How big is a kidney stone?

The size of a kidney stone ranges between a crystal of sugar to a ping pong ball, according to WebMD. Most people do not notice kidney stones until they begin to cause damage.

Kidney stones form when salts and minerals in the urine stick together and crystallize. Many are too small to notice, and only cause pain when they enter the ureters that lead into the bladder. When this happens, the pain becomes severe, alerting the patient to their presence.

People with kidney stones may experience:

• Blood in their urine (hematuria)
• The need to urinate more often
• Nausea and vomiting
• Severe pain around the back, groin and sides