It's not difficult to find good data on the distribution of births by day of pregnancy. But when you get closer to or past your due date, those numbers become less helpful for predicting your baby's birth. What you really need at that point is a simple way to compare your pregnancy to the other pregnancies that have lasted at least as long as yours. That's why I created the calculator below:I created this using Tableau 10.0 with the survey data from spacefem . This is a bit of a departure from the d3.js and leaflet.js driven visuals I've posted before; the main benefit to using Tableau is the incredibly short amount of time it takes to build something like this. I am curious about Tableau's usability with various internet browsers and on mobile devices, so don't hesitate to send me any problems you discover.