How to Calculate Hours Worked: A Step-by-Step Guide

Updated 5 Oct 2026 in Date & Time

Totals a shift's paid hours after breaks.

Dates and durations matter for notice periods, leave planning, project deadlines and contracts. Counting days on a calendar is slow and easy to get wrong, especially across months of different lengths.

What you need

• Clock in
• Clock out
• Unpaid break (minutes)

Step by step

1. Enter the clock in.
2. Enter the clock out.
3. Enter the unpaid break (minutes).
4. The results update as you type, or press Calculate.
5. Read the hours worked first, then the supporting figures below it.

The formula

Hours = out − in − break.

Worked example

For example, with these inputs:

• Clock in: 08:30
• Clock out: 17:45
• Unpaid break (minutes): 60

the calculator returns:

• Hours worked: 8 h 15 min
• Decimal hours: 8.25 hours

A second example

Now change the inputs to:

• Clock in: 08:30
• Clock out: 17:45
• Unpaid break (minutes): 75

the calculator returns:

• Hours worked: 8 h 00 min
• Decimal hours: 8.00 hours

Practical tips

• Convert times to minutes before subtracting, then convert back to hours and minutes.
• Notice periods in employment contracts may be counted in calendar days or working days, so read the wording carefully.
• Decide upfront whether the end date should be counted, because it changes the answer by one day.
• Months have different lengths, so 'one month' is not always 30 days.

Background

Many Singapore rules are expressed in days: notice periods, leave entitlements, stamp duty deadlines and probation periods. Whether the count includes the start or end date, and whether weekends count, changes the answer.

Age is calculated in completed years, months and days. Someone born on 29 February is usually treated as turning a year older on 28 February or 1 March in non-leap years, depending on the rule being applied.

The Gregorian calendar has months of 28 to 31 days and adds a leap day almost every four years, which makes counting days by hand surprisingly error-prone. Converting dates to day numbers and subtracting avoids the problem.

Related calculations

• Add Days to a Date Calculator: Finds the date a number of days after another date.
• Subtract Days from a Date Calculator: Finds the date a number of days before another date.
• Working Days Calculator: Counts weekdays between two dates, inclusive.
• Day of the Week Calculator: Tells you which weekday any date falls on.

Want to skip the arithmetic? The free Hours Worked Calculator does all of this instantly and updates as you type.

Run your own numbers: Hours Worked Calculator