For anybody else who found the sizing chart here unhelpful, I think I found a chart that provides actual measurements (or at least close estimates) of the Vidda Pro on Fjallraven Canada's site. I've read reviews where some say size up, others say size down, while others say they are true to size, I gave up trying to figure it out until I found this.
via: http://www.fjallravencanada.com/vidda-pro-trousers-regular.html#popguide