Estimate per-cycle conception probability and cumulative chances over 3, 6, and 12 months based on maternal age, with clinical guidance on when to seek help.
Share this calculator
Also in Fertility & Pregnancy
Health — Fertility
Female fertility declines with age, primarily due to a reduction in both egg quantity and quality as the ovarian reserve diminishes over time. This calculator provides evidence-based per-cycle conception probability estimates and cumulative probabilities over 3, 6, and 12 months, based on published epidemiological data from studies including Dunson et al. (2002) and ASRM guidelines.
Under ideal circumstances, a healthy couple under 30 has approximately a 20–25% chance of conception per menstrual cycle. This probability declines gradually through the thirties and more rapidly after age 37.
The figures used in this calculator represent typical population averages. Individual fertility depends on many additional factors including male factor, uterine health, hormonal balance, and general health status.
Because pregnancy attempts are repeated each cycle, cumulative probability rises substantially over months of trying. The formula P(at least one conception in n cycles) = 1 − (1 − p)ⁿ gives the combined probability, assuming each cycle is an independent event.
At age 30 with a 20% per-cycle rate, the cumulative probability after 12 cycles is approximately 93%. At age 40 with a 10% per-cycle rate, 12 cycles gives approximately 72%.
P(n cycles) = 1 − (1 − p)ⁿ
Cumulative conception probability over n independent cycles
Most guidelines recommend evaluation after 12 months of regular unprotected intercourse for women under 35, and after 6 months for women aged 35 or older. Women over 40 should generally seek advice promptly.
Frequently asked questions
The per-cycle probabilities reflect data from couples where both partners are assumed to be fertile. Male factor infertility (present in approximately 40–50% of infertility cases) is not factored into these estimates.
Yes. IVF success rates are reported separately by clinic and age group. They are not directly comparable to the natural per-cycle probabilities shown here. Consult a fertility specialist for IVF-specific success estimates.
Related
These related calculators come from the same leaf category, nearby sibling categories, or the same top-level topic.
Estimate fertile days, ovulation timing, peak fertility dates, and the next period from your cycle pattern.
Estimate ovulation, fertile days, and the next period date from your cycle length and luteal phase settings.
Estimate conception date and fertile window from your last menstrual period and cycle length, or work backwards from a known due date.
Adjust your basal body temperature reading for non-standard wake times and see whether your temperature falls in the pre- or post-ovulation range.
