Decimal hours to hours and minutes

Model: minutes = round(hours × 60); hours = h + mm / 60

Accuracy: Decimal hours round to the nearest minute

When to use this: Use this whenever a duration is written in tenths and needed in minutes, or the other way: a Hobbs or tach reading into a logbook, a logged 1:18 into the 1.3 an invoice or a maintenance interval wants. It takes either form and returns both, so there is no mode to set.

Limitations: This is a duration, not a time of day: it is not wrapped at 24 hours, and 25 hours stays 25 hours. Minutes are rounded to the nearest whole minute, which is the resolution a logbook is kept in; a value that is not a tenth of an hour can therefore move by up to half a minute. And it does no arithmetic beyond the conversion -- adding up a column of times, or working out a duration from two clock times, is the block-time tool next door.

Worked example: 1.3 hours. Source: add-practitioner-essentials scenario: 1.3 h is 1 h 18 min. It is golden test vector v001, and every build checks the tool still gives its answer within its tolerance.

Review: Not yet independently reviewed by a geodesist.

Last verified: 2026-09-18, when a maintainer last confirmed this tool's sources at the issuer. See the sources ledger.

Status: version 1.0.0, core 0.1.0. See this tool in the verification report.

Checked against: 25 golden test vectors (download the test vectors, each with its source and tolerance). See how results are checked and every source.

Sources

• 14 CFR 1.1, General definitions (flight time), Federal Aviation Administration, Current as of the review date. "Flight time": from moving under its own power for flight until coming to rest after landing. Read free. Rules as of 2026-09-18.