How to Calculate Overtime in Decimal Hours

Step 1: Know when overtime starts

There is no single overtime threshold that applies to everyone.

Overtime may begin:

• after your contracted weekly hours
• after a set number of weekly hours
• after a daily threshold
• under another employer or sector-specific rule

For example, if your normal weekly hours are 37.50 and you work 42.75, then the hours above your normal total are:

42.75 − 37.50 = 5.25 hours

If your employer defines overtime that way, this would give 5.25 overtime hours.

The important point is to use the overtime rule that actually applies to you rather than assuming a standard threshold.

Step 2: Convert the time into decimal hours if needed

If your overtime is still shown in hours and minutes, convert it into decimal hours before doing the calculation.

For example: 5 hours 15 minutes

Convert the minutes:

15 ÷ 60 = 0.25

So: 5h 15m = 5.25 hours

If you need to convert another value, use the Hundred Hour Time Converter.

Step 3: Separate normal and overtime hours

Once you know the total worked hours and the normal-hours threshold, subtract one from the other.

The basic formula is:

Total worked hours − normal hours = overtime hours

For example:

• Total worked: 42.75 hours
• Normal hours: 37.50 hours

42.75 − 37.50 = 5.25

So the split is:

• Normal hours: 37.50
• Overtime hours: 5.25
• Total worked: 42.75

Weekly overtime example

A weekly timesheet might look like this:

If the normal weekly hours are 37.50, then:

42.75 − 37.50 = 5.25 overtime hours

So the weekly total can be split into 37.50 normal hours and 5.25 overtime hours.

How to calculate overtime pay

Once the overtime hours are known, multiply them by the overtime rate that applies.

For example:

• Normal hourly rate: £14.00
• Overtime hourly rate: £21.00

Normal pay:

37.50 × £14.00 = £525.00

Overtime pay:

5.25 × £21.00 = £110.25

Then add the two amounts:

£525.00 + £110.25 = £635.25

So the total gross pay would be £635.25.

This is a gross-pay figure before deductions such as tax, National Insurance, pension contributions or other payroll deductions.

Overtime rates are not always 1.5×

A common assumption is that overtime is always paid at time-and-a-half.

That is not necessarily the case.

An overtime rate might be:

• the normal hourly rate
• 1.25 times the normal rate
• 1.5 times the normal rate
• 2 times the normal rate
• a fixed enhanced rate
• another agreed or contractual rate

For example, if the normal hourly rate is £14.00 and overtime is paid at 1.5 times the normal rate:

£14 × 1.5 = £21.00

If 5.25 overtime hours are worked:

5.25 × £21 = £110.25 overtime pay

Use the rate that actually applies to your employment or workplace.

How unpaid breaks affect overtime

Unpaid breaks can affect the paid-hours total before overtime is calculated.

For example:

• Shift length: 9.00 hours
• Unpaid break: 30 minutes = 0.50 hours

Paid time:

9.00 − 0.50 = 8.50 hours

If overtime is based on paid working hours, the useful figure is 8.50 hours rather than the full 9-hour period between starting and finishing.

For more detail, see How Breaks Affect Payroll Hours.

What if overtime is calculated daily instead of weekly?

Some workplaces may calculate overtime using a daily threshold rather than only looking at the total for the week.

For example:

• Normal daily threshold: 8.00 hours
• Worked: 9.50 hours

Difference:

9.50 − 8.00 = 1.50 hours

If the employer’s overtime rule is based on hours above 8 per day, this could mean 1.50 overtime hours.

However, this example only applies where the workplace actually uses that rule.

Do not assume daily overtime applies simply because a shift is longer than normal.

Decimal overtime values explained

Decimal overtime figures can be confusing if you are used to normal hours and minutes.

Here are some common examples:

Remember: 5.25 hours does not mean 5 hours 25 minutes.

The decimal part must be converted back into minutes.

For example:

0.25 × 60 = 15

So 5.25 hours = 5h 15m.

Common overtime calculation mistakes

Assuming overtime always starts after 40 hours

Overtime thresholds vary.

Use the normal or contracted hours, or other threshold, that actually applies to your workplace.

Assuming overtime is always paid at 1.5×

Different employers and contracts can use different overtime rates.

Forgetting unpaid breaks

If unpaid breaks reduce paid working time, they may also reduce the hours used when assessing overtime.

Reading 5.25 as 5 hours 25 minutes

It means 5 hours 15 minutes.

Applying one pay rate to every hour

Normal hours and overtime hours may need to be calculated separately.

Rounding too early

Some time values produce repeating decimals.

Where accuracy matters, use the level of precision required by the payroll or timesheet system rather than repeatedly rounding intermediate values.

Mixing daily and weekly overtime rules

A workplace may use one approach, the other, or another method entirely.

Check which rule applies before calculating the overtime amount.

How to check your overtime record

A quick overtime check can be useful if your timesheet gives you a total-hours figure.

For example:

• Total worked: 42.75 hours
• Normal weekly hours: 37.50
• Difference: 5.25 hours

So, if overtime is defined as time worked above 37.50 hours, you would expect 5.25 overtime hours.

You can then check separately how those overtime hours should be paid.

If your overtime rate is £21 per hour:

5.25 × £21 = £110.25