JavaScript Date getUTCDay() Method

What You’ll Learn

getUTCDay() returns the day of the week (0–6) from a Date object in UTC. This guide covers syntax, the Sunday–Saturday index table, five examples, comparisons with local getters, and safe UTC scheduling patterns.

Introduction

Global apps often bucket data by UTC weekdays—for example, “reporting week starts on UTC Monday.” The JavaScript Date object stores one instant; getUTCDay() reads the weekday index according to UTC, not the user’s local timezone.

If you need the weekday in the user’s locale, use getDay() or Intl.DateTimeFormat. Use getUTCDay() when your logic follows UTC calendar boundaries.

Understanding the getUTCDay() Method

Date.prototype.getUTCDay() is a zero-argument instance method. It never mutates the original Date—it only reads the UTC weekday component.

The return value is always an integer: 0 = Sunday through 6 = Saturday. To show a name, map the index to a string array or use locale formatters with timeZone: "UTC".

📝 Syntax

dateObj.getUTCDay()

Parameters

• None.

Return value

• Integer 0–6 for a valid date in UTC (0 = Sunday).
• NaN if dateObj is an invalid Date.

Weekday index table

• 0 — Sunday
• 1 — Monday
• 2 — Tuesday
• 3 — Wednesday
• 4 — Thursday
• 5 — Friday
• 6 — Saturday

Examples Gallery

Open DevTools Console (F12) or use Try-it links. Fixed UTC dates use Date.UTC or ISO strings ending in Z for predictable results.

const feb26Utc = new Date(Date.UTC(2024, 1, 26));
const dayOfWeek = feb26Utc.getUTCDay();

console.log(dayOfWeek); // 1 (Monday)

1

const WEEKDAYS = [
  "Sunday", "Monday", "Tuesday", "Wednesday",
  "Thursday", "Friday", "Saturday"
];

function getUtcDayName(date) {
  return WEEKDAYS[date.getUTCDay()];
}

const sample = new Date(Date.UTC(2024, 1, 26));
console.log("UTC weekday:", getUtcDayName(sample));
// UTC weekday: Monday

UTC weekday: Monday

function safeGetUTCDay(date) {
  if (!(date instanceof Date) || Number.isNaN(date.getTime())) {
    return null;
  }
  return date.getUTCDay();
}

console.log(safeGetUTCDay(new Date()));              // e.g. 5
console.log(safeGetUTCDay(new Date("not-a-date"))); // null

5
null

// Saturday, Feb 24, 2024 UTC
const saturdayUtc = new Date(Date.UTC(2024, 1, 24));
const day = saturdayUtc.getUTCDay();

if (day === 0 || day === 6) {
  console.log("UTC weekend");
} else {
  console.log("UTC weekday");
}

UTC weekend

// Jan 31, 2026 at 23:30 UTC (Saturday in UTC)
const date = new Date("2026-01-31T23:30:00.000Z");

console.log("UTC weekday:", date.getUTCDay());   // 6
console.log("Local weekday:", date.getDay());    // depends on timezone

UTC weekday: 6
Local weekday: 0

🚀 Common Use Cases

• UTC cron jobs — run tasks only on specific UTC weekdays.
• Global analytics — bucket events by UTC weekday index.
• Maintenance windows — skip UTC Saturday/Sunday deploys.
• API logs — label timestamps with UTC weekday for support.
• Recurring UTC events — “every UTC Tuesday” logic.
• Debug panels — show local and UTC weekday side by side.

📝 Notes

• getUTCDay() is UTC; use getDay() for local UI rules.
• Do not confuse with getUTCDate() (day of month 1–31).
• Sunday is 0, not 7.
• Invalid dates propagate NaN—validate with Number.isNaN(date.getTime()).
• Locale first-day-of-week settings do not change the numeric index—only how you label it.
• For localized weekday names in UTC, use Intl.DateTimeFormat with timeZone: "UTC".

💡 Best Practices