IVF Success Calculator — evidence-based tool to check your ivf success. Includes formula, tips, and interpretation guide.
Ovulation day = LMP date + (cycle length − 14 days)
The luteal phase (ovulation to next period) is relatively constant at 14 days across most people, while the follicular phase (period to ovulation) varies. Subtracting 14 from the cycle length gives the length of the follicular phase — the number of days after LMP that ovulation occurs. The fertile window is then: ovulation day − 5 days to ovulation day. The next period is estimated as LMP + cycle length.
Worked example: LMP = 1 April, cycle length = 30 days. Ovulation = 1 April + (30 − 14) = 17 April. Fertile window = 12 April to 17 April. Next period = 1 May. Sperm viability window makes 12–17 April the highest-probability conception window.