Pregnancy Due Date Calculator
Plan every trimester with confidence. Enter the first day of your last menstrual period and your average cycle length to see an estimated due date, pregnancy progress, and key milestones.
- Adjusts for custom cycle length between 20 and 45 days.
- Instant trimester timeline and milestone overview.
- Built by SnooBu to complement your pregnancy and baby tracking experience.
Free Pregnancy Due Date Calculator
Welcome to SnooBu's growing toolkit for parents and parents-to-be. Start with our due date calculator, explore milestone guidance, and get a feel for the supportive planning you can expect inside the SnooBu app.
Personalised timeline
See trimester transitions, milestone checkpoints, and your estimated due date adjusted to your cycle length.
Science-backed guidance
Based on the standard 280-day gestation while factoring in your unique cycle to keep predictions grounded and relevant.
Designed for real life
Export insights into your SnooBu app flow, sync reminders, and share updates with your support team.
How the SnooBu due date calculation works
We use Naegele's rule -- the clinical standard for estimating pregnancy timelines. That means adding 280 days to the first day of your last menstrual period. Because cycles vary, we adjust this baseline to reflect the average length of your cycle so the predicted ovulation window matches your biology.
The calculator immediately reveals your current trimester, remaining days, and a milestone roadmap so you can plan appointments, celebrate progress, and prepare your support network. It is a perfect companion to the SnooBu app where you can log symptoms, insights, and daily tasks.
Remember: every pregnancy is unique. Ultrasounds, provider guidance, and your personal medical history are critical when refining your official due date.
Pregnancy calculator FAQ
How does the due date calculator work?+
We start with the first day of your last menstrual period and add 280 days, which is the average length of pregnancy. If your cycle length is longer or shorter than 28 days we adjust the calculation so it reflects your typical ovulation window.
Can I rely on the due date from this calculator?+
Due dates are predictions, not guarantees. Only about five percent of babies arrive on their exact estimated date. Use this tool for planning and discussion, and always confirm milestones with your healthcare provider.
What if I know my conception or ovulation date?+
Ovulation typically happens around 14 days before your expected period. If you know your exact conception date, count 266 days from it to estimate delivery, or enter the equivalent last period date in this tool.
Will more tools be added here?+
Yes. This page is the home for SnooBu's free pregnancy and baby planning tools. We're already working on growth charts, feeding schedules, and downloadable templates.
Explore more tools
Discover our baby name generator and other helpful tools for your pregnancy journey.