Debug timezone offsets
Compare UTC and local output for the same ISO value.
Free browser tool
ISO Date Converter
The ISO date converter helps you inspect ISO 8601 timestamps from APIs, logs, databases, and scheduled events. Paste an ISO date and see the UTC form, local form, Unix seconds, and Unix milliseconds.
ISO timestamps are readable, but timezone offsets can still be confusing. This tool makes the converted values explicit so you can debug date handling faster.
ISO date converter
Parse ISO dates into UTC, local time, and Unix values.
What this tool does
ISO 8601 dates are common in APIs because they are readable and include timezone information when written carefully. A value like 2026-05-11T16:00:00Z clearly indicates a UTC timestamp, while offsets such as -03:00 show local relationship to UTC.
This converter parses an ISO-like date and shows UTC, local time, Unix seconds, and Unix milliseconds. It is useful when debugging schedules, logs, and API payloads that cross timezones.
Common use cases
Prepare API examples
Convert ISO dates into timestamp values expected by APIs.
Inspect scheduled events
Read exactly when an ISO timestamp will occur locally.
Example before and after
The same instant can be represented as an ISO string, Unix seconds, Unix milliseconds, or local browser time.
ISO input
2026-05-11T16:00:00ZConverted values
UTC: 2026-05-11T16:00:00.000Z
Unix seconds: 1778515200How to use
- Paste an ISO date or timestamp.
- Click Convert ISO Date.
- Review UTC, local, and Unix timestamp output.
Common errors
Missing timezone
A date without Z or an offset may be treated as local time.
Assuming local display is UTC
Browser local time uses the user's timezone and can differ from UTC.
Ambiguous date-only strings
Date-only input can be interpreted differently than full timestamps.
Why use this tool
Debug API dates and timezone offsets.
Convert ISO strings for tests.
Compare local and UTC representations.
Best practices
Include timezone information
Use Z or an explicit offset when sharing timestamps across systems.
Prefer ISO in APIs
ISO strings are self-describing and easier to inspect than raw numbers.
Convert at the edge
Store and transmit UTC, then format local time for display.
Related tools
Related guides
Unix timestamp explained
Unix timestamps count time from the Unix epoch, but seconds, milliseconds, and timezones often cause confusion.
Cron expressions explained
Cron expressions compactly describe recurring schedules, but fields, timezones, and platform differences matter.
Best practices for working with API responses
API responses are easier to debug when you validate syntax, format payloads, inspect errors, and compare changes deliberately.
FAQ
What is ISO 8601?
ISO 8601 is a common date and time format such as 2026-05-11T16:00:00Z.
What does Z mean in a date?
Z means the timestamp is expressed in UTC.
Why does local time differ?
Local output uses your browser's timezone, while UTC output uses universal time.
Is the date sent anywhere?
The tool runs in your browser and does not require login, a database, or server-side processing.