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Pregnancy & Fertility

Due Date Calculator

Calculate your baby's due date from last period or conception date. Free due date calculator with trimester timeline and key milestones.

Due Date at a glance

Calculate your baby's due date from last period or conception date. Free due date calculator with trimester timeline and key milestones.

Calculate your due date

Your estimated due date

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Due date
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Current week
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Trimester
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Days remaining

About the Due Date Calculator

This calculator provides evidence-based targets and interpretation based on current nutritional science and dietary guidelines. The formulas and reference ranges used are drawn from authoritative sources including the National Academies of Sciences, Engineering, and Medicine (Dietary Reference Intakes), the USDA Dietary Guidelines for Americans 2025-2030, and peer-reviewed research published in journals such as the American Journal of Clinical Nutrition, the New England Journal of Medicine, and JAMA.

How this calculator works

The calculator uses validated formulas that account for individual factors such as age, sex, body weight, and activity level. The results are personalized to your inputs and include interpretation categories (low, normal, high) based on established clinical or nutritional reference ranges. Always interpret results in the context of your overall health, diet, and lifestyle, a single number rarely tells the full story.

Practical guidance

Use this calculator as a starting point for understanding your nutritional needs or health metrics. The results are educational, not diagnostic, always discuss significant findings with your healthcare provider before making changes to your diet, supplement regimen, or medication. For best results, recalculate periodically as your body composition, activity level, or health status changes. Track trends over time rather than focusing on single measurements, as day-to-day variation is normal and expected.

Evidence base and limitations

All nutritional targets are based on population-level recommendations that apply to most healthy individuals. Individual needs may vary based on genetics, medical conditions, medications, pregnancy, lactation, and other factors. The calculators do not replace professional medical or nutritional advice. If you have a chronic health condition, are pregnant or breastfeeding, or take medications that affect nutrient metabolism, consult a registered dietitian or physician for personalized guidance.

Editorial and formula review
Formulas verified against published peer-reviewed sources Last verified

Formula sources, population limits, and references for this pregnancy calculator are documented in our public methodology. Read the methodology · Medical disclaimer

Frequently asked questions

Naegele's rule is accurate to within 7-10 days for women with regular 28-day cycles. An early ultrasound is more accurate.
Sometimes. If an early ultrasound differs significantly from your LMP-based due date, your doctor may adjust it.
With irregular cycles, an early ultrasound is the most accurate way to date the pregnancy.
Only about 5%. About 50% are born within a week of the due date.
37 weeks is considered "early term." Full term is 39-40 weeks.