Why it matters
Logs, databases, APIs and JWTs store time as Unix timestamps, the number of seconds since 1 January 1970 UTC. They're perfect for computers and unreadable for people, and mixing up seconds and milliseconds puts a date in 1970 or the year 50,000.
Time zones add another trap: a server in UTC, a client in London and summer time changing twice a year. This converter shows every view at once, using your browser's own time zone data.
How it works
- InputSeconds, milliseconds, ISO dates or words
- In your browserRead as an instant, shown in each time zone
- OutputISO, RFC, local, relative and CSV
Where it fits in a designer's workflow
- Plan
- Design
- Build
- Test
- Launch
By the numbers
Show the numbers as a table
| Milestone | Timestamp | UTC |
|---|---|---|
| The epoch | 0 | 1970-01-01 00:00:00 UTC |
| 1 billion seconds | 1,000,000,000 | 2001-09-09 01:46:40 UTC |
| 1.5 billion | 1,500,000,000 | 2017-07-14 02:40:00 UTC |
| 1.7 billion | 1,700,000,000 | 2023-11-14 22:13:20 UTC |
| 1.8 billion | 1,800,000,000 | 2027-01-15 08:00:00 UTC |
| 2 billion | 2,000,000,000 | 2033-05-18 03:33:20 UTC |
| Signed 32-bit limit (2^31 − 1) | 2,147,483,647 | 2038-01-19 03:14:07 UTC |
How to use it
- Type a timestamp or a date, or press Now.
- List any extra time zones you need.
- Read the formats in the table.
- For many values, paste them below and download the CSV.
FAQ
Seconds or milliseconds?
10 digits is seconds (used by Unix, PHP and most APIs); 13 digits is milliseconds (used by JavaScript). The converter detects which.
Does it handle British Summer Time?
Yes. Time zones use your browser's built-in database, so BST and GMT are applied on the right dates.
What's the year 2038 problem?
Systems that store seconds in a signed 32-bit number overflow on 19 January 2038. Modern systems use 64 bits.
Why does my date show a day out?
A date without a time or zone, such as 2026-10-30, is read as midnight UTC, which can be the previous evening in the Americas.
