Pregnancy Tools
Due Date Calculator — Estimated Delivery Date
Estimate baby due date from last period or conception date using Naegele-style calendar math. Free, educational, not medical advice.
Pregnancy Due Date Calculator on FYN Tools is a free Pregnancy Tools utility. Open Pregnancy Due Date Calculator in your browser — no signup required. Choose LMP or conception date; the tool adds 280 days (LMP) or 266 days (conception) to show your estimated due date, current week (1–40), and trimester end dates. Related: Pregnancy Week Calculator.
Privacy & processing: EDD is an estimate — only about 5% of babies arrive on the exact date. Confirm with prenatal care.
TL;DR: Choose LMP or conception date; the tool adds 280 days (LMP) or 266 days (conception) to show your estimated due date, current week (1–40), and trimester end dates.
Reviewed by FYN Tools Editorial · Guides ·
Data input / output
| Inputs | Last menstrual period (LMP) date OR conception date — toggle with the mode buttons |
|---|---|
| Outputs | Estimated due date, current pregnancy week, trimester 1 and 2 end dates |
| Formats | Calendar date picker |
| Limits | Calendar estimate only — ultrasound dating may differ; not medical advice |
| Processing | Client-side (browser) |
How to Use the Pregnancy Due Date Calculator
- Tap Use Last Period (LMP) or Use Conception Date.
- Pick the date from the calendar picker.
- Read the estimated due date and current pregnancy week.
- Note trimester 1 and 2 end dates for planning discussions.
- Share the estimate with your prenatal clinician — they may adjust after ultrasound.
What is a Pregnancy Due Date Calculator?
Pregnancy Due Date Calculator: Estimates EDD from LMP using Naegele-style dating — only ~5% of births land on the exact day.
Inputs: First day of last period, cycle length if asked. Outputs: Estimated due date and gestational week. Mistake to avoid: ignoring a dating scan that disagrees with LMP.
Pregnancy Due Date Calculator: Estimates EDD from LMP using Naegele-style dating — only ~5% of births land on the exact day.
How it works
In LMP mode the tool adds 280 days to your last period start (Naegele rule). In conception mode it adds 266 days. It also calculates weeks pregnant from today and trimester boundary dates.
Explore more tools on our site.
Usage scenarios
- LMP due date: Pick last menstrual period and get an EDD plus trimester dates in one pass.
- Known conception date: Switch to conception mode when LMP is uncertain.
- Week count for appointments: Read gestational week from the same card before you see a clinician.
Input / Output Examples
Input
LMP: 1 Jan 2026
Output
EDD ≈ Oct 2026 · trimester markers
Input
Conception mode with known date
Output
Due date from conception instead of LMP
Frequently Asked Questions
Is the due date calculation exact?+
It provides a reliable estimate based on standard pregnancy timelines. Actual delivery may vary.
What if I know my conception date?+
Select the conception option to calculate a due date based on that date.
Does this replace medical advice?+
No. Always confirm due dates with your healthcare provider.
Is my data saved?+
No. All calculations happen in your browser.
Key Features
- LMP or conception date modes
- 280-day / 266-day calendar math
- Current pregnancy week (1–40)
- Trimester 1 and 2 end dates
- Medical disclaimer on page
Benefits
Pregnancy Due Date Calculator runs without installing desktop software
Accepts: First day of last period, cycle length if asked
Returns: Estimated due date and gestational week
When to Use Pregnancy Due Date Calculator
- When you need estimates EDD from LMP using Naegele-style dating — only ~5% of births land on the exact day. without another app
- When your input looks like: First day of last period, cycle length if asked
Advantages
- Pregnancy Due Date Calculator runs without installing desktop software
- Accepts: First day of last period, cycle length if asked
- Returns: Estimated due date and gestational week
- How-to and FAQs for Pregnancy Due Date Calculator live on the same page
Tips
- Read the Privacy & processing note before you paste secrets.
- Ignoring a dating scan that disagrees with LMP.
- Contact a clinician if symptoms are severe or unusual — online tools cannot triage emergencies.
Common Mistakes
Ignoring a dating scan that disagrees with LMP.
Treating one run as final without checking units or a second sample.
Ignoring related tools when the next step is resize, compress, or convert.
Summary
Use Pregnancy Due Date Calculator on this page, then browse related pregnancy tools linked below.