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Pregnancy Test Calculator

Find the earliest reliable date to take a home pregnancy test based on your last period or estimated ovulation day. Three test windows are shown — pick the one that fits your patience.

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Enter a date to see when a pregnancy test will be accurate.

When to take a pregnancy test

Home pregnancy tests detect human chorionic gonadotropin (hCG), a hormone the body produces shortly after a fertilised egg implants in the uterus. hCG starts low and roughly doubles every 48 hours in early pregnancy — so the longer you wait after ovulation, the more reliable the test becomes.

The three test windows in our calculator:

  • Earliest (10 days post-ovulation): only with very sensitive early-response tests. Roughly 50–75% accurate. High false-negative rate — a negative here means very little.
  • Reliable for most tests (12 days post-ovulation): standard supermarket tests should work. Accuracy around 85–95%.
  • Highest accuracy (14 days post-ovulation = first day of missed period): almost all tests are >99% accurate. The smartest waiting point.

How to take a pregnancy test correctly

  1. Use first morning urine for the most concentrated hCG. Especially important if testing early.
  2. Read the instructions on your specific test. Some need a stream, others a cup. Some show results in 1 minute, others in 5.
  3. Set a timer. Reading too early can miss a real positive; reading too late can produce an evaporation line that looks like a faint positive.
  4. If unsure, retest in 48 hours. hCG roughly doubles every 2 days; if the first test was real, the second line should be clearer.
  5. Confirm with a healthcare provider. A positive home test should be followed up with a clinical blood test for confirmation and to start prenatal care.

False negatives and false positives

False negatives — meaning “you are pregnant but the test says no” — are common in early testing and almost always due to hCG levels still being too low. If your period is still missing a week after a negative test, test again.

False positives are rare. Possible causes: a recent very-early pregnancy loss (chemical pregnancy) that briefly raised hCG, fertility medications containing hCG, or (very rare) some ovarian conditions and certain cancers. If you get a positive test, the result is overwhelmingly likely to be real — a blood test at your provider’s office will confirm.

Frequently asked questions

How early can I take a pregnancy test?
Very sensitive home tests (e.g. First Response Early Result) can detect pregnancy from about 10 days after ovulation — roughly 5 days before your expected period. Accuracy at that point is around 50–75%. For >99% accuracy, wait until the first day of your missed period (14 days after ovulation in a 28-day cycle).
Why is the first morning urine recommended?
Overnight, your urine becomes more concentrated, which means a higher level of pregnancy hormone (hCG) per ml. Testing with the first morning urine gives the test the best chance of detecting hCG when levels are still low — especially when testing early.
What if I get a negative result but my period still hasn’t arrived?
Retest in 3–7 days. hCG levels roughly double every 48 hours in early pregnancy, so a test that came back negative early may turn positive within a week. If you’re more than 14 days past your expected period and still testing negative, see your healthcare provider — they can confirm with a blood test (which detects hCG earlier than urine tests) and investigate other causes if pregnancy is ruled out.
Can I get a false positive?
Rarely. False positives can occur from very recent pregnancy loss, certain fertility medications containing hCG, or some medical conditions. If you get a positive test, the result is overwhelmingly likely to be correct — but a follow-up visit with your healthcare provider will confirm it with a blood test.
Should I use a digital or strip test?
Both detect the same thing — hCG in urine — and both are highly accurate when used correctly. Digital tests show ‘Pregnant / Not Pregnant’ in words rather than lines, which is easier to read but less sensitive than the most sensitive strip tests. If testing early, choose a strip test labelled ‘early result’ with the lowest hCG detection threshold (often 10–25 mIU/mL).
What if my cycles are irregular?
Calendar-based prediction is less accurate for irregular cycles. The most reliable approach is to test 21 days after the last unprotected sex if you don’t know your ovulation date. By then, any pregnancy should produce enough hCG for a reliable test result.

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