Early pregnancy calculators
Early pregnancy calculators — 3 tools, each showing the formula it uses, the source that published it, and the date that source was last checked.
Conception date calculator
A conception date calculator subtracts 266 days from an estimated due date, or adds 14 days to the first day of a last period, following the convention ACOG publishes. It returns a conception window rather than a single day, because sperm survive for several days and ovulation timing varies between cycles.
Implantation calculator
An implantation calculator dates the window in which a pregnancy implants, from your estimated ovulation date. Wilcox and colleagues measured this directly in 1999: implantation happened 6 to 12 days after ovulation, and 84 percent of it on days 8, 9 or 10. This page carries no ads.
hCG doubling time calculator
This works out the doubling time between two hCG results and the percentage change between them, using the interval you enter. It shows the arithmetic and the slowest rise Barnhart and colleagues recorded in 2004 for a viable intrauterine pregnancy. It does not interpret your result. This page carries no ads.
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