Enter your timeline
Choose one method and enter the date. We use UTC dates to avoid daylight saving time drift.
Results
Enter your dates above and press calculate to see your estimated due date and milestones.
Please complete the highlighted fields and try again.
Estimated Due Date
Gestational age today
Equivalent dates
- Equivalent LMP:
- Equivalent conception:
Key milestones
- Start of 2nd trimester (14w0d)
- Start of 3rd trimester (28w0d)
- Early term (37w0d)
- Full term (39w0d)
- Late term (41w0d)
- Postterm (42w0d)
Milestone timing varies by clinical guideline and individual pregnancy factors.
For information only; not a medical diagnosis. Speak with your clinician for personalised guidance.
How to interpret the result
A due date is an estimate. Different input methods can give different answers because they anchor pregnancy timing differently.
Which method should I use?
- LMP (Last Menstrual Period) is common when you know the first day of your last period. Cycle length adjusts the assumed ovulation date.
- Conception / ovulation can be more direct if you tracked ovulation (for example, LH tests or basal body temperature).
- IVF / embryo transfer is often the most precise because transfer date and embryo age are known.
- Ultrasound works from the gestational age measured on the scan date and is often used clinically to confirm or revise dating.
Why cycle length matters (LMP mode)
The “40 weeks” rule assumes a 28-day cycle with ovulation around day 14. If your typical cycle is longer or shorter, the estimate shifts by roughly (cycle length − 28) days.
Mini examples
- Conception date known: enter the ovulation/conception day and the tool adds about 266 days (38 weeks).
- Ultrasound: if your scan says 12w3d on the scan date, we count forward to 40w0d.
- IVF day-5 transfer: enter the transfer date and embryo age 5 days; the tool accounts for embryo age when estimating the due date.
References
How to use this page effectively
This guide helps you use Due Date Calculator as a practical decision page: start with the key section, confirm assumptions, and use related links to move from overview to the exact tool or topic you need.
How it works
This page is designed as an orientation layer. It summarizes a topic, highlights the most common decision paths, and links to task-specific tools or deeper references. The best workflow is to read the short context first, choose one concrete objective, and then follow a single linked action path. By avoiding parallel jumps across many links, you reduce context switching and make results easier to reproduce.
When to use
Use this page when you are not yet sure which calculator or resource is the right fit, or when you need a quick map of related options before doing detailed calculations. It is particularly useful at the start of a task, during review meetings, and when onboarding teammates who need a clear sequence rather than isolated links.
Common mistakes to avoid
- Jumping directly to a random tool without confirming the page-level assumptions first.
- Opening many links at once, which makes it hard to compare methods consistently.
- Copying outputs without recording input assumptions, units, and interpretation context.
- Treating summary text as final advice instead of validating with the linked detailed tool.
Interpretation and worked example
A reliable pattern is: pick one objective, open one recommended link, run a baseline case, then return and choose only one follow-up branch. If your second branch gives a conflicting direction, go back to this page and compare assumptions (units, period, constraints) before deciding. This keeps decisions traceable and avoids hidden mismatches across pages.
See also
FAQ
How is the due date calculated?
From LMP we add 280 days (40 weeks). From conception or embryo transfer we add 266 days (38 weeks). From ultrasound we work backwards from the gestational age on the scan date.
Can I rely on this as medical advice?
No. Only a qualified healthcare professional can provide personalised medical advice. Use this tool as a planning guide and confirm all questions with your care team.
What should I do first on this page?
Start with the minimum required inputs or the first action shown near the primary button. Keep optional settings at defaults for a baseline run, then change one setting at a time so you can explain what caused each output change.
Why does this page differ from another tool?
Different pages often use different defaults, units, rounding rules, or assumptions. Align those settings before comparing outputs. If differences remain, compare each intermediate step rather than only the final number.
How reliable are the displayed values?
Values are computed in the browser and rounded for display. They are good for planning and educational checks, but for regulated or high-stakes decisions you should validate assumptions with official guidance or professional review.