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Unix Time Converter

Convert Unix timestamps to readable date and back

About Unix Time Converter

Unix Time Converter on UtilityKit converts between Unix epoch timestamps and human-readable dates in both directions: paste a raw integer and see the UTC date plus your local timezone equivalent, or pick a calendar date and get the epoch seconds ready for code, APIs, or database queries. Unix time — seconds elapsed since 00:00:00 UTC on 1 January 1970 — is the universal format across backend systems, logs, cloud APIs, and JWT claims. The tool auto-detects scale: 10-digit inputs are seconds; 13-digit inputs are JavaScript milliseconds. Output shows both the ISO 8601 UTC string and your locale-formatted local time. A Now button stamps the current second instantly. The reverse direction accepts a datetime picker and outputs the floor-second integer ready to paste into a curl command, SQL WHERE clause, or JWT exp field.

Why use Unix Time Converter

Auto-Detects Seconds vs Milliseconds

10-digit inputs are treated as seconds (standard Unix); 13-digit inputs are treated as JavaScript milliseconds — no manual mode switching needed when working across different systems.

Simultaneous UTC and Local Time Output

The result always shows both the ISO 8601 UTC string and your browser's locale-formatted local time, so you never have to mentally subtract your UTC offset.

Instant 'Now' Snapshot

The Now button stamps the current second as a Unix timestamp and converts it immediately — useful for generating test values, documenting when a config was set, or checking the current epoch without arithmetic.

Bidirectional — Date to Timestamp Too

Pick any calendar date and time and get the exact Unix timestamp back in seconds, ready to paste into a curl parameter, SQL WHERE clause, or JWT exp field.

Debug Logs and JWT Claims Quickly

Server logs and JWT payloads surface epoch integers that are unreadable at a glance. Paste them here to confirm whether a token is expired or a log event occurred in the right time window.

Browser-Only — Works Offline and Without Sign-Up

Date arithmetic runs entirely in the browser using the native JavaScript Date API. No server, no account, and no Internet connection required once the page has loaded.

How to use Unix Time Converter

  1. To convert a timestamp to a date: paste or type the Unix timestamp (seconds or milliseconds) into the 'Unix timestamp' field.
  2. Click 'Timestamp → Date' — the tool outputs the ISO 8601 UTC representation and your browser's local time equivalent.
  3. To convert a date to a timestamp: click the calendar icon in the 'Human date/time' field and select the date and time you need.
  4. Click 'Date → Timestamp' — the output shows the corresponding Unix timestamp in seconds.
  5. Click 'Now' to instantly populate the current second as a Unix timestamp and display it as a human-readable date without typing anything.
  6. Copy the result from the output field — it includes both the UTC ISO string and the local time so you have both representations at once.

When to use Unix Time Converter

  • When a server log or database record shows a large integer and you need to know what date and time it represents in human terms.
  • When a JWT token's exp or iat claim is an epoch integer and you need to verify whether the token is still valid or has already expired.
  • When writing a curl command or SQL query with a date filter and you need the exact Unix timestamp for a specific calendar date and time.
  • When a cloud API (AWS, GCP, Stripe, GitHub) returns an event timestamp as epoch seconds and you need to correlate it with a local event timeline.
  • When debugging a time-based bug where two systems disagree on event ordering and you need to verify whether each system's timestamp resolves to the same instant.
  • When generating test data that requires realistic past or future Unix timestamps and you need to pick a date and get the integer value quickly.

