Colludium Thanks for your data. We definitely want to get as close to Newton as possible.
However, neither my originally-proposed method nor the built-in calculation method is correct. We actually need to add (1/2)*g*t^2.
I made a mistake in my calculations. Due to the discrete/continuous difference Ashley mentioned, I mismatched position and velocity by one tick. When I fixed the error, Platform Minus gave a worse error than the built-in Platform behavior.
However, ADDING (1/2)*g*t^2 seemed to give a smaller error than the built-in calculations. I built a test program in Construct 2 that measures the unchanged, added, and subtracted jump heights.
Thanks to Aphrodite for the max height equation, the actual maximum height for a 650 jump strength and 1000 gravity should be 211.25 pixels.
The Platform behavior yields a 213.958 px jump height.
Subtracting (1/2)*g*t^2 gives a less-accurate jump height: 216.667 px.
But adding (1/2)*g*t^2 gives a jump height very close to the expected value: 211.285 px.
You can find the test .capx here.
To use it, go to debug and select the array. After you jump and land, the third array value will be your jump height. Press 0, 1, and 2 to toggle between the unchanged, subtracting, and adding calculation methods, respectively.