The only “calculator” That will work accurately involves a jack, scales, trig, and a tape measure. You need to know your placement of the center of gravity front to rear, and top to bottom.
Hoping my answer doesn’t come of as sarcastic, but finding the CG is the only way of accurately predict the antisquat line. No online calculator will help without that piece of info.
Also fact.
However, a person can make (or plan to make) a bar change, plot the difference in locations in reference to the imaginary line drawn according to cam height, front axle C/L, etc. and have a reasonable expectation the the car will want to squat or rise, less or more, as a result of that change. If it doesn't, see my sig line. Testing will tell you if you were right. Good shocks will be useful (needed) as you get further away from 100% A/S, wherever that happens to be.
Shocks, weight location, specific bar geometrys, etc. are what really make the difference. The A/S number is more of a reference for where you've been and where you're going and what you should expect to see. Not an exact location without doing all of the calculations. Moving the IC lower in reference to your A/S line on your 4 link map, will make the car want to squat more, or rise less, after the hit. Not because of where that imaginary line and the IC are. But because you have lowered the angle of the bottom bar and/or changed the leverage of the top bar.