Kidney Stone Size And Passage. The probability of a stone passing through urine decreases with the increase in the size of the stone. The trouble is the average human ureter is roughly 3 4mm in exterior diameter interior diameter is about 2 3mm and about 10 12 inches long.
Once the kidney stone leaves the physical kidney itself it will now be traveling down the path of your ureter. Stones that are 4 6 mm are more likely to require some sort of treatment. They take an average of 31 days to pass.
Kidney stones of less than 5mm are considered to be small.
There is also an increase in the time to pass to roughly 60 days. Stones smaller than 4 millimeters mm pass on their own 80 percent of the time. Kidney stones that are 6 9mm in diameter are considered to be large with this size kidney stone the likelihood of passing it unassisted drops significantly to about 20. Kidney stones of less than 5mm are considered to be small.