Optimize Pregnancy Testing

Provide your cycle or ovulation data to estimate when hCG levels reach detectable thresholds for urine and blood tests.

Last period start (optional if ovulation known)

Average cycle length

Luteal phase length

Typically 12–14 days. Adjust if you track basal body temperature or progesterone.

Ovulation date (optional)

Overrides calculated ovulation if provided.

Test sensitivity (mIU/mL)

Planned test date (optional)

Receive guidance on whether your planned test date is optimal.

Provide either a period start date or ovulation date.

How to Use This Calculator

Enter your cycle or ovulation data

Use the last period start if you don’t track ovulation; otherwise supply a confirmed ovulation date.

Choose test sensitivity

Check packaging for mIU/mL thresholds to understand how early your test may detect pregnancy.

Plan testing and follow-up

If initial results are negative before your expected period, retest after the missed period or obtain a serum hCG.

Formula

Ovulation date (if unknown) = Period start + (Cycle length − Luteal length)

Earliest serum detection ≈ Ovulation + 8 days (hCG ≥5 mIU/mL)

Earliest urine detection ≈ Ovulation + 10 days (hCG ≥10–20 mIU/mL)

Best accuracy = Ovulation + Luteal length (first missed period)

Full Description

Human chorionic gonadotropin (hCG) becomes detectable after implantation, typically 6–10 days post ovulation. Serum hCG assays detect lower levels earlier than urine tests. Home pregnancy tests vary in sensitivity; ultra-sensitive tests provide earlier positives but still risk false negatives before the missed period. Testing too early may miss late implantations. If menstruation is delayed and tests remain negative, seek medical evaluation to rule out late ovulation, biochemical pregnancy, or other causes.

Frequently Asked Questions

Can dehydration affect urine tests?

Yes. Diluted urine may lower hCG concentration. Use first-morning urine for early testing.

What if I get a faint line?

Any positive line suggests hCG presence. Repeat testing in 48 hours or obtain a quantitative serum hCG for confirmation.

Can fertility medications interfere?

Yes. hCG-trigger injections can cause false positives for up to 10 days. Time your test after the trigger has cleared.

What if tests stay negative but my period is late?

Consult your clinician. Potential causes include anovulatory cycles, delayed ovulation, or hormonal imbalances.