Maternity Pay Calculator: How To Calculate Maternity Pay Explained

Calculating maternity pay is easier when you break it into a few steps. You can do it with an online maternity pay calculator if you want to, or you can use simple formulas to work out how much maternity pay an employee should receive. To get the right amount, you need to work out which earnings count, calculate the employee’s average weekly earnings, and then use the correct Statutory Maternity Pay rate.

For 2026/27, eligible employees receive 90% of their average weekly earnings for the first six weeks. For the next 33 weeks, they receive £194.32 per week or 90% of their average weekly earnings, whichever is lower.

This guide explains how to calculate maternity pay step by step, with simple examples for employees on different pay levels. If you need information about eligibility, notice periods, maternity leave or employee rights first, see Factorial’s full guide to Statutory Maternity Pay and Leave. You can also use the official HMRC maternity pay calculator to check your figures.

Overview of maternity pay calculation

For an employee who qualifies for Statutory Maternity Pay (SMP), the basic calculation for maternity pay is:

The main challenge is usually working out the employee’s average weekly earnings correctly. Their normal salary is not always enough. Things like overtime, commission and bonuses paid during the relevant period can also affect the calculation.

What information do you need to calculate maternity pay?

Before starting, gather the information you will need to calculate maternity pay.

This normally includes:

• the baby’s expected due date
• the employee’s qualifying week
• their normal paydays
• their gross earnings during the relevant period
• any bonuses, commission or overtime paid during that period
• how often they are paid
• their planned SMP start date

You should also confirm that the employee qualifies for SMP before calculating the amount. Factorial’s Statutory Maternity Pay guide covers the eligibility rules in more detail. Once you have all the information you need, you can work through the calculation step by step.

Step 1: Find the relevant period

Statutory Maternity Pay is based on the employee’s earnings during a specific period called the relevant period. This is normally an eight-week period before the employee’s qualifying week.

More precisely, HMRC normally uses the period between:

• the last normal payday on or before the end of the qualifying week, and
• the day after the last normal payday at least eight weeks earlier.

GOV.UK explains the rules in detail: For an employee paid monthly, the relevant period will often cover two normal monthly paydays. The dates are important because only earnings paid during the correct relevant period are normally used to calculate average weekly earnings.

Why the relevant period matters for maternity calculation

Imagine an employee receives a large bonus. If it is paid inside the relevant period, it may increase their average weekly earnings and therefore their maternity pay.

If the same bonus is paid outside the relevant period, it may not form part of the calculation. This is why you should find the correct dates before adding up earnings.

Step 2: Add up the employee's relevant earnings

Next, work out how much the employee earned during the relevant period.

You will normally include gross earnings that are subject to Class 1 National Insurance, or would be if the amount was high enough.

This can include:

• basic salary or wages
• overtime
• commission
• bonuses
• shift payments
• other qualifying earnings

Do not simply take the employee’s annual salary and divide it by 52 if they received other qualifying payments during the relevant period.

For example, imagine an employee earns a basic £3,000 per month but also receives a £1,000 bonus during the relevant period.

That bonus may need to be included when calculating their maternity pay.

Factorial’s guide to employee bonus schemes explains the different types of bonuses employers may use.

Step 3: Calculate average weekly earnings

Once you know the relevant earnings, you need to turn them into average weekly earnings, or AWE.

How you do this depends on how often the employee is normally paid.

Weekly-paid employees

For someone who is paid weekly, the calculation is usually straightforward:

Total relevant earnings / number of weeks = average weekly earnings

For example:

£4,000 / 8 = £500 AWE

Their average weekly earnings are therefore £500.

Monthly-paid employees

For an employee who is normally paid monthly, HMRC generally uses this calculation:

1. Add together the earnings paid during the relevant period.
2. Divide the total by the number of months covered.
3. Multiply that figure by 12.
4. Divide by 52.

For example, imagine the employee received:

• Month 1: £3,000
• Month 2: £3,000

Total relevant earnings:

£3,000 + £3,000 = £6,000

Average monthly earnings:

£6,000 / 2 = £3,000

Turn that into annual earnings:

£3,000 x 12 = £36,000

Then divide by 52:

£36,000 / 52 = £692.31

The employee’s AWE is therefore approximately £692.31.

Monthly-paid employee with a bonus

Now imagine the same employee receives a £1,000 bonus during the relevant period.

