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When to Take a Pregnancy Test Calculator

Find the earliest sensible day to test and the day results are reliable, from your ovulation date or last period.

Start from

Date

Cycle length (LMP mode)

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How it works

Reliable test = ovulation + 15 days (missed period + 1); early = ovulation + 10 days

hCG starts rising only after implantation (6–12 days past ovulation) and roughly doubles every two days, so sensitivity climbs fast: about 50% of pregnancies are detectable at 10 DPO, 85% at 12 DPO and over 99% the day after a missed period. First-morning urine concentrates the hormone.

Worked example

LMP 28 August with a 28-day cycle → ovulation 11 September → reliable test from 26 September.

Frequently asked questions

Why did I get a negative and then a positive?

You tested before hCG reached the test’s threshold. Wait 48 hours and retest.

Do irregular cycles change this?

Yes — use your ovulation date (from tests or temperature) rather than LMP if you can.

Related calculators

Implantation Date Calculator

Estimate when implantation happened or will happen from your ovulation, IUI or trigger date, your last period and cycle length, or an IVF embryo transfer (day 3, 5 or 6 embryo): the most likely day, the 8–10 day peak, the full 6–12 day window, when hCG can show up and when a home pregnancy test is reliable.

hCG Doubling Time Calculator

Work out your hCG doubling time and percent rise from two blood-test values and the hours between them.

Ovulation Calculator

Find your estimated ovulation day, fertile window, peak days and next period from your last period and cycle length — with a luteal-phase setting, irregular-cycle range and a table of your next six cycles.

Educational estimate only — your midwife or doctor will confirm dates and advice for your pregnancy.