The earliest you can start maternity leave is 11 weeks before the expected week of childbirth — not 11 weeks before your due date. Those are different dates, often by several days, and getting them confused is the single most common error in this calculation. Give the calculator your due date and it works out every date that follows from it: when you can start, the week you must have told your employer by, when the 90% pay drops to the flat rate, when pay stops, and when your leave ends.
Maternity leave date calculator
Enter your due date. Everything below is worked out from the expected week of childbirth, as the law requires, and every step is shown.
This covers Statutory Maternity Leave and Statutory Maternity Pay in Great Britain. It does not cover Shared Parental Leave, adoption, surrogacy, or Maternity Allowance for the self-employed. An enhanced company scheme may be more generous than the statutory minimum shown here — check your contract. Everything runs in your browser; nothing is sent to us or stored.
The expected week of childbirth, and why it changes the answer
Nearly every date in maternity law counts from the expected week of childbirth — the Sunday-to-Saturday week your due date falls in — rather than from the due date itself.
If your due date is a Sunday the two are the same. Any other day and they differ, by up to six days. A Saturday due date puts the start of the expected week six days earlier, and every downstream date moves with it.
This matters because several widely-used calculators subtract 11 weeks from the due date instead. They will hand you a start date up to six days later than the law actually allows. If you have ever had a maternity leave form queried for starting “too early”, this is very often the reason — you were right and the form was checked against the wrong arithmetic.
The dates that follow from your due date
| Date | How it is worked out |
|---|---|
| Expected week of childbirth (EWC) | The Sunday-to-Saturday week containing your due date |
| Qualifying week | The 15th week before the EWC |
| Notify your employer by | The end of the qualifying week |
| Earliest leave start | 11 weeks before the start of the EWC |
| Automatic trigger window | The 4 weeks before the EWC |
| 90% pay period | The first 6 weeks of pay |
| Ordinary Maternity Leave ends | 26 weeks after leave starts |
| Maternity pay ends | 39 weeks after pay starts |
| Leave ends | 52 weeks after leave starts |
What to pack: a practical hospital bag checklist
Once you have the dates above, packing the bag is usually the next thing on the list — and most people leave it later than they mean to. There is no single correct kit, and hospitals vary in what they provide, so treat this as a starting point rather than a requirement. The list below groups the things that come up most often: a few for you, a few for the baby.
For you
Recovery kit, and the small things that make a hospital stay more comfortable.
Maternity pads, 15 pack
Extra-absorbent postpartum pads. Most people pack more than they think they’ll need — a second pack rarely goes to waste.
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Seamless nursing bras, 3 pack
Wire-free and easy to nurse in, which matters more than looking smart in the first fortnight. Sizes run S–XXL.
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Lanolin nipple cream, 40ml
The one most people reach for if breastfeeding starts out sore. Doesn’t need wiping off before a feed.
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Insulated water bottle with straw, 950ml
A straw means you can drink lying down or with your hands full — worth more than it sounds during labour and the first feeds.
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Long phone charging cable, 3m
Hospital sockets are rarely next to the bed. The most commonly forgotten item on every hospital bag list, by some distance.
View on AmazonFor the baby
Newborn basics — sized 0–3 months, since you won’t know their actual size until they arrive.
Newborn outfit set, 0–3 months
A five-piece set covers the going-home outfit and a couple of spares — newborns go through more changes of clothes than expected.
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First vests, 3 pack
Soft cotton, made in Britain, and cheap enough that a second pack in the next size up is worth having ready at home.
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First sleepsuits, 2 pack
Cotton, machine washable, and easy to get on and off for the first few nappy changes on the ward.
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Muslin squares, 5 pack
For posseting, swaddling, or simply somewhere clean to put the baby down. You will use more of these than any other single item.
View on AmazonAs an Amazon Associate we earn from qualifying purchases. This is a starting point, not a required list — hospitals and personal preference both vary. Availability and links were checked on 15 August 2026 and can change. It costs you nothing extra.
Maternity leave and maternity pay have completely different rules
This trips up more people than the arithmetic does. They are two separate entitlements with two separate tests.
Statutory Maternity Leave is a day-one right. GOV.UK is unambiguous: “It does not matter how long you’ve been with your employer, how many hours you work or how much you get paid.” If you are an employee, you get 52 weeks. Start yesterday, you still get 52 weeks.
Statutory Maternity Pay is not. To qualify you must have been continuously employed by the same employer for at least 26 weeks continuing into the qualifying week — the 15th week before your expected week of childbirth — and earn on average at least £129 a week, which is the lower earnings limit for 2026/27.
