Resolution Calculation

before we start never ever upscale for example your source is just 480p and you want it 720p that is wrong thinking, you will only make the video blurry 

ok back to the main guide if your wandering how to get properly the resize resolution of a source video here is the simple way

for example you got a source of 1280x960
then lets say you want to downsize to 576p:
1280 = 960
x = 576
then cross multiply:
x960 = 737280
x = 768
so its:
768x576
to check:
1280/960 = 1.333
768/576 = 1.333
1.333 = 1.333
so your 576p resolution is 768x576

for example you got a source of 1280x720
then lets say you want to downsize to 400p
1280 = 720
x = 400
then cross multiply:
x720 = 512000
x = 711
so its:
711x400
to check:
1280/720 = 1.77
711x400 = 1.77
1.77 = 1.77
so your 400p resolution is 711x400

for example you got a source of 1280x720
then lets say you want to downsize to 480p
1280 = 720
x = 480
then cross multiply:
x720 = 614400
x = 853
so its:
853x480
to check:
1280/720 = 1.77
853/480 = 1.77
1.77 = 1.77
so your 480p resolution is 853x480

thats it you got it now