - npm
November 21, 2023 - BigInteger.js is an arbitrary-length integer library for Javascript, allowing arithmetic operations on integers of unlimited size, notwithstanding memory and time limitations.
      » npm install big-integer
    
Published   Nov 21, 2023
Version   1.6.52
Author   Peter Olson
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web.dev
web.dev › learn › javascript › data-types › bigint
BigInt | web.dev
March 31, 2024 - BigInt primitives are a relatively new addition to JavaScript, allowing mathematical operations on numbers outside the range allowed by Number.
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V8
v8.dev › features › bigint
BigInt: arbitrary-precision integers in JavaScript · V8
May 1, 2018 - BigInts are a new numeric primitive in JavaScript that can represent integers with arbitrary precision. This article walks through some use cases and explains the new functionality in Chrome 67 by comparing BigInts to Numbers in JavaScript.
Find elsewhere
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GeeksforGeeks
geeksforgeeks.org › javascript › javascript-bigint
JavaScript BigInt - GeeksforGeeks
December 4, 2025 - JavaScript BigInt is a built-in object that represents whole numbers larger than (2^{53} - 1). A BigInt value, also known as a bigint primitive, is created by appending n to an integer literal or by calling the BigInt() function with an integer ...
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Mozilla
developer.mozilla.org › en-US › docs › Web › JavaScript › Guide › Data_structures
JavaScript data types and data structures - JavaScript | MDN
July 8, 2025 - The BigInt type is a numeric primitive in JavaScript that can represent integers with arbitrary magnitude.
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LogRocket
blog.logrocket.com › home › how to use javascript’s bigint
How to use JavaScript's BigInt - LogRocket Blog
June 4, 2024 - BigInt is really important in these fields because it allows developers to safely and precisely handle huge integers, timestamps, IDs, and progress. Generally, a number in JavaScript can be used to represent an integer and even a float, such as 69 and 4.125677 respectively.
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Smashing Magazine
smashingmagazine.com › 2019 › 07 › essential-guide-javascript-newest-data-type-bigint
The Essential Guide To JavaScript’s Newest Data Type: BigInt — Smashing Magazine
July 22, 2019 - The BigInt data type aims to enable JavaScript programmers to represent integer values larger than the range supported by the Number data type. The ability to represent integers with arbitrary precision is particularly important when performing ...
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GeeksforGeeks
geeksforgeeks.org › javascript › javascript-bigint-constructor
JavaScript BigInt() Constructor - GeeksforGeeks
July 23, 2025 - The JavaScript BigInt BigInt() Constructor is used to convert any primitive data type or object to a BigInt data type. It returns a new BigInt object that represents the original value.
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DEV Community
dev.to › seanwelshbrown › using-javascript-s-bigint-data-type-4o74
Using JavaScript's BigInt Data Type - DEV Community
August 26, 2020 - Arithmetic on BigInt objects may be done using the following simple operators: +, -, *, /, **, and %. It's worth noting that built in methods using the Math object in JavaScript will not work with BigInts, and that any arithmetic being done between a BigInt and a regular Number will not work— the Number must first be coerced into a BigInt as well.
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MDN Web Docs
developer.mozilla.org › en-US › docs › Glossary › BigInt
BigInt - Glossary | MDN
In JavaScript, BigInt is a numeric data type that can represent integers in the arbitrary precision format. In other programming languages different numeric types can exist, for examples: Integers, Floats, Doubles, or Bignums.
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Mastering JS
masteringjs.io › tutorials › fundamentals › bigint-to-number
Convert a BigInt to a Number in JavaScript - Mastering JS
April 25, 2023 - BigInts are a new primitive type in JavaScript that can contain arbitrarily large integers.
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JavaScript Tutorial
javascripttutorial.net › home › javascript tutorial › javascript bigint
JavaScript BigInt
November 14, 2024 - let bigInt = 9007199254740991n;Code language: JavaScript (javascript)
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JavaScript.info
javascript.info › tutorial › the javascript language › miscellaneous
BigInt
September 21, 2020 - A bigint is created by appending n to the end of an integer literal or by calling the function BigInt that creates bigints from strings, numbers etc.
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Scaler
scaler.com › home › topics › javascript bigint library
JavaScript BigInt Library - Scaler Topics
September 29, 2023 - The JavaScript BigInt is a built-in object in javascript that is used to store the numbers that are greater than Number.MAX_SAFE_INTEGER. There are some rules to create a JavaScript BigInt value.