Do kidney stones sink or float?

Beta, they are made of solid calcium and salts, so they will always sink down. If you are expecting to pass one, the doctor might ask you to strain your urine using a clean cloth so you can collect it.

I was so worried about this when I thought I passed mine! They definitely sink because they are heavy like tiny rocks. If you are trying to catch it to show the doctor, definitely use a strainer because it won't float at all.

Since they are dense mineral crystalline structures, kidney stones will sink immediately. If you are tracking your symptoms to report to your doctor, try using a urine strainer so you don't lose the sample down the drain.

They sink because of their high density. When I was trying to pass my 4mm stone, I did a lot of walking as my doctor suggested, and kept checking the strainer. Straining is the only way to catch it since it goes straight to the bottom.

They are literally rocks, my friend, so they will sink like a stone in water! Don't expect them to bob around like ice cubes. If you want to keep it as a painful souvenir, you'll have to catch it before it hits the bowl.