Hours to Decimal Converter

Background.

Forty-five minutes is three-quarters of an hour, so 7 hours 45 minutes is 7.75 hours, not 7.45. It is an easy slip and an expensive one. Read as decimal hours, 7.45 means 7 hours 27 minutes, so whoever types it records 18 minutes less than was worked. At $20 an hour that is $6 gone from a single day, repeated every time the same shift is keyed in the same way.

Payroll software, invoicing tools and spreadsheets want time as one base-ten number they can multiply by a rate. Clocks and people count in sixties. The converter sits between the two: give it hours, minutes and, if you need them, seconds, and it returns decimal hours; give it a decimal figure and it hands back hours, minutes and seconds. Minutes and seconds may run past 59 and simply carry, so 90 minutes on its own comes out as 1.5 hours without any tidying first.

The second job is payroll rounding. Many US employers record time to the nearest 5 minutes, tenth of an hour or quarter of an hour, the three increments named in federal regulation 29 CFR 785.48(b). Some systems work in hundredths of an hour, the column used in the Department of Labor's hours-worked conversion chart. Choose an increment and the rounded figure appears beside the exact one, along with the signed number of minutes the rounding added or took away.

Everything here describes a length of time, not a time of day. If you have a clock-in and a clock-out, work out the span between them with the hours-between-times calculator, then bring that duration here.

What is hours to decimal converter?

Decimal hours write a duration as whole hours plus a fraction of an hour in tenths and hundredths, so a quarter of an hour is 0.25 and six minutes is 0.1. Hours-and-minutes notation divides the same hour into sixtieths. Both describe exactly the same span; they differ only in the base of the fractional part, which is why 7:45 equals 7.75 while 7.45 is a different, shorter shift. The minute and the hour are fixed by definition: NIST Special Publication 330 lists 1 min = 60 s and 1 h = 60 min = 3,600 s as exact equalities, so the conversion is identical in every country and involves no approximation. Rounding to a payroll increment is a separate, later step, governed by regulation and employer policy rather than by arithmetic.

How to use this calculator.

1. 01Choose the direction. 'Hours & minutes → decimal' turns a timesheet entry such as 8:23 into 8.3833; 'Decimal → hours & minutes' turns a figure from a payslip or invoice, such as 7.33, back into 7:19:48 so you can see the time it stands for.
2. 02Type the parts of the duration as you have them. A call-log total of 5,000 seconds can go straight into the Seconds field with the other two at zero; it carries to 1:23:20.
3. 03Leave the payroll rounding increment on 'None' for the true figure. To check a timesheet, pick the increment your employer or client actually uses; it applies in both directions.
4. 04Read 'Minutes gained or lost to rounding'. A negative number means the increment took time off; noting it shift by shift shows whether your employer's rounding evens out over a pay period.
5. 05For a weekly total, add the unrounded decimal hours from each day and round the sum once, rather than rounding every day and adding the rounded figures.

The formula.

Going to decimal is one line: H_dec = h + m ÷ 60 + s ÷ 3,600. Going back, the decimal figure is multiplied by 3,600, rounded to the nearest whole second and only then split into hours, minutes and seconds, so a carry can never show up as an impossible 0:00:60.

Rounding to an increment happens in minutes. The duration is converted to minutes, divided by the increment i, rounded to the nearest whole number, multiplied back by i and turned into hours again. The four increments are 0.6 minutes (a hundredth of an hour), 5 minutes, 6 minutes (a tenth) and 15 minutes (a quarter). Working in minutes keeps every increment a short exact number; five minutes is 0.08333… of an hour, a repeating decimal that would sit a hair off the true boundary if used directly.

An exact half rounds up, so each increment tips at half its width: 7.5 minutes past a quarter-hour mark, 3 minutes for tenths, 2.5 minutes for the 5-minute increment and 18 seconds for hundredths. Under quarter-hour rounding 7:07 therefore drops to 7:00 while 7:08 climbs to 7:15. The pattern is often called the 7-minute rule, but it is nothing more than 'nearest quarter hour' with its midpoint at 7.5 minutes. The signed difference Δ = (H_rounded − H_dec) × 60 is reported in minutes.

A worked example.

Frequently asked questions.

References& sources.

1. [1]National Institute of Standards and Technology, Special Publication 330 (9th edition) — The International System of Units (SI), Section 4, Table 8 "Non-SI units accepted for use with the SI". The source of the two exact equalities this converter is built on: "1 min = 60 s" and "1 h = 60 min = 3600 s" (and "1 d = 24 h = 86 400 s"). SP 330 is the United States edition of the BIPM SI Brochure; the BIPM site serves the same table only inside a PDF, so the NIST HTML edition is cited because it is the copy that was actually read.
2. [2]29 CFR § 785.48 "Use of time clocks", paragraph (b), headed "Rounding" practices — CFR 2024 edition, title 29, volume 3, via GovInfo. The source of the three rounding increments this page offers and of the condition printed beside every rounded result: the practice of recording start and stop times "to the nearest 5 minutes, or to the nearest one-tenth or quarter of an hour" is accepted for enforcement purposes "provided that it is used in such a manner that it will not result, over a period of time, in failure to compensate the employees properly for all the time they have actually worked". Retrieval note: the current eCFR copy redirects automated requests to an anti-bot page, so the 2024 GovInfo compilation was read instead; the 2011 compilation carries identical paragraph (b) text.
3. [3]United States Department of Labor, elaws FLSA Overtime Calculator Advisor — Hours Worked Conversion Chart. Used as the independent check on this page's conversion and on its hundredths-of-an-hour increment, which the CFR does not name. The chart instructs the reader to "convert minutes worked into hundredths or quarters of an hour" and gives a worked example: "8.38 would be the entry for a day during which an employee worked 8 hours and 23 minutes." This calculator returns 8.3833333333 exact and 8.38 at the hundredths increment — agreement. Note: the chart's numeric table itself is served as an image, so only the instruction line and that example were read.