We looked at this a while ago, but they’ve recently updated it and made the reference even better!
Click Here to Get Your GW Beveled Bases For Less! Most of the time, it’s nearly impossible to find the exact “official” base size for Warhammer 40k models! You have to use other online resources like here or GW’s own website if the items are still listed or even updated. This is a living article: I update it as new releases hit the shelves. Maybe some fellow hobbyists might find this helpful as well. Thus I’ve had a feeling that some king of basing guide could be useful. While it wasn’t a big problem up to a while ago, many recent GW models use unusual (and often unique) bases. When it comes to scratch-building, kit-bashing and deep conversions it is often necessary to know a size of a base the finished model is supposed to be put on.