How Unix Timestamp Converter Works

This tool performs two-way conversion between epoch values and calendar dates. In “Unix → Human” mode, it interprets the number as seconds or milliseconds since the Unix epoch and formats it into readable timestamps. In “Human → Unix” mode, it parses a date-time string in a selected time zone and returns the corresponding Unix timestamp in seconds and milliseconds.

Step-by-Step

• 1) Choose a conversion mode: pick whether you want to decode an epoch number into a date, or encode a date into an epoch number.
• 2) Set the unit: choose seconds (common in APIs and logs) or milliseconds (common in JavaScript and event tracking).
• 3) Select a time zone: decide how you want the readable date displayed (or how an input date should be interpreted).
• 4) Paste your value: enter an integer timestamp like 1700000000 or a date-time like 2026-02-22 14:30:00.
• 5) Convert: the result panel shows the formatted date, ISO 8601 output, and helpful details you can copy or download.

Key Features

Bidirectional conversion

Switch between converting Unix time to a readable date and converting readable dates back into Unix timestamps. This is ideal when you are debugging an API response, validating a webhook payload, or writing migration scripts that require consistent time handling.

Seconds and milliseconds support

Many systems store epoch values in seconds, but browsers and JavaScript runtimes often use milliseconds. The unit selector ensures you can accurately decode values without manually adding or removing three digits.

Time zone awareness

When viewing a timestamp, the same moment can appear as different wall-clock times depending on time zone. This tool lets you display a moment in common time zones such as UTC and Europe/Warsaw, and it also helps you interpret an input date in a chosen zone before converting it to epoch time.

Copy and download output

Once converted, you can copy the result in one click or download the output as a TXT file for sharing in tickets, PR comments, incident reports, or documentation. Keeping the output in plain text makes it easy to paste into any system.

Practical formats

Output includes ISO 8601 (widely used in APIs), a readable “YYYY-MM-DD HH:MM:SS” format, and a UTC reference. These formats reduce ambiguity when comparing values across services and logs.

Use Cases

• API debugging: decode epoch fields from REST or GraphQL responses to verify expiration, issued-at, or event times.
• Log analysis: convert timestamps from server logs or observability tools to quickly understand incident timelines.
• Frontend/backend alignment: ensure JavaScript millisecond timestamps match backend second-based fields without off-by-1000 errors.
• Database migration checks: validate that stored epoch values map to the expected calendar dates before and after migrations.
• Scheduling and cron work: confirm the exact moment a job is expected to run, including differences between UTC and local zones.
• Security token validation: inspect JWT “iat” and “exp” fields, which are commonly expressed in seconds since epoch.
• Analytics and tracking: interpret event timestamps from tracking pixels, mobile SDKs, or ETL pipelines that use milliseconds.

Whether you are building software, auditing a system, or simply trying to understand when an event happened, consistent timestamp conversion saves time and prevents subtle bugs caused by unit mismatches or time zone assumptions.

Optimization Tips

Always confirm the unit

If your timestamp looks “too large” (for example, 13 digits instead of 10), it is likely milliseconds. Use the unit selector to match the source system. A common mistake is treating milliseconds as seconds, which produces a date far in the future.

Use UTC as a baseline

When troubleshooting distributed systems, compare values in UTC to eliminate local time differences and daylight-saving confusion. After you verify the UTC moment, switch to a local zone for user-facing interpretation.

Prefer ISO 8601 in integrations

When you need to communicate a moment in time across teams or services, ISO 8601 is precise and widely understood. Use it in documentation and payload examples to avoid ambiguity and to keep time zone offsets explicit.

FAQ

Common Pitfalls and How to Avoid Them

Mixing local time with UTC

A frequent source of confusion is assuming a timestamp is “local time”. Unix timestamps are anchored to UTC, so they always represent an absolute instant. When you display that instant for a user in a local zone, the clock time shifts by the zone offset. For auditing and backend logic, keep the canonical representation in UTC and only localize at the edges (UI and reporting).

Off-by-one errors around midnight

When you convert a date string without a time component, some systems default to midnight. If you interpret an input like 2026-02-22 in different zones, the resulting UTC instant can land on a different calendar day. To avoid this, include a full time (HH:MM:SS) when precision matters and confirm the zone used for interpretation.

Milliseconds precision expectations

Even if you store timestamps in milliseconds, downstream systems might round to seconds. The unit selector in this tool helps you normalize values for comparison. If you see an unexpected three-digit remainder, verify whether the source uses true milliseconds or a different precision such as microseconds.

Negative epoch values

Dates before 1970 are represented as negative Unix timestamps. Not every system handles negative values consistently, especially in older databases or libraries. If you work with historical datasets, test conversions in UTC first and confirm that all services in your pipeline support negative epoch values.

Format Reference

The converter is designed to accept common date-time formats used in engineering workflows. If your input includes an explicit offset (for example, 2026-02-22T14:30:00+01:00), that offset defines the moment; if your input is “naive” (no offset), the selected time zone is used to interpret it.

Accepted examples

• ISO 8601: 2026-02-22T14:30:00 or 2026-02-22T14:30:00Z
• Space-separated: 2026-02-22 14:30:00
• Date only: 2026-02-22 (interpreted as 00:00:00 in the chosen zone)
• Epoch seconds: 1700000000
• Epoch milliseconds: 1700000000000

For integrations, prefer ISO 8601 with an explicit offset or Z suffix. It travels well across languages and makes time zone intent unambiguous.