https://www.renderosity.com/freestuff/items/72218/the-universal-sizing-apparatus-hxwxd-inches

I use this to try to keep my scaling consistent. There is a metric version as well. Wall charts can be deceptive depending on the perspective and lens type of your poser camera.

BTW, I learned the hard way that if you use multiple (main, aux, posing, face) cameras in your scene for creating content, make sure they all match in focal length (35mm, 50mm, etc) otherwise you will have optical distortions between the different views.