Which size dslr filter do I need?

I've got the Nikon D5100 with the 18-55 kit lense. For Christmas I'm hoping to get some filters, what size do I need to get to fit?

Look inside your lens cap for the number followed by a mm, that number is the filter size.

The 18-55mm kit lens has a 52mm filter thread I believe.

You could also look at square filters you will still need to get the adapter ring see answers above but square might be a cheaper option for you

Deep blue is right 52mm filter for 18-55mm kit lens… Thank you

52mm for a Nikon kit lens. Remember, it's the lens filter diameter that matters, not the model of DSLR.

Some good filters to begin with:

Circular Polarizer (A must for outdoor photography. Less reflections, richer colors, bluer skies)
Cross-screen star filter (Adds rays to pinpoints of light, a fun filter)
Close-up filters set (Turn your kit lens into a macro lens)