What lens cap size will fit nikon 18-55mm lens of nikon d5100?

What lens cap size will fit nikon 18-55mm lens of nikon d5100?

Any lens cap for 52mm filter threads will fit.

The size of filter threads is written on the lens. Just search for the 52mm figure on your lens to see where Nikon usually puts it.

If you are looking to protect the lens of your camera you would be better off getting a 52mm UV filter. All professional photographer us this filter on their lenses.
1. The filter protects the lens.
2. The front surface of the filter is easily cleaned.
3.buying a filter usually involves about a $15.00 investment.
If you rub the lens coating off or scratch your lens, you are looking at a very expensive repair and months waiting for the repair to be done. With that knowledge it is just good sense to use a filter to protect your valuable lenses.

Also you are ready for action by not having to remove the lens cap, and then where do you put the cap while you are not using it?