Pregnancy & baby calculators
Pregnancy and baby calculators, made calm and clear
Small, focused tools for the questions that come up between appointments. Each one shows the formula behind the number, tells you where the guidance comes from, and keeps your dates on your own device.
Choose a tool
Due Date Calculator
Estimate your baby's due date from the first day of your last period, then see your current pregnancy week, trimester and upcoming milestone dates. Includes a shareable result card.
Open tool →Ovulation Calculator
Estimate your ovulation day, your seven-day fertile window and your two peak fertility days from your cycle length, with the assumptions spelled out.
Open tool →Conception Date Calculator
Work out when you most likely conceived, from your last period or from a due date you already know, and see the week your pregnancy is dated from.
Open tool →Implantation Calculator
See the six-to-twelve-day implantation window after ovulation, the most likely day, and the earliest sensible day for a pregnancy test.
Open tool →hCG Doubling Calculator
Compare two hCG results taken at known times and see the interval, the doubling time and the rise projected over 48 hours, with the ACOG lower limit explained.
Open tool →Contraction Timer
Time each contraction, see how long it lasted and how far apart they are, and keep a record you can describe to your midwife.
Open tool →Corrected Age Calculator
Work out a premature baby's corrected age from their birth date and gestational age at birth, alongside their chronological age.
Open tool →IVF Due Date Calculator
Estimate a due date from an embryo transfer date and stage, for day 5 blastocysts and day 3 cleavage-stage embryos.
Open tool →Baby Percentile
See how your baby's weight and length compare with growth chart percentiles for their age and sex.
Guides & data
Reference tables for the questions that need a number rather than a calculator. Every range is copied from public guidance, labelled with its source, and dated so you can see when it was last checked.
Pregnancy Week Tracker (Printable)
A free two-page PDF covering all 40 weeks: dates, appointments, symptoms and notes, sized for a home printer.
Download free PDF →Pregnancy Weight Gain Chart
Recommended total weight gain by pre-pregnancy BMI for one baby or twins, plus the weekly rate for the second and third trimesters.
View chart →Baby Feeding Chart by Age
Feeds per day, formula amounts per feed and daily totals from birth to 12 months, with breast milk and formula kept separate.
View chart →Baby Sleep Schedule by Age
Total sleep in 24 hours, night sleep and nap ranges from birth to two years, and an honest note on wake windows.
View chart →How these tools are built
Three rules apply to every calculator on Early Pregnancy Tools.
- Free, no account No email required, no sign-up, no paywall, no ads to dismiss before you get an answer.
- Private by design Everything runs in your browser. The dates you type are never sent to a server or stored anywhere.
- Sourced, not guessed Each tool explains its formula in plain English and cites public guidance from the NHS and ACOG. These tools are educational and never a substitute for medical advice.