Examples

Decode a JWT exp claim

Input: 1746057600

Output: 2025-05-01T00:00:00.000Z (local: 1 May 2025, 00:00:00 in your timezone)

Convert a JavaScript millisecond timestamp

Input: 1715000000000

Output: 2024-05-06T20:13:20.000Z (13-digit inputs auto-detected as milliseconds)

Get epoch seconds for a specific deployment date

Input: 2025-01-15 09:00 (selected via date picker)

Output: 1736931600 — paste directly into a cron trigger, SQL WHERE clause, or API parameter

Tips

  • When working with JWT tokens, paste the exp claim integer directly — if the resulting date is in the past, the token has expired. The ISO 8601 output makes it immediately obvious.
  • The Now button is useful for generating a stable reference timestamp at the moment a deployment starts or a config change is applied — capture it once without having to open a terminal.
  • If a timestamp you got from a JavaScript application looks 1000x too large (e.g. 13 digits), it is milliseconds — the converter handles this automatically, but trim trailing zeros if you are converting to a system expecting seconds.
  • To find the Unix timestamp exactly 30 days from now: click Now, note the output, then manually add 2,592,000 (30 × 86400) to the second value for a simple forward projection.
  • ISO 8601 output (e.g. 2024-05-06T20:13:20.000Z) can be pasted directly into most database timestamp fields, REST API bodies, and documentation — it is universally parseable.

Frequently Asked Questions

Does it expect seconds or milliseconds?▾
The tool accepts both. A 10-digit input is treated as seconds (standard Unix epoch, e.g. 1715000000). A 13-digit input is treated as milliseconds (JavaScript Date.now() format, e.g. 1715000000000). The conversion handles the correct scale automatically.
What timezone does the output use?▾
The output always includes the ISO 8601 UTC representation (e.g. 2024-05-06T20:13:20.000Z) alongside your browser's locale-formatted local time. UTC is timezone-independent; the local time reflects the timezone configured in your operating system.
What is the Unix epoch and why does it start on 1 January 1970?▾
The Unix epoch is the point in time — 00:00:00 UTC on 1 January 1970 — from which Unix systems count seconds. It was chosen by the original Unix designers as a practical starting point. All subsequent timestamps are positive integers counting seconds from that moment.
What is the maximum date this tool can represent?▾
JavaScript's Date object supports timestamps up to ±8,640,000,000,000,000 milliseconds from the epoch, which covers dates from about 271,821 BC to 275,760 AD — far beyond any practical scheduling need.
What does 'Date → Timestamp' output?▾
It outputs the floor-second Unix timestamp for the date and time you selected in the datetime picker, using your browser's local timezone as the reference. The result is an integer — the number of seconds since the Unix epoch at that moment.
Why is there a 1–2 second difference between what I expect and the output?▾
This usually happens when the input timestamp is in milliseconds but is being read as seconds, or vice versa. Check the digit count: 10 digits = seconds, 13 digits = milliseconds. Also confirm that your OS clock is accurate.
Can I convert a negative Unix timestamp?▾
Yes. Negative values represent dates before the Unix epoch (before 1 January 1970). Enter a negative integer and the tool converts it to the correct historical date.
Is Unix Time Converter free to use?▾
Yes. Unix Time Converter on UtilityKit is completely free with no account, no sign-up, and no usage limits.

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Glossary

Unix epoch
The reference point for Unix timestamps: 00:00:00 UTC on Thursday, 1 January 1970. All Unix timestamps are the number of seconds (or milliseconds) elapsed since this moment.
Unix timestamp
An integer representing a point in time as the number of seconds elapsed since the Unix epoch. A 10-digit integer represents a date in the range 2001–2286.
ISO 8601
An international standard for representing dates and times (e.g. 2024-05-06T20:13:20.000Z). The trailing Z indicates UTC. Universally parseable by databases, APIs, and programming languages.
Millisecond timestamp
A 13-digit Unix-style timestamp counting milliseconds since the epoch. Used by JavaScript's Date.now(), Java System.currentTimeMillis(), and many cloud APIs. Divide by 1000 to get seconds.
UTC (Coordinated Universal Time)
The primary time standard against which the world's clocks are regulated. Unix timestamps always count from the UTC epoch regardless of the local timezone of the system producing them.
JWT exp claim
A field in a JSON Web Token payload that specifies the expiration time as a Unix timestamp in seconds. If exp is in the past relative to the current time, the token is expired and must be rejected.