Their relevant earnings become:

£3,000 + £4,000 = £7,000

Average monthly earnings:

£7,000 / 2 = £3,500

Annualised:

£3,500 x 12 = £42,000

Average weekly earnings:

£42,000 / 52 = £807.69

Their AWE has increased from £692.31 to £807.69 because the qualifying bonus was paid during the relevant period. This is one reason maternity pay can be different from what you might expect from the employee’s basic salary alone.

For more general examples of gross pay, deductions and payslip calculations, see Factorial’s guide to calculating payslips.

Step 4: Calculate the first six weeks of maternity pay

Once you have the employee’s AWE, calculating the first six weeks is simple.

The employee receives:

90% of AWE

There is no £194.32 cap during these first six weeks.

Example

If the employee’s AWE is £500:

£500 x 90% = £450

They receive:

£450 per week for six weeks

Their total SMP for the first six weeks would therefore be:

£450 x 6 = £2,700

Step 5: Calculate weeks 7 to 39

The calculation changes after the first six weeks.

For weeks 7 to 39, pay the lower of:

• £194.32 per week, or
• 90% of the employee’s AWE

This “whichever is lower” rule is important.

Example with higher earnings

An employee has AWE of £500.

90% is:

£500 x 90% = £450

Compare:

• £450
• £194.32

£194.32 is lower.

The employee therefore receives:

£194.32 per week for weeks 7 to 39

Example with lower earnings

Now imagine the employee’s AWE is £180.

90% is:

£180 x 90% = £162

Compare:

• £162
• £194.32

£162 is lower.

The employee therefore receives:

£162 per week.

The statutory rate is a maximum during this part of SMP. It is not automatically the amount every employee receives.

Full maternity pay calculation example

Imagine an employee has AWE of £500.

For the first six weeks:

£500 x 90% = £450

£450 x 6 = £2,700

For the next 33 weeks:

90% of £500 is £450, which is higher than the statutory £194.32 rate.

So:

£194.32 x 33 = £6,412.56

Total SMP:

£2,700 + £6,412.56 = £9,112.56

The employee would therefore receive £9,112.56 in SMP over 39 weeks, before Income Tax, National Insurance and any other deductions that apply.

SMP is paid through normal payroll. For more information about deductions and reporting pay to HMRC, see Factorial’s guide to payroll.

How bonuses affect maternity pay calculation

Bonuses can have a noticeable effect on maternity pay because the calculation is based on earnings paid during the relevant period.

For example, imagine an employee normally earns:

£600 per week

But during the eight-week relevant period, they also receive a £2,000 bonus.

Their normal earnings over eight weeks would be:

£600 x 8 = £4,800

Add the bonus:

£4,800 + £2,000 = £6,800

Average weekly earnings:

£6,800 / 8 = £850

Their AWE for maternity pay could therefore be £850 rather than £600.

The first six weeks of SMP would then be:

£850 x 90% = £765 per week

Rather than:

£600 × 90% = £540 per week

That is a significant difference.

Always check whether a bonus or other payment counts as relevant earnings before completing the calculation.

How overtime and commission affect maternity pay calculation

The same principle can apply to overtime and commission.

If qualifying overtime or commission is paid during the relevant period and counts as earnings for Class 1 National Insurance, it will normally form part of the employee’s average weekly earnings.

For example:

Basic earnings over eight weeks:

£4,000

Overtime paid:

£400

Commission paid:

£600

Total relevant earnings:

£5,000

AWE:

£5,000 / 8 = £625

If you had only used basic pay, AWE would have been:

£4,000 / 8 = £500

That would make the first six weeks of maternity pay too low.

When payroll includes variable earnings, keeping employee and payroll information together can make these calculations easier. Factorial’s guide to HR and payroll software explains how connected systems can reduce duplicated information and payroll mistakes.

Salary sacrifice and maternity pay

Salary sacrifice can also change the average weekly earnings of the employee. HMRC normally calculates average weekly earnings using the pay the employee actually received and that was subject to National Insurance during the relevant period.

For example, imagine an employee’s contractual salary is £700 per week but they sacrifice £100 each week through a salary sacrifice arrangement.

If their relevant NI earnings are £600, maternity pay will generally be based on the relevant earnings actually paid rather than simply using the original £700 salary.

Statutory Maternity Pay itself cannot be salary sacrificed.

If an employee uses salary sacrifice, check the arrangement carefully before completing their maternity pay calculation.

What happens if the employee receives a pay rise?

