Understanding your fertile window can help with family planning, whether you're trying to conceive or avoid pregnancy naturally. Enter your cycle details to estimate your next ovulation date.
Understanding your fertile window can help with family planning, whether you're trying to conceive or avoid pregnancy naturally. Enter your cycle details to estimate your next ovulation date. This calculator draws on peer-reviewed, industry-standard formulas used by fitness professionals, dietitians and clinicians worldwide, translated into a fast, easy-to-use browser tool.
Tracking metrics like this over time — rather than relying on a single reading — gives you a much clearer picture of trends in your health and fitness journey. Use this tool regularly alongside our other calculators for a fuller picture of your overall wellbeing.
Ovulation typically occurs 14 days before your next period begins, so it's calculated as (cycle length − 14) days after your last period started.
The fertile window generally spans about 6 days — the 5 days before ovulation plus ovulation day itself — since sperm can survive several days in the reproductive tract.
This calculator is most accurate for regular cycles. If your cycles vary significantly, consider tracking basal body temperature or using ovulation predictor kits for more precision.