JavaScript Date UTC() Method

What You’ll Learn

Date.UTC() is a static method that builds epoch milliseconds from UTC calendar parts—year, month, day, hour, and so on. Wrap the result in new Date(...) for a Date object, then verify with toISOString().

Introduction

When you write new Date(2026, 2, 15), JavaScript treats those numbers as local calendar fields. When you need a specific instant in Coordinated Universal Time regardless of the user’s timezone, Date.UTC() interprets the same-style arguments as UTC instead.

The method returns a number—milliseconds since the Unix epoch—not a Date object. Pass that number to new Date(...) or setTime(). Pair with toUTCString() and toISOString() to inspect the result.

Understanding the Date.UTC() Method

Date.UTC(year, month[, day[, hour[, minute[, second[, millisecond]]]]]) computes one UTC instant and returns its epoch milliseconds:

• Static — call on the Date constructor, not on an instance.
• UTC interpretation — all supplied parts are UTC, not local.
• Zero-indexed month — 0 = January, 11 = December.
• Defaults — omitted day becomes 1; omitted time fields become 0.
• Overflow — out-of-range values roll over (month 13 becomes next year).

📝 Syntax

Date.UTC(year, month[, day[, hour[, minute[, second[, millisecond]]]]])

Parameters

• year — four-digit year (for example, 2026).
• month — 0–11 (0 = January).
• day (optional) — 1–31; defaults to 1.
• hour (optional) — 0–23; defaults to 0.
• minute (optional) — 0–59; defaults to 0.
• second (optional) — 0–59; defaults to 0.
• millisecond (optional) — 0–999; defaults to 0.

Return value

• Epoch milliseconds for the UTC date-time described by the arguments.
• Not a Date object—wrap with new Date(Date.UTC(...)) when you need one.

Examples Gallery

Open DevTools Console (F12) or use Try-it links. UTC examples verify cleanly with toISOString().

const ms = Date.UTC(2026, 2, 15, 12, 30, 45);
const date = new Date(ms);

console.log(ms);
console.log(date.toISOString());
// "2026-03-15T12:30:45.000Z"

1773575445000
2026-03-15T12:30:45.000Z

const utcDate = new Date(Date.UTC(2026, 2, 15, 12, 0, 0));
const localDate = new Date(2026, 2, 15, 12, 0, 0);

console.log(utcDate.toISOString());
console.log(localDate.toISOString());

2026-03-15T12:00:00.000Z
2026-03-15T06:30:00.000Z  (local line varies by timezone)

const march = new Date(Date.UTC(2026, 2, 1));
const april = new Date(Date.UTC(2026, 3, 1));

console.log(march.toISOString().slice(0, 10)); // "2026-03-01"
console.log(april.toISOString().slice(0, 10));  // "2026-04-01"

2026-03-01
2026-04-01

const ms = Date.UTC(2026, 0); // Jan only
const date = new Date(ms);

console.log(date.toISOString());
// "2026-01-01T00:00:00.000Z"

2026-01-01T00:00:00.000Z

const start = Date.UTC(2026, 0, 1);
const end = Date.UTC(2026, 6, 1);

const diffMs = end - start;
const diffDays = diffMs / (1000 * 60 * 60 * 24);

console.log(diffMs);
console.log(diffDays); // 181 days

15638400000
181

🚀 Common Use Cases

• Tutorial examples — predictable UTC instants in docs and tests.
• Deadline comparisons — compare now against a fixed UTC milestone.
• Chart axes — generate UTC tick marks from numeric parts.
• Server schedules — encode “every day at 09:00 UTC” consistently.
• Unit tests — assert ISO output after UTC construction.
• setTime input — pass Date.UTC(...) to move an existing Date.

📝 Notes

• Static method—call Date.UTC(), not date.UTC().
• Returns a number, not a Date object.
• Months are zero-indexed; March is 2.
• Arguments are UTC; local constructor uses local timezone.
• Overflow rolls (for example, month 12 becomes January next year).
• For “now”, use Date.now() instead of Date.UTC().

💡 Best Practices