Pregnancy calculators
Here you have all the pregnancy calculators in one place. They are guidance tools to help you answer the most common questions: how many weeks pregnant you are, when your estimated due date is, which your fertile days are, or how many months your weeks equal. Remember they are for guidance only and never replace the advice of your doctor or midwife.
Pregnancy calculators
How many weeks pregnant am I? Calculate it step by step
How many weeks pregnant am I? Learn to work it out from your last period with our calculator, step by step…
Missed Period: How Many Days Late Before You Take a Test
How many days late is normal, when to take a pregnancy test and what a negative result really means. Causes and when to see a doctor.
When to Take a Pregnancy Test: Calculator by Scenario
Work out when to take a pregnancy test after sex, after ovulation or after a missed period, with a scenario calculator and day-by-day timing.
![Online gestogram: pregnancy wheel and due date [Calculator]](/img/300_Test-de-embarazo-Online-Gestograma.jpg)
Online gestogram: pregnancy wheel and due date [Calculator]
Spin the online gestogram with your last period and find your pregnancy week, trimester and estimated due date. Free, no downloads.
Conception date calculator: when did I conceive
Wondering when you might have conceived? I explain how to estimate it from your last period, your due date or your week of pregnancy…
Implantation calculator: when the embryo implants
When does the embryo implant and when can a test turn positive? Work out your likely implantation window with my free calculator.
Pregnancy weight gain: how much is normal by BMI
How much weight should you gain in pregnancy? Work out your recommended range by BMI, trimester by trimester, and what's normal.
Fertility calculator: fertile days and when you ovulate
Calculate your fertile days and ovulation date with our ovulation calculator. Symptoms, how to use an ovulation test and when your…
Weeks to months of pregnancy: calculator and full table
Convert your pregnancy weeks into months with this calculator. Complete weeks-to-months table…
Beta-hCG: what it is, levels by week and what they mean
Got a beta-hCG blood test and no idea what your number means? I explain what it is, typical levels by week…
Online tests and games
Which one do you need?
Each tool answers a different question, and most of them need just one starting date. If you don't have it to hand, begin with the first day of your last period: the others build on it.
- How many weeks pregnant am I: takes your last period and tells you your week and day.
- Gestogram: the classic wheel. Works out your due date and places you in the corresponding week.
- Conception date: if you know roughly when you ovulated, it estimates the day you conceived.
- Implantation calculator: estimates when the embryo may have implanted after fertilisation.
- Fertile days: this one runs backwards. It's for before pregnancy, to find your ovulation window.
- Weeks to months: converts your pregnancy weeks into months so you can follow the conversation.
- Beta-hCG: helps you read this hormone's values week by week.
- Weight gain: shows how much weight is recommended based on your pre-pregnancy BMI.
They're all for guidance and they work just as well on a phone. If a result doesn't match what your doctor says, go with your doctor: no calculator can see your individual case.
Frequently asked questions
How is the due date worked out?
Take the first day of your last period and add 40 weeks (Naegele's rule). It's an estimate: only a small share of babies arrive exactly on that date, which is why it's called an "estimated" due date.
Why doesn't it match my scan?
Because a scan measures the baby and adjusts the date to its size, while the calculator works from dates. When the two differ, the first-trimester scan usually wins. It's normal and it doesn't mean anything is wrong.
Do they work if I conceived through IVF?
In that case the transfer date is more reliable than your period. Most calculators don't cover that scenario, so use whatever date your clinic gives you.
Is anything I type stored?
No. The calculation runs in your own browser, and the figures you enter aren't sent or saved anywhere. There's nothing to sign up for.
These calculators are for guidance only. If you are pregnant or have any doubts about your pregnancy, always talk to your doctor or midwife.