Pregnancy Test Calculator

Testing too early is the main reason for a false negative. Enter the first day of your last period and your cycle length, and we’ll show when a test is worth taking — and when the result is most reliable.

First day of your last periodAverage cycle length: 28 days

General estimates based on a regular cycle, not medical advice. Follow the instructions on your test, and confirm any result with your provider.

How it works

A pregnancy test detects hCG, a hormone that only appears after a fertilised egg implants — usually about a week after ovulation. Levels then rise quickly. A sensitive early test may show a faint line a few days before your period is due, but waiting until your period is late gives a far more dependable answer.

Frequently asked questions

When is the earliest I can test? +

Some early-detection tests can pick up hCG from about 10 days after ovulation, but a negative that early often just means it’s too soon. A faint positive is still a positive.

Why wait until my missed period? +

By the first day of a missed period, hCG is usually high enough for most tests to be reliable. Testing a few days later is more accurate still, especially if your ovulation date is uncertain.

When should I test with first-morning urine? +

Early in the morning your urine is most concentrated, so hCG is easier to detect. If you test early, first-morning urine gives the best chance of a clear result.