🧮Time calculators

No, and this is the most expensive mistake in the subject. Seven hours and thirty minutes is 7.5 decimal hours, because thirty minutes is half of sixty, not thirty hundredths. Typing 7.30 into a payroll field that expects decimal hours underpays that shift by twelve minutes, and doing it every day for a year loses about a working week. Every calculator here prints both forms side by side so the wrong one is never the only one on screen.

Yes, and without asking you to think about it. When the end time is earlier in the day than the start, the calculation is taken across midnight rather than turned negative, and the page says so in a line under the result. An overnight shift from 22:00 to 06:00 is eight hours, and a calculator that returns minus sixteen is not being precise, it is being wrong.

Anything over forty hours in the week, at one and a half times the rate — the US federal rule under the Fair Labor Standards Act. It is deliberately the only rule built in, because overtime beyond that is set by state law, by contract or by the country you are in, and a calculator that guessed at those would be inventing numbers. The regular and overtime hours are shown separately so a different multiplier can be applied by hand.

Six-minute rounding, common on US time cards because six minutes is exactly 0.1 hours, so the decimal figure stays tidy. Quarter-hour rounding to fifteen minutes is the other common one and is legal in the US as long as it does not consistently favour the employer. The time card here offers both and defaults to none, since rounding should be a decision rather than a default.

Because it is read as four digits rather than as hours and minutes: 1830 is spoken one eight three zero, not eighteen thirty. Midnight is 0000 and is the start of the day, while 2400 is used to mark the end of one; noon is 1200. The 12-hour clock’s own trap is the opposite direction — 12:00 AM is midnight and 12:00 PM is noon, which is the reverse of what most people guess.