Ruby DateTime Format Converter
Ruby's `Time#iso8601` (from the `time` library) and `DateTime#iso8601` emit ISO 8601 strings with offsets: `2026-08-13T14:30:00+00:00`. Rails adds `Time#in_time_zone` and `to_formatted_s(:iso8601)` helpers on top of these.
This converter renders your date-time in Ruby's `iso8601` form so you can predict what `Time.now.iso8601` or `t.strftime("%Y-%m-%d %H:%M:%S %z")` will print.
Ruby DateTime Format Converter Quick Reference
| Format | Pattern / Description | Example 1 | Example 2 |
|---|---|---|---|
| Ruby ISO8601 | ISO with nanoseconds | 2026-08-13T14:30:00.000000000Z | 2026-01-01T00:00:00.000000000Z |
* Examples are rendered in UTC for the fixed sample instants above.
When to Use Ruby DateTime Format
Rails API serialization
Rails serializes `Time`/`DateTime` columns as ISO 8601. Verify the exact strings your API returns for frontend parsers.
ActiveRecord timezone handling
Check how `config.time_zone` affects `created_at` output and compare UTC vs offset forms.
strftime pattern debugging
Preview common Ruby `strftime` patterns (`%Y-%m-%d`, `%F`, `%T`, `%z`) to pick the right one without trial-and-error.
Frequently Asked Questions
What does Ruby iso8601 output?
`2026-08-13T14:30:00+00:00` for a UTC time — ISO 8601 with a numeric offset. Fractions appear when microseconds are non-zero: `...T14:30:00.123+00:00`.
What is the difference between Time and DateTime in Ruby?
`Time` is a C-backed epoch-based type (fast, standard); `DateTime` is a calendar-based type with better historical range. Both have `iso8601`, but `DateTime#iso8601` uses rational seconds.
What strftime pattern gives ISO 8601?
`strftime("%Y-%m-%dT%H:%M:%S%z")` → `2026-08-13T14:30:00+0000`. Add a colon via `%:z` for `+00:00` (Ruby 1.9.3+).
How does Rails format timestamps?
Rails uses `iso8601` for JSON serialization by default. With `config.active_record.default_timezone = :utc`, DB values are read and written as UTC.
Related Time Format Converters
All Format Guides
Need to Convert Between All Formats?
Use the main Time Format Converter for instant conversion across 100+ formats — epoch, ISO 8601, RFC 3339, SQL datetime, military time and more in one click.
Open Time Format Converter