What is the thread size for my camera's lens?

I'm looking for a screw on, close up lens (like a filter) for my Nikon D80. My Nikon lens is 18-135mm.

I'm unsure of the thread size of my camera and this is required for the screw on lens. Can anyone help?

It should say on the front of the lens. Probably 67mm I would have thought.

Look on the lens barrel for the filter size.

ø 52 mm, 62 mm, 67 mm are typical Nikkor filter sizes

If all else fails, take your lens into a proper camera store and they can tell you

However with a little research, I was able to find that the filter size is 67mm. This should also be listed in the user guide that came with your lens

Too bad you have not been using a UV filter to protect your lenses front element from sticky fingers or blunt force trauma

I knew the tpi once for add on filters and other stuff in front of camera lenses.
But no matter. The 'size' of the threads has been standardized decades ago.
So all you need to know is the lens diameter to fit a filter or some other thing like what you are thinking of to screw on in front of your lens.

Go to an established camera store where the serious amateurs and pros even to to and ask away every question you have and, oh yeah, to but the stuff you need.

Somewhere on your lens there will be a Ø symbol followed by a couple of numbers, such as Ø55, the two numbers are your filter thread size in mm. That's the size of the close up filter you want, now you can get them off eBay and buy a set of four for the same price as a shop will charge for one.