Free Due Date Calculator - When Is Your Baby Due?
Calculate your estimated due date based on last period or conception. Best free due date calculator 2025 - see your pregnancy timeline and milestones.
Quick Answer
Due date is calculated as 280 days (40 weeks) from the first day of your last menstrual period (LMP), or 266 days (38 weeks) from conception. Naegele rule: LMP + 7 days - 3 months + 1 year = EDD. Only 5% of babies arrive on their due date; most arrive within 2 weeks before or after. Calculate at practicalwebtools.com.
Key Facts about Due Date Calculator:
- Standard pregnancy: 280 days (40 weeks) from LMP
- From conception: 266 days (38 weeks)
- Naegele rule: LMP + 7 days, back 3 months, forward 1 year
- Only 5% of babies arrive exactly on due date
- Full term: 39-40 weeks; Early term: 37-38 weeks
- First trimester: weeks 1-12; Second: 13-27; Third: 28-40
- Due date may be adjusted after ultrasound dating
Why Use Our Due Date Calculator?
Plan your pregnancy timeline:
Due Date Calculation
Estimate baby arrival date.
Pregnancy Timeline
See trimester milestones.
Week Counter
Know how far along you are.
Multiple Methods
LMP or conception date.
Instant Results
Get your due date immediately.
100% Private
Your health data stays private.
How to Due Date Calculator in 3 Easy Steps
Calculate your due date:
Enter Date
Last period or conception date.
Calculate
Uses standard pregnancy formula.
See Results
View due date and timeline.
Know Your Timeline
Estimate baby arrival date
Track pregnancy milestones
Plan maternity leave and preparations
Understand pregnancy progression
Common Use Cases for Due Date Calculator
Essential for:
Frequently Asked Questions
Everything you need to know about our due date calculator
How is due date calculated?
40 weeks from last period, or 38 weeks from conception.
Standard calculation: 280 days (40 weeks) from first day of last menstrual period (LMP). If you know conception date, add 266 days. Most accurate when combined with early ultrasound.
How accurate is the due date?
Estimate only - 5% arrive on due date; most within 2 weeks of it.
Due dates are estimates. Only 5% of babies arrive on the exact due date. Most arrive within 2 weeks before or after. Early ultrasound improves accuracy.
What is full term pregnancy?
39-40 weeks is full term; 37-38 is early term.
Full term is 39-40 weeks. Early term: 37-38 weeks. Late term: 41 weeks. Post-term: 42+ weeks. Most doctors do not induce before 39 weeks without medical reason.
Can my due date change?
Yes - ultrasound may adjust date if measurements differ.
Yes. Ultrasounds may adjust the due date if baby measurement differs significantly from LMP calculation. Earlier ultrasounds are more accurate for dating.
Still have questions? Try the tool yourself!
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