PAL to NTSC, what is the correct 'Stretch' factor?

[ForSerious]

I have the audio and subtitles from a PAL DVD, and the video from a higher quality NTSC source. I figured out how much to slow the audio down to get it right.
I'm using MKVToolNix to join the subtitles from the PAL DVD into the final mkv file.
For the stretch by box on the subtitle, I tried a lot of numbers and settled on 1.034. That seems to be okay for up to 8 minutes.
Does someone who knows what kind of math needs to be done here, or have done this before, have a better answer? (I got tired of searching.)

[manono]

It seems to me you'd slow the subs down by the same amount you did the audio. That's assuming the audio stays in synch all the way through after having been slowed down.
However, 25/23.976=1.04271.

[ProWo]

23.976/25=0.95904 for me.

[Sharc]

There might be an offset as well which needs to be added (subtracted) for sync alignment.

[jagabo]

And you may have different cuts of the movie (scenes deleted or added) which you'll have to account for.

Regarding the different numbers given by manono and ProWo: dividing by 1.04271 is the same as multiplying by 0.94904. Ie, 1/1.04271 ~= 0.95904.

[ForSerious]

Oh right, I do have different cuts. I very forgot to make the same cut on the DVD. I'll report back once I get that worked out.

[ForSerious]

Thank you everyone! 1.04271 is the correct number.

The hardest part was figuring out where to cut the DVD to match the NTSC source where I cut it. I only checked my original number near the end of the clip, so it's probably out of sync at the start.

So, I probably did find the right answer in all my searching. I just forgot about the fact that I'm cutting the start and end off.