Maternity Leave Date Calculator
Updated August 2026 · Free · No sign-up
Plan your maternity leave dates — work backwards from your due date to the last working day, leave start, return date, and the notification deadlines for FMLA (US) and statutory leave (UK).
Quick answer: Enter your due date and planned leave length: the calculator returns your last working day, leave start, and return date. Typical patterns: US — 2 weeks before due date + 12 weeks FMLA; UK — leave can start 11 weeks before the due date, up to 52 weeks total.
The Dates That Matter
- Leave start = due date − weeks before.
- Last working day = the working day before leave starts.
- Return date = leave start + leave length.
- Notification deadlines: US FMLA — 30 days before foreseeable leave; UK — by the 15th week before the expected week of childbirth (~week 25 of pregnancy) for both leave and SMP.
Worked Example
Due date November 20, starting leave 2 weeks before, 12 weeks total: leave starts November 6, last working day November 5 (or the Friday before if it lands on a weekend), return January 29. FMLA notice due by early October.
US Planning Notes
| Item | Detail |
|---|---|
| FMLA | 12 weeks job-protected, unpaid — birth + bonding share the same 12 weeks |
| Short-term disability | Typically pays 6 weeks (vaginal) / 8 weeks (C-section) at 50-70% |
| State paid family leave | CA, NY, NJ, WA, MA, CO, OR, CT and others: 6-12 paid weeks at 60-90% |
| PTO stacking | Employers may require or allow PTO to run concurrently — ask which |
| Timing strategy | Disability covers the birth weeks; bonding weeks can often be taken later in the first year, including intermittently where allowed |
UK Planning Notes
52 weeks total (26 ordinary + 26 additional), of which 39 are paid via SMP: 90% of average earnings for 6 weeks, then the statutory flat rate. Leave can begin any time from 11 weeks before the expected week — and starts automatically if you're off sick with a pregnancy-related illness in the last 4 weeks. Two weeks after birth are compulsory leave (4 for factory workers). "Keeping in touch" days: up to 10 paid days without ending leave. Run the money side in the maternity pay calculator and check holiday accrual — annual leave keeps accruing through all 52 weeks.
Deciding When To Start
- Working close to the due date maximizes post-birth weeks — the trade most parents in 12-week systems make; roughly 1 in 4 first babies arrives before 39 weeks, so have a same-day handover plan.
- Starting 4-6 weeks early suits physically demanding roles, long commutes, complications, or simply wanting the buffer — at the cost of post-birth weeks unless your system (UK) is long enough not to care.
- Split strategies: where bonding leave can be deferred (US FMLA within 1 year; UK shared parental leave blocks), taking a later block when the other parent returns to work often beats one continuous run.
The Return-Date Conversation
Book the return date with your manager in writing when leave starts, and know the change rules: UK requires 8 weeks notice to change a return date; US practice varies by employer. Phased returns (3-4 day weeks initially) are increasingly standard — in the UK you have a statutory right to request flexible working from day one of employment. Returning part-time? Recompute salary with the pro-rata calculator and PTO with the accrual calculator.
Frequently Asked Questions
When should I start maternity leave?
Most start 0-2 weeks before the due date to maximize post-birth time; physically demanding roles or complications favor 4-6 weeks early. UK leave can start up to 11 weeks before.
How do I calculate my return date?
Leave start date + leave length. Starting Nov 6 for 12 weeks returns Jan 29. Book it in writing and know the notice rules for changing it (UK: 8 weeks).
When must I tell my employer?
US FMLA: 30 days before foreseeable leave. UK: by the 15th week before the expected week of childbirth (~week 25) for both leave and SMP.
Is maternity leave paid in the US?
FMLA is unpaid; pay comes from short-term disability (6-8 weeks at 50-70%), state paid family leave programs (where available), and PTO stacking.
How long is UK maternity leave?
52 weeks (26 ordinary + 26 additional); 39 weeks paid — 90% of earnings for 6 weeks, then the statutory flat rate. Two weeks post-birth are compulsory.
Does annual leave accrue during maternity leave?
UK: yes, through all 52 weeks including bank holidays — many parents append accrued holiday to extend paid time. US: per employer policy.
✓ Formula verified • Last updated: August 20, 2026