Gestation Calculator

This calculator has been designed to give you an idea of the treatment options available to you*. If you decide to have an abortion with Marie Stopes UK, one of our nurses will give a more approximate gestation date during your appointment by way of a scan.
*Please note that this online calculator will only give you an estimated gestation based on the details you have provided.

Please select the first day of your last menstrual period.



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How do I use a home pregnancy test?

If you've had unprotected sex or your contraception has failed, you could be pregnant. A home pregnancy test can help you confirm this.

You can buy a home pregnancy test both on the high street or online. Your local pharmacy or supermarket will sell a range of reliable testing kits. Follow the instructions carefully though if you want a reliable result. You don't need to buy the most expensive kit. It's important to remember that result will not be reliable until about 3 weeks after you had unprotected sex, or after your period is due. If you have any doubts, repeat the test, contact your GP or visit a Marie Stopes clinic

After using the test, the result will either be:

  • NEGATIVE - you're not pregnant. However, if your period is late or you have pregnancy symptoms, you'll need to repeat the test after a week. 
  • POSITIVE -  you're pregnant. You now need to decide what to do. Other people/doctors/counsellors can help you make a decision by explaining your choices but in the end you must decide what YOU want. Your choices include keeping the baby, adoption, or abortion.

Different pregnancy tests show a positive or negative test in different ways so again be sure to read the instructions carefully. Bear in mind that you can't do a reliable pregnancy test until 2-3 weeks after you had unprotected sex.

If your pregnancy test result is positive, you may have mixed feelings. It's important to give yourself time to consider your situation and seek advice as soon as possible. It's also important to make the right decision for you; this might not be the decision your friends or family would make.

Try and talk it over with someone. If you feel unable to talk to friends or family, you can speak to a Marie Stopes UK counsellor, your GP, or if you're under 25 – a Brook Advisory counsellor. Marie Stopes United Kingdom takes your privacy seriously and any counselling conversations would be confidential.

Please note that as well as pregnancy, unprotected sex puts you at risk of sexually transmitted infections (STIs) such as chlamydia. You should visit your local genito-urinary medicine clinic (GUM clinic) or the Marie Stopes Central London Health Screening clinic for testing.