mathjs vs decimal.js vs big.js vs bignumber.js in 2026: Which Precision Library Survives Production?

Fri, 06 Nov 2026 00:00:00 +0000

Three lines of JavaScript can destroy a month of accounting:

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let total = 0;
for (let i = 0; i < 100; i++) total += 19.99;
// 1999.0000000000007

Nobody typed that number. It is what IEEE-754 double precision produces when you add 19.99 a hundred times, because 19.99 has no exact binary representation. The value is off by 7e-13 — invisible in a unit test that uses toBeCloseTo, fatal in a ledger that reconciles to the cent, in an invoice PDF, or in a payment amount sent to a gateway that rejects three decimal places. Every JavaScript team eventually hits this, and every team then asks the same question: which arbitrary-precision library do we standardize on?

Precision on Pi Stack

mathjs vs decimal.js vs big.js vs bignumber.js in 2026: Which Precision Library Survives Production?