So it is entirely possible to be entitled to a year off and nothing from your employer to fund it. If that is you, your employer must give you form SMP1 within seven days of deciding, and Maternity Allowance from the DWP may be available instead — paid at £194.32 a week or 90% of your earnings if lower, but without the six-week 90% opening period that SMP has. If you are self-employed the amount depends on your Class 2 National Insurance record and can be anywhere between £27 and £194.32 a week.
What you are actually paid, and when it changes
Statutory Maternity Pay runs for up to 39 weeks in two distinct phases (GOV.UK):
- Weeks 1–6: 90% of your average weekly earnings before tax, with no cap.
- Weeks 7–39: £194.32 a week, or 90% of your average weekly earnings if that is lower.
Six plus 33 makes 39. If you take the full 52 weeks of leave, the final 13 weeks are unpaid — a gap worth planning for, and one the calculator dates precisely so you can see when it starts.
Maternity pay is treated like wages, so tax and National Insurance come off it. The £194.32 rate took effect on 5 April 2026 and holds until the next uprating in April 2027. It is a small oddity of the payroll year that HMRC changes the maternity rate on the first Sunday in April, while every other statutory payment changes on the 6th.
If the baby comes early, or you go off sick
Two things start your leave whether you planned it or not.
An early birth. Leave begins the day after the baby is born, regardless of the date you had booked. The 52 weeks runs from there.
Pregnancy-related illness in the four weeks before your expected week of childbirth. If you are off work for a pregnancy-related reason during that window, maternity leave starts automatically — Acas puts the start at the day after the first day of absence in that period. The same trigger starts your maternity pay.
The calculator gives you that four-week window as actual dates, because it is the one period in the pregnancy where a single day off work has a consequence measured in weeks. Being off sick for an unrelated reason — a broken ankle, flu — does not trigger it.
Telling your employer: the deadline that actually binds
You must tell your employer by the end of the qualifying week — the 15th week before your expected week of childbirth. In practice that is a Saturday, roughly 25 weeks into the pregnancy, and it is earlier than most people expect.
You need to tell them the baby’s due date and when you want leave to start. Your employer then has 28 days to confirm your return date in writing. If you later want to change your start date you generally need to give 28 days’ notice; to change your return date you need eight weeks’ notice, which is why the calculator dates that deadline too — it lands much earlier than people assume.
The two weeks you cannot decline
Compulsory maternity leave is two weeks immediately after the birth, or four weeks if you work in a factory. It is not waivable, by you or your employer, however much you might want to go back.
Your holiday keeps building the whole time. Statutory annual leave accrues throughout all 52 weeks of maternity leave, and you cannot take it at the same time — so most people come back with a sizeable balance and a conversation to have about when to use it. If you work part time and want to check the figure your employer has given you, our part-time holiday entitlement calculator works it out pro rata.
You can also work up to 10 keeping-in-touch days during your leave without ending it or losing SMP for those weeks. They are optional on both sides: your employer cannot require them and you cannot demand them. Pay for KIT days is whatever you agree.
Frequently asked questions
When does maternity leave start?
At the earliest, 11 weeks before the start of your expected week of childbirth — the Sunday-to-Saturday week your due date falls in. It starts automatically the day after the birth if the baby arrives early, or if you are off with a pregnancy-related illness in the four weeks before that week.
Is it 11 weeks before my due date or 11 weeks before the expected week?
Eleven weeks before the start of the expected week of childbirth. Unless your due date falls on a Sunday, that is earlier than 11 weeks before the due date itself — by up to six days.
How long do I have to work somewhere to get maternity leave?
No time at all. Statutory Maternity Leave is a day-one right for employees. Maternity pay is different: that needs 26 weeks’ continuous employment running into the qualifying week, and average earnings of at least £129 a week.
When does the 90% maternity pay drop to the lower rate?
After six weeks. The first six weeks are 90% of your average weekly earnings with no cap; the remaining 33 weeks are £194.32 a week, or 90% of your earnings if that is lower.
By when must I tell my employer I am pregnant?
By the end of the qualifying week — the 15th week before your expected week of childbirth, which falls around 25 weeks into the pregnancy. You tell them the due date and your intended start date.
What happens if the baby is born before my leave was due to start?
Maternity leave begins the day after the birth automatically, and the 52 weeks runs from that point rather than from your planned date.
Information, not advice. This explains the statutory position in Great Britain and is not legal advice. Many employers offer enhanced maternity schemes that are more generous than the minimum described here, so check your contract. If something material turns on your dates, contact Acas on 0300 123 1100 (Monday to Friday, 8am to 6pm), your union, or an employment solicitor.
Correct as of 1 August 2026, current for 2026/27. Sources: GOV.UK — Maternity leave; GOV.UK — Maternity pay; GOV.UK — Eligibility; GOV.UK — Maternity Allowance; HMRC rates and thresholds 2026 to 2027; Acas — Maternity leave and pay. More date tools on our all calculators page.