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 can I test whether I'm pregnant?

If you've had unprotected sex or your contraception has failed, you could be pregnant. You may need to take a pregnancy test to confirm this.

If you've had unprotected sex within the last 5 days and a pregnancy would be unwanted, you can use emergency contraception such as the emergency contraceptive pill or IUD to ensure any pregnancy does not continue. If you've had unprotected sex more than 5 days ago, it's important to take a pregnancy test after about 3 weeks, if your period is late, or if you have abnormal bleeding. There are two ways of arranging a pregnancy test:

  • Attend a clinic for a test: pregnancy tests are available at Marie Stopes UK centres, some GPs, many family planning clinics and STI clinics (sexually transmitted infection clinics).
  • Purchase a home pregnancy test: you can buy a home pregnancy test – pharmacies and supermarkets sell a range of reliable testing kits. Follow the instructions carefully though if you want a reliable result. Read How do I use a pregnancy test? for more advice.

The result will either be:

  • NEGATIVE - you’re not pregnant. If your test is negative, but your period is late or you have pregnancy symptoms, you need to repeat the test after a week.
  • POSITIVE - you're pregnant. 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.

Bear in mind that you cannot do a reliable pregnancy test until 2-3 weeks after the time when you may have become pregnant.

If you've had a positive pregnancy test, you may be feeling confused, shocked, and scared. It's important to face what's happening and seek advice as soon as possible. It's also important to make the right decision for you, and this might not always 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 aged under 25 – a Brook Advisory counsellor. Marie Stopes United Kingdom takes your privacy seriously and any counselling conversations would be confidential. Read about our counselling services.

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.