Are filter numbers universal?

[DocFrankenstein]

I keep hearing about filter #83... #81... or other ones.

Are these universal filters? Is there a chart of some kind?

[DaveG]

Filter numbering is pretty much universal and charts are available in many different publications. Getting a filter manufacturer's literature booklet might be the easiest and cheapest way to get this information.

But then there's Nikon. A UV filter in Nikon speak is an L37C (if it's multicoated) and a warming filter - an 81A - would be an A2. In a lot of ways the Nikon system makes more sense - at least in the colour filter side of things (A2 is amber for example) but it never caught on and is merely confusing.