Sizing is a bugbear for most as you may be a size 14 in one brand and a size 18 in another! Yes, the difference can be that big. The thing to know is it's not you, it's the retailer/brand sizing ratio that is different. Jeans are notoriously difficult as you have to take into consideration the stretch in the denim which may mean you could go down a size! The first thing to do is to measure yourself especially if you're buying jeans online. Look at the retailer's size chart for the style and pinpoint where your measurements fit it. If you spread over two sizes then purchase both sizes and return the one that doesn't fit. Another tip I use a lot is to read other women's reviews which will guide you if the style is coming up large or smaller. Women are great at telling you how it is! For more insight on sizing read - Are we buying the right size jeans.