Due Date Calculator
Estimate pregnancy due date based on last menstrual period (LMP) or conception date. Due dates are estimates. Ultrasound dating and clinical guidance may be more accurate depending on timing and individual factors.
Inputs
Used for a simple due date adjustment vs a 28-day cycle.
days
Results
Estimated due dateOct 22, 2026
Estimated conceptionJan 29, 2026
Gestational age (today)0w 0d
Cycle length used: 28 days
Due dates are estimates. Confirm with a healthcare professional.
How to use it
- Choose LMP-based or conception-based method.
- Enter the relevant date (LMP or conception date).
- If using LMP, optionally enter average cycle length for a simple adjustment.
- Review the estimated due date and gestational age estimate.
Key formulas
- LMP-based estimate (rule of thumb)
- EDD ≈ LMP + 280 days (+ adjustment for cycle length)
- Conception-based estimate (rule of thumb)
- EDD ≈ conception + 266 days
FAQ
LMP-based dating assumes a typical cycle and ovulation timing. Conception-based dating uses an estimated fertilization date. Ultrasound is often used clinically to refine estimates.
If your cycles are longer or shorter than 28 days, ovulation may occur later or earlier. Some calculators adjust EDD by (cycleLength − 28) days as a rough approximation.
No. Many pregnancies do not deliver on the exact due date. The due date is a planning estimate.
If you have an estimated conception date, you can use that method. Otherwise, clinical dating (often ultrasound) is commonly used.
No. For pregnancy care, rely on your healthcare provider for dating and guidance.
Sources
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Disclaimer
For informational purposes only and not medical advice. Due date estimates vary and should be confirmed with a healthcare professional.