I've been fooled before with sizing guides. I used to be a size 32 and one time I bought a pair of snowboard pants that said fits waist size 30-32 so I figured I'd get a nice snug fit...nope. The damn thing must have been 2-3 inches bigger because I couldn't keep it up even after I pulled the velcro waist tabs to max. Sometimes it even depends on the model of pants even if they are the same cut, like I bought 2 Burton pants that both were Sig Fit but were different models. One fit perfectly, the other one had me sucking in my gut even though they were both Small.
Find a brand that fits you and stick with it. I once bought some 686 pants in size Small and they were the absolutely fucking perfect freaking fit. Perfect waist, and perfect inseam. I won't buy any other pair of pants except 686 and I know that no matter what online store I buy them from I can safely purchase a size Small and have it fit. Same with boots, I bought a pair of Thirty Two and they fit perfectly with no adjustments needed. Will continue buying from them for my boots.
It saves on hassle/returns when you purchase from a brand that you know will work for you. If you must, purchase from places like Dogfunk where you can order like 3 different sizes of jacket if you want then return the 2 that didn't fit and keep the one that does. Brick and Mortar stores just can't carry the metric shit ton of gear that a place like Dogfunk can which just has giant warehouses filled to the brim.