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Simple tools for the forty weeks.
Quick answers to the questions that have real answers: when you are due, how many weeks along you are, when your fertile window is, how long that contraction lasted. No account, no pop-ups, no app to install.
Start with your due date
All tools
Due Date Calculator
Estimate your due date from your last period or conception date.
Pregnancy Week Tracker
See where you are and what is happening, week by week.
Ovulation Calculator
Find your fertile window and likely ovulation day.
Contraction Timer
Time contractions and see the pattern as it develops.
Weight Gain Calculator
Recommended ranges based on pre-pregnancy BMI.
Baby Growth Percentile
Weight and length percentiles for babies up to 24 months.
Baby Name Generator
Filter names by gender, origin, first letter, and length.
Week by week
Forty guides, one for each week: how the baby is developing, what you may notice, and what is worth doing now.
How the due date is worked out
A pregnancy is dated from the first day of your last menstrual period, not from conception. That sounds odd, but it is the convention every clinician uses, because the date of your last period is something you are likely to know and the date of conception usually is not. It means you are counted as two weeks pregnant at the moment of conception.
From there, Naegele's rule adds 280 days to reach the estimated due date. Our calculator adjusts that for cycle length, because the standard 280 days assumes a 28-day cycle and ovulation on day 14. If your cycles run longer or shorter, the estimate shifts accordingly.
Why it is called an estimate
Only around one birth in twenty happens on the estimated due date. Most babies arrive in the two weeks either side of it, and a first-trimester ultrasound is a more accurate date than any calculator, because it measures the baby directly rather than inferring from a cycle. If your scan gives a different date, trust the scan.
When to stop calculating and call someone
These tools answer arithmetic questions. They cannot tell you whether something is wrong. Bleeding, severe pain, a change in the baby's movements, a fever, or a sudden headache with visual changes are all reasons to contact your midwife or doctor straight away rather than looking for reassurance online.
There is more detail in our guides, including when to go to hospital with contractions.