In the Warmup/Mobility/Flexibility section of 5/3/1 Forever this isn’t mentioned anymore but I remember in the past reading to go for 40%, 50%, 60% as your warmup before starting on work sets.
Just do what it takes to get your body ready to perform. I’ve never used 40-50-60 with 5/3/1, and still found success with the program.
I usually use the 40/50/60 warm ups, and it still is prescribed in the Forever book.
That said, I also use other methods at times as well. Whatever gets you mentally and physically ready for your working sets.
I also still use the 40/50/60 warmup, though I don’t recall seeing it in Forever. It was in 5/3/1 2nd edition at least.
I do whatever I feel like, sometimes start with higher reps, then 5s, triples, singles, different increments. Sorry that’s quite vague but being primed and ready is more important than a strict %.
But if you want some clear guidelines Beyond lays out a specific plan with 10% increments.
Squats and deads just throw a 20kg plate on each side for increments, no need to overthink it.
I just warm up, a bit of jumping, arm swinging, leg swinging, skipping rope and general hopping about. Anything to get the body warm and loose, then bar, then plates each side then I’m into it. Just get warm and stay warm.
Roughly you can’t really go wrong with 10% jumps, but if you are using 2.5/5lb plates on warmups (maybe even 10lb for squat/DL) you are doing it wrong it just needs to be an estimate until the main sets. You shouldn’t have to do math to figure the warmups out and this is coming from someone who loves 531 because of the math/percentages part.
I typically just do the bar for as many sets as it takes until I’m sure everything is moving the way I want it to, then I’ll bump up in “standard” increments. Think 135, 185, 225, 275, etc. About 3-5 reps each, until I’m at my working weight. Figure the extra volume cant hurt.