Convert a date to YYYY-MM-DD format

Format an ISO date-time as its UTC calendar date.

JavaScript Version 1.0.0 · MIT · .md

function formatYmd(dateTime) { return new Date(dateTime).toISOString().slice(0, 10); }

Try in the local lab Download function

Input & expected output

Input

"2026-10-28T14:00:00Z"

Expected output

"2026-10-28"

The edge case

Input

"2026-10-28T23:30:00-03:00"

Expected output

"2026-10-29"

Know the limits

This is the UTC date. A local evening can already be tomorrow in UTC, as the edge case shows.
The lab accepts ISO 8601 date-times with Z or an explicit offset; ambiguous strings are rejected.

The function above is the implementation used by the lab. The lab validates JSON types and caps size before execution; include equivalent validation when accepting untrusted input in your application.

Source & maintenance

Accepts a validated ISO 8601 date-time string; documents the UTC calendar date with an offset edge case. Original MDX retained as inert source evidence.

Maintained by Oveyon. Source commit: 14b481cf60df. Read the license.

Local fixture scope · Node.js 22.23.2 · reviewed October 28, 2026. No external service is required.

Keep exploring

Compare two dates — Compare validated ISO calendar dates in UTC and return -1, 0 or 1.
Add AM PM suffix to an hour — Turn an hour from 0 to 23 into a 12-hour label with am or pm.
Calculate the number of days between two dates — Count whole calendar days between two YYYY-MM-DD dates.