Duration Formatter

From raw numbers to readable time

You log elapsed: 13425 and your eyes glaze over. Is that seconds? Milliseconds? How many hours is that anyway? The Duration Formatter answers instantly — and in four different styles so the output matches whatever system you are feeding.

Pick the style your context wants

Compact — 3h 42m 5s. Dense, great for dashboards, tweets, inline status indicators. Omits zero parts so tiny durations stay tiny.

Long — 3 hours, 42 minutes, 5 seconds. Pluralizes correctly. Ideal for user-facing emails, receipts, and notifications where readability beats density.

Colon — 03:42:05 or 03:42:05.127 at millisecond precision. Matches video players, media metadata, stopwatch UIs, and most broadcast standards.

ISO 8601 — PT3H42M5S or P1DT2H. The wire format specified by RFC 3339 and used in JSON Schema, Postgres interval, and many standards-compliant APIs.

Precision control

Round to hours for high-level metrics ("session lasted ~4 hours"), minutes for meeting lengths, seconds for most logs, or milliseconds when you care about micro-benchmarks. The tool breaks your input into days, hours, minutes, seconds, and ms — and only emits the parts your precision asks for.

Common use cases

• Log enrichment — turn duration_ms columns into human text before pasting into tickets.
• Video pipelines — convert FFprobe durations into HH:MM:SS.sss cue points.
• Billing — render hoursWorked fields with pluralized long form on invoices.
• APIs — emit ISO 8601 durations for standards-compliant JSON responses.
• Monitoring — build alert messages that say 5h 12m instead of 18720.

Details worth noting

• Days overflow: 36 hours becomes 1d 12h in compact/long, but stays as 36:00:00 in colon style.
• ISO 8601 uses P prefix and T separator before time components; PT0S is the canonical zero.
• Millisecond precision in colon mode uses .sss three-digit padding.

All formatting happens locally in your browser. Nothing leaves the page.