A pay rise can mean you need to recalculate maternity pay, even after SMP has started.

HMRC says a qualifying pay rise between the start of the relevant period and the end of Statutory Maternity Leave can require you to recalculate average weekly earnings as though the higher pay had applied during the relevant period. You then pay any extra SMP you owe.

Example for SMP calculation with pay rise

Imagine an employee originally had AWE of:

£500

Their first six weeks of SMP were therefore:

£500 x 90% = £450

They later receive a backdated company pay rise that increases their recalculated AWE to:

£550

Their revised first-six-week rate becomes:

£550 x 90% = £495

Difference:

£495 – £450 = £45 per week

For six weeks:

£45 x 6 = £270

You may also therefore owe the employee an extra £270, as well as any difference that applies elsewhere in the calculation of their maternity pay. A pay rise can also sometimes make an employee eligible for SMP when their original earnings were too low.

How to calculate enhanced maternity pay

Some businesses offer enhanced maternity pay on top of the statutory minimum. Each employer can have a different policy for these situations, so there isn’t a standard formula to calculate enhanced maternity pay. Instead, we’ll look at a few examples of what this means so you understand how to work it out.

For example, your policy might offer:

• 12 weeks at full pay, followed by SMP
• 6 weeks at full pay, then 12 weeks at half pay, followed by SMP
• 26 weeks at full pay
• another company-specific arrangement

The important thing is to understand whether your enhanced pay is inclusive of SMP or paid on top of SMP.

Example 1: full pay inclusive of statutory maternity pay

Imagine an employee normally earns £700 per week.

Your policy gives them:

12 weeks at full pay, inclusive of SMP

They receive £700 in total each week.

You do not pay £700 plus SMP.

The SMP forms part of that £700 payment.

Example 2: contractual top-up

Another policy might say the employee receives statutory maternity pay plus a separate contractual top-up. If that is the case, payroll needs to calculate both of those things correctly.

Your maternity policy should make the method clear so SMP is not accidentally counted twice. If you want more information about creating and managing maternity policies, see Factorial’s Statutory Maternity Pay and Leave guide.

Using the GOV.UK maternity pay calculator

HMRC provides people in need with a maternity pay calculator that employers can use instead of calculating every date and figure manually.

Before starting, have the following information ready:

• the baby’s expected due date
• employee’s normal paydays
• their earnings during the relevant period
• and their planned maternity pay start date

The calculator can help identify the relevant dates and work out SMP. It is particularly useful when you are unsure which paydays belong in the relevant period.

However, unusual situations call for additional checks. For example:

• variable pay
• irregular pay periods
• salary sacrifice
• bonuses
• pay rises
• very early births

For more information about doing payroll, read our guide to calculating employee payslips.

Using last year’s maternity pay rate

Statutory rates normally change each tax year.

For 2026/27, the standard maternity pay rate is £194.32.

Factorial’s guide to PAYE rates and thresholds covers the main statutory payroll figures for the current tax year.

Maternity pay calculation checklist

Before sending the calculation to payroll, check:

1. Relevant period: Have you identified the correct paydays?
2. Relevant earnings: Have you included all qualifying earnings?
3. Bonuses: Were any qualifying bonuses paid during the period?
4. Overtime and commission: Have these been included where required?
5. AWE: Have you calculated average weekly earnings correctly?
6. Weeks 1 to 6: Have you calculated 90% of AWE?
7. Weeks 7 to 39: Have you used £194.32 or 90% of AWE, whichever is lower?
8. Pay rises: Has a later pay increase changed the calculation?
9. Salary sacrifice: Have you used the correct NI earnings?
10. Enhanced pay: Have you applied your company policy correctly?
11. Tax year: Are you using the correct statutory rate?
12. Payroll: Have you sent the final figures to payroll?

If you need information beyond the calculation itself, Factorial’s Statutory Maternity Pay and Leave guide covers eligibility, leave entitlements, employer responsibilities, statutory pay recovery and maternity records.

Calculate and manage maternity pay with Factorial

Accurate maternity pay calculations rely heavily on the information you hold across your HR and payroll tools. This includes earnings, bonuses, changes in pay and your employees’ recorded absences. Factorial is an AI business management platform that helps you collect all of that and keep employee, leave, and payroll information together, making it easier for HR, finance, and even IT teams to work from the same information and reduce the amount of paperwork you do each day. Request a demo of Factorial to see how it works and get a tailored quote for your organisation.