GUIDE
Home pregnancy tests are over 99 percent accurate when taken on or after the day of a missed period with first-morning urine. Most errors are false negatives caused by testing too early.
Understanding what affects accuracy — hCG levels, test sensitivity, timing, and user error — helps you trust your result and know when retesting is warranted.
Be prepared from day one
Manufacturers cite over 99 percent accuracy, and this is true under ideal conditions: testing on or after the day of a missed period, using first-morning urine, and following the instructions exactly. In real-world use, accuracy is still very high but can dip when people test early or use dilute urine.
The most important factor in accuracy is timing. At 8 days past ovulation, even the most sensitive tests detect pregnancy less than 25 percent of the time. By 14 DPO (the day of a missed period), detection rates exceed 95 percent. For a detailed breakdown of when to test, see our guide on when to take a pregnancy test.
False negatives are almost always a timing issue. Retesting in 2 to 3 days usually resolves the ambiguity.
True false positives from a correctly-used test are very rare. Most 'false positives' are actually chemical pregnancies.
A faint line on a pregnancy test that appears within the reading window (usually 3 to 5 minutes) is a positive result. It means hCG was detected, but the level is still low. This is common when testing early.
An evaporation line, on the other hand, is a mark that appears after the test dries — usually after 10 minutes or more. It is typically colorless or gray and does not have the pink or blue tint of a true positive line. To avoid confusion, always read your test within the specified time window and discard it after.
If you see a faint line and are unsure, retest in 48 hours. A true positive will be darker because hCG levels double rapidly in early pregnancy.
Small details in how and when you test can make a big difference.
Each brand has specific instructions for how long to dip the strip, how long to wait before reading, and the maximum reading window. A common mistake is reading the result too late (after 10 minutes), when evaporation lines can appear. Set a phone timer.
Your most concentrated urine of the day contains the highest hCG levels. This is especially important in very early pregnancy when hCG is barely above the detection threshold. If you must test at another time, avoid drinking large amounts of water for 2 to 3 hours beforehand.
If you are testing before your missed period, choose a test with a sensitivity of 10 to 15 mIU/mL (often labeled 'early result'). After your missed period, any standard test (20 to 25 mIU/mL) is sufficient. The sensitivity is listed on the package or insert.
If your first test is negative but your period does not arrive, wait 48 to 72 hours and test again. hCG doubles every 2 to 3 days, so a follow-up test is significantly more likely to detect a new pregnancy. A negative test one week after a missed period is highly reliable.
A blood test can provide definitive confirmation when home tests are unclear.
Home pregnancy tests are one of the most reliable over-the-counter diagnostic tools available. When used at the right time, they give you a clear, trustworthy answer. If your test is positive, it is almost certainly correct — even a faint line means hCG was detected.
Once confirmed, head to our positive test — now what? guide for your first action steps. Start prenatal vitamins, schedule your first prenatal visit, and check out what to expect during your first few weeks of pregnancy. If your test is negative but you are still trying, our trying to conceive guide has you covered.
This guide is for informational purposes only and is not a substitute for professional medical advice. Always consult your healthcare provider with any questions about your pregnancy.
