Maternity Leave Date Calculator
Plan maternity leave around your due date — US FMLA (12 weeks), UK statutory maternity leave (52 weeks, earliest start 11 weeks before the due week) or your own scheme: start date from weeks before the due date or a date you pick, last day, return-to-work date, notice deadlines, the UK qualifying week, SMP and compulsory-leave dates, holiday added at the end, and what changes if the baby comes early.
How it works
start = due date − 7 × weeks before (or the date you pick, never before the earliest allowed start, or the day after an earlier birth); end = start + 7 × weeks − 1 day; return = end + 1 day (+ holiday working days); UK: due week = Sunday–Saturday week containing the due date, earliest start = that Sunday − 11 weeks, qualifying week = 15th week before it, leave up to 52 weeks (26 ordinary + 26 additional), SMP 39 weeks; US FMLA: 12 weeks, 30 days’ notice, bonding leave within 12 months of the birth
Most schemes let you choose when leave begins within a window before the due date and count the total from that start, so every week taken before the birth is one fewer afterwards. In the UK, statutory maternity leave lasts up to 52 weeks (26 weeks of Ordinary and 26 of Additional Maternity Leave). It can start any day from the beginning of the 11th week before the expected week of childbirth — the Sunday-to-Saturday week containing the due date — and you must tell your employer by the end of the 15th week before that week, which is also the qualifying week for Statutory Maternity Pay. Leave starts automatically if you are off sick with a pregnancy-related illness in the 4 weeks before the due week, or the day after the birth if the baby comes first. In the US, the Family and Medical Leave Act gives eligible employees 12 weeks of unpaid, job-protected leave in a 12-month period, with 30 days’ notice when the leave is foreseeable; leave to bond with the baby must be used within 12 months of the birth, and state or employer schemes often run at the same time. Choose Custom to enter any other scheme’s length and earliest start. You can set the start as weeks before the due date or as a calendar date, add holiday or PTO at the end, and record an early birth under More options. Confirm the dates with your employer or HR.
Worked example
Due 15 January 2027, starting 2 weeks early with 26 weeks of leave (Custom): leave runs Friday 1 January to Thursday 1 July 2027, back at work Friday 2 July, with 24 weeks after the due date. Under UK rules the due week runs Sunday 10 to Saturday 16 January, so the earliest start is Sunday 25 October 2026, the employer must be told by Saturday 3 October 2026 (the end of the qualifying week, 27 September – 3 October), and 52 weeks from 1 January ends on Thursday 30 December 2027. Under FMLA the same start gives 12 weeks to Thursday 25 March 2027, back on Friday 26 March, with notice due by 2 December 2026.
Sources: GOV.UK — Maternity pay and leave: leave · GOV.UK — How to claim maternity leave (notice rules) · US Department of Labor — Family and Medical Leave Act · 29 CFR 825.302 — FMLA notice for foreseeable leave
Frequently asked questions
What if the baby arrives early?
In the UK and most other schemes, leave begins the day after the birth if that is earlier than your planned start, and the total is unchanged. Turn on “The baby has already arrived” under More options and enter the birth date to see the new dates.
How early can maternity leave start?
In the UK, from the start of the 11th week before the expected week of childbirth. FMLA has no fixed earliest date: it can cover prenatal care or time you cannot work because of the pregnancy, but those weeks come out of the 12. Other countries set their own window; use Custom.
How long is maternity leave under FMLA?
Twelve workweeks of unpaid, job-protected leave in a 12-month period, if you have worked for the employer for 12 months and 1,250 hours and the site has 50 or more employees within 75 miles. Many states and employers add paid leave, which often runs at the same time.
When do I need to tell my employer?
UK: by the end of the 15th week before the expected week of childbirth, giving the due date and the date you want to start; changing the start needs 28 days’ notice, and returning before the end of 52 weeks needs 8 weeks’ notice. US FMLA: 30 days before foreseeable leave, or as soon as practicable.
Can I add holiday to the end of my maternity leave?
Often yes — in the UK you keep accruing annual leave during maternity leave, and many people take it straight afterwards. Enter the number of working days under More options and the return date moves past them, skipping weekends.
Related calculators
Dates are a planning estimate. Check your entitlement, notice rules and dates with your employer or HR and the official rules for your country or state.