For AI agents: the complete documentation index is available at /llms.txt, the full documentation bundle is available at /llms-full.txt, and this page is available as Markdown at /reference/bigint/sum.md.
Install massaman

    sum (for BigInts) es-toolkit

    Returns the sum of all elements in an array of BigInts.

    const total = sum(numbers);
    Info

    This function is available exclusively from es-toolkit/bigint to avoid potential conflicts with similar functions for other numeric types.

    Usage

    sum(nums)

    Use sum when you want to add up BigInts. It adds every element of the array together and returns the total.

    import { sum } from 'es-toolkit/bigint';

// Basic sum
const numbers = [1n, 2n, 3n, 4n, 5n];
const total = sum(numbers);
console.log(total); // 15n

// Negative and positive values mixed
const values = [-10n, 5n, -3n, 8n];
const result = sum(values);
console.log(result); // 0n

    An empty array returns 0n, so splitting an array and summing the parts always gives the same answer as summing the whole.

    import { sum } from 'es-toolkit/bigint';

const empty = sum([]);
console.log(empty); // 0n

const first = [1n, 2n];
const second = [3n, 4n];
console.log(sum(first) + sum(second) === sum([...first, ...second])); // true

    Unlike number, BigInt stays exact no matter how large the values get, which makes it a good fit for money in the smallest currency unit, token amounts, or database identifiers.

    import { sum } from 'es-toolkit/bigint';

// Well past Number.MAX_SAFE_INTEGER, still exact
const balances = [9007199254740993n, 9007199254740993n];
console.log(sum(balances)); // 18014398509481986n

// Total of payments stored in the smallest currency unit
const paymentsInCents = [129999n, 4550n, 87500n];
console.log(sum(paymentsInCents)); // 222049n

    Parameters

    numsreadonly bigint[]required

    The array of BigInts to sum.

    Returns

    Returns the sum of all BigInts in the array. Returns 0n for empty arrays.

    bigint
    Source: es-toolkit

    Re-exported verbatim from es-toolkit. Implementation, edge cases, and performance behavior are owned upstream. This page mirrors the documentation at the pinned version; the linked source is authoritative.