Pregnancy Due Date & Gestational Age Calculator
Find out when your baby is due and exactly how far along you are today. Enter the first day of your last period, your conception date, or an ultrasound measurement, and this free calculator estimates your due date, your gestational age in weeks and days, your current trimester and a countdown to delivery. It uses Naegele's rule — 280 days from the last menstrual period — and lets you adjust for a longer or shorter cycle. Everything runs in your browser, so your dates are never uploaded.
Pick the date you know best. LMP is the most common starting point.
The first day of your last menstrual period.
Optional. Leave blank for the standard 28-day cycle; a longer cycle shifts the due date later.
The estimated day of conception or ovulation.
The date the scan was performed.
The weeks and days the sonographer measured (e.g. 12 weeks 3 days).
Adds 543 years to displayed dates. Calculations are unchanged.
Your due date will appear here
Enter a date to estimate your due date and gestational age.
Estimated due date Estimated date of delivery, 40 weeks (280 days) from the first day of your last period.
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Gestational age How far along you are today, counted in completed weeks and days since your last period.
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Trimester First: weeks 0–13. Second: weeks 14–27. Third: week 28 to birth.
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Pregnancy progress
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Pregnancy details
This is an estimate based on average pregnancy length. Only about 5% of babies arrive on their exact due date. Always follow the due date confirmed by your doctor or midwife.
How to use
- Choose whether to calculate from your last period, conception date or ultrasound.
- Enter the relevant date; for an ultrasound, add the weeks and days measured at the scan.
- Optionally set your average cycle length if it differs from 28 days.
- Read your estimated due date, gestational age and current trimester instantly.
- Check the progress bar and countdown, then copy the summary to share.
Features
- Three calculation methods: last period, conception date, or ultrasound scan
- Cycle-length adjustment for cycles shorter or longer than 28 days
- Gestational age shown in completed weeks and days, with the current trimester
- Visual progress bar across all three trimesters plus a countdown to your due date
- Buddhist-era (B.E.) date display for Thai users
- 100% in-browser — your dates never leave your device