For the most reliable result, test on or after
Use first-morning urine for early tests, and follow the instructions on your test.
When is the best time to take a pregnancy test?
Home pregnancy tests detect hCG, a hormone made after implantation. Most tests are reliable from the first day of a missed period. Some sensitive tests can detect hCG a few days earlier, but an early negative result is less reliable, because hCG may not have risen enough yet.
How the calculator works
- From your last period: the most reliable day is the day your next period is due (first day of your last period + your cycle length). The earliest possible day is about 4 days before that.
- From the date of sex: the NHS advises testing at least 21 days after unprotected sex if you do not know when your period is due.
If your test is negative
If your period still has not started, test again in a few days to a week. If your periods are irregular or tests stay negative and your period does not come, talk to your doctor. If your test is positive, use our Due Date Calculator and contact your doctor or midwife.
Frequently asked questions
Can I get a false negative?
Yes, especially if you test too early, use diluted urine, or do not follow the instructions. Testing first thing in the morning helps.
Can I get a false positive?
It is rare. It can happen after a very early miscarriage, with some fertility medicines that contain hCG, or with a few medical conditions.
Is a blood test more accurate?
A blood test at a clinic can detect smaller amounts of hCG, so it can show a pregnancy a little earlier than most home tests.
Is my information saved?
No. The calculation runs in your browser and nothing is stored.
References
NHS: Doing a pregnancy test