ARCT v1.1
Aspect Ratio Calculation Tool
by Ridwan Hughes

X = Y =      Source = PAL letterbox (4:3) PAL anamorphic (16:9) NTSC letterbox (4:3) NTSC anamorphic (16:9) PC normal (1:1) VCD (PAL) (4:3) VCD (NTSC) (4:3) SVCD (PAL) (4:3) SVCD (NTSC) (4:3) Output width = Aspect ratio = AviSynth border code: PAL letterbox (4:3) = PAL anamorphic (16:9) = NTSC letterbox (4:3) = NTSC anamorphic (16:9) = PC (1:1) =   HD (1080) (1:1) = HD (720) (1:1) = VCD (PAL) (4:3) = VCD (NTSC) (4:3) = SVCD (PAL) (4:3) = SVCD (NTSC) (4:3) =		This JavaScript utility is designed for me. I created it because I need to be able to calculate true aspect ratios of letterboxed PAL & NTSC video source and then convert those to letterbox or anamorphic, PAL or NTSC outputs for DVD creation. The final output aspect ratio hasn't been compromised by blindly sticking to 4:3, 16:9 & 2.35:1 aspect ratio rescaling, because 2.35:1 letterboxed laserdiscs aren't always a perfect 2.35:1 ratio. Aside from calculating anamorphic outputs of letterbox source, you can input 4:3 source and calculate anamorphic output with black side borders for if you're creating a fully anamorphic widescreen DVD and don't want to zoom+crop the source to fit. I added VCD/SVCD for those insisting on living in the dark ages of video ;)
The calculations for 4:3 & 16:9 aspect ratios are done using the ITU-R BT.601-4 standards so despite what's been said about this page, the results are accurate.