Pregnancy Test Timeline
Home pregnancy tests detect hCG, a hormone that starts rising after the fertilised egg implants — usually 6-12 days after ovulation. Testing too early is the most common cause of a false negative.
Enter your last period date and cycle length to see your estimated ovulation, the implantation window, the earliest a sensitive test could show a faint positive, and the day a test is most reliable — the day of your missed period. If a test is negative but your period does not arrive, retest in 48-72 hours since hCG roughly doubles every two days.
Medical disclaimer: This tool gives general estimates only and is not medical advice. Always confirm dates, results and any concerns with your doctor or midwife.
Formula
Ovulation ≈ LMP + (cycle length − 14) days Reliable test day ≈ LMP + cycle length
Example
LMP = 1 August 2026, cycle = 30 days. Ovulation ≈ 17 August. Implantation ≈ 23-29 August. Most reliable test = 31 August (missed period day).
How to Use
- 1. Select the first day of your last period.
- 2. Enter your average cycle length.
- 3. Click "Calculate".
- 4. Use the "most reliable" date for testing.
Frequently Asked Questions
When is the earliest I can test?
A sensitive test may show a faint positive ~8 days after ovulation, but false negatives are common that early.
When is a test most reliable?
From the day of your missed period — hCG is high enough for accurate detection.
What if the test is negative but no period?
Retest in 48-72 hours; hCG roughly doubles every 2 days.
Can irregular cycles affect this?
Yes — ovulation timing varies, so treat the dates as estimates.