# Convert a date to YYYY-MM-DD format

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

Canonical: https://1loc.dev/date-time/convert-a-date-to-yyyy-mm-dd-format/
Version: 1.0.0
Runtime: JavaScript · Node.js 22 / modern browsers
Verification: Local fixtures; no external services
Updated: 2026-10-28

## Implementation

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

## Input

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

## Expected output

```json
"2026-10-28"
```

## Edge case

Input:
```json
"2026-10-28T23:30:00-03:00"
```
Output:
```json
"2026-10-29"
```

## 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 lab validates types and size before calling this function. Add equivalent validation at your own trust boundary.

## Source and license

Original: https://github.com/phuocng/1loc/blob/14b481cf60dff1620ab1bb99a43b1f68068cdd9b/contents/convert-a-date-to-yyyy-mm-dd-format.mdx
Author: Nguyen Huu Phuoc and original contributors
Contributors: ValchanOficial
Source commit: 14b481cf60dff1620ab1bb99a43b1f68068cdd9b
Copyright (c) 2020 phuoc-ng
License: MIT — https://1loc.dev/licenses/
Maintainer: Oveyon
Modifications: 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.