How Big are Kidney Stones?

Aastha Kapoor   by Aastha Kapoor, MS, Biotechnology    Last updated on December 22, 2019,

kidney stone size chart


Kidney stones (Renal Calculi)

Kidney stones are hard substances formed within the urinary system. They are also referred as Nephrolithasis. Stones are formed due to decrease in urine volume or accumulation of unwanted toxic substances. Dehydration is the major cause of occurrence of kidney stones. Renal Calculi have a highly distant physical appearance.

Size of kidney stones

Kidney stones are of variable sizes. They range from small sized crystals (small kidney stones) to large sized stones (large kidney stones) such as the size of a golf ball. Variations in sizes of kidney stones affect the following things:

Treatment of kidney stones

The size of kidney stones affect the treatment method required for their removal. Small-sized stones can easily pass through the kidney without any medical assistance but large-sized stones require medical intervention. Certain tests are conducted which help in determining the size of kidney stones, such as KUB, an Ultrasound or an IVP. They help in analyzing which treatment should be effective for the removal of your kidney stones.

Time needed for passing kidney stones

The size of kidney stones determine the time needed for their removal from the kidneys. Smaller the size of a stone, the faster it can pass through the urinary tract. For example, a 2mm stones may pass through the kidneys in about 12 days but stones of size 4mm can take about 30 days to pass out.

Read about passing of the kidney stones in urine.

Composition of kidney stones

The size of the stones can also indicate the compounds they are made of. Kidney stones can have a variety of compositions such as calcium, uric acid, struvite and cystine stones. They are formed by deposition of toxic compounds in the kidneys. An increased deposition of toxic compounds may result in the formation of large-sized kidney stones, which can cause blockage in the urine path.

Here is a chart that indicates the types of kidney stones and their shapes/sizes.

Type of stones Incidence rate Shape Cause Clinical risk factors
Calcium oxalate About 80% Envelop Increased calcium and oxalate in urine Higher chances in middle age men than women
Calcium phosphate < 5% Amorphous Increased calcium and pH Hyperparathyroidism and renal tubular acidosis
Uric acid About 10% Diamond or rhomboid Increased uric acid and pH of urine Gout and diabetes mellitus
Struvite About 10% Coffin-lid Increased  pH of urine Neurogenic bladder and other anatomic abnormality
Cystine < 1% Hexagonal Rare genetic disorder: increased cystine in urine  


Can small kidney stones pass naturally?

Kidney stones of less than 5mm are considered to be small. Small kidney stones can easily pass through the urinary tract without any medical assistance. 4mm size stones have 80% chances to pass through the kidneys in about a month, but 5mm size stones have 60% chances of passage in about 45 days.

To pass small-sized kidney stones naturally in urine, certain home remedies can be helpful such as increased fluid intake, increased water, lemon and citrus juice consumption and low salt, calcium and protein diet. High water concentration does not allow growth of kidney stones and they can slowly pass along with the urine.

If you experience any pain in the lower abdomen during passing of the kidney stones, you can take an analgesic such as ibuprofen or any other painkiller as suggested by the doctor. Painkillers help in relieving pain and also speed up the process of passing the stone. Read about relieving kidney pain.

How big are kidney stones? How can they be removed?

Have you ever wondered how big are kidney stones? Stones of > 5mm size are considered as large kidney stones.

Large-sized stones cannot pass through the kidneys without any medical intervention. If they are left to pass on their own, they may take longer time, about a year or more than that and there is a risk of complications. Large sized stones may get struck in the urinary tract and cause extreme pain and bleeding during urination.

The methods involved in the removal of large-sized kidney stones are as follows:

Extracorporeal shock wave lithotripsy (ESWL)

Extracorporeal shock wave lithotripsy is the most common method for the treatment of stones which cannot pass through the urine. This involves administration of ultrasound (high-frequency sound waves), which results in breakdown of the stones into smaller pieces so they can easily pass along with urine.


Ureteroscopy is also known as retrograde intrarenal surgery (RIS). When large-sized kidney stones get struck in the ureter, ureteroscopy may be carried out.

This involves inserting a ureterscope (long, thin telescope) through urethra into the bladder, to the site where the stone got struck in the ureter. Your surgeon may remove the stone using another instrument or by laser energy, which breaks the stone into smaller pieces and allow it to pass naturally through the kidneys.

Percutaneous nephrolithotomy (PCNL)

Percutaneous nephrolithotomy is suitable for removal of extremely large-sized stones and for obese people. This involves passing a nephroscope (thin telescopic instrument) into the kidneys through a small incision in the back. The stone is then either pulled out or broken into small pieces by pneumatic energy.

Open Surgery for kidney stones removal

Open surgery is carried out in rare cases, either when you have a huge stone or abnormal anatomy. This involves an incision to be made in the back to provide access to your ureter or kidneys from where the stone can be easily removed.

What is a kidney stone size chart?

Kidney stones vary in sizes. Therefore, as discussed above, the composition, their treatment and removal, time they take in passing through the urine, and their other characteristics may also vary based on their sizes. A kidney stone size chart is an easy way to tabulate and illustrate the important pieces of information about one or more of these factors associated with varying sizes of kidney stones.

A kidney stone size chart may show a correlation between possible treatment options and various sizes of the kidney stone. Another type of a kidney stone size chart may show correlation between kidney stone sizes and their compositions and so on.

Kidney stone size chart and its features

This is a simple kidney stone size chart that that provides important information about the chances of passing stones naturally, time taken, and treatment required for various sizes of the kidney stones. More types of kidney stone charts can be possible to show different types of information pieces about kidney stones and their sizes.

Size of kidney stones Chances of passing naturally Time required to pass naturally Treatment
Less than 2mm About 80% 8 days (average) Home remedies
2-4 mm About 80% 12 days (average) Home remedies
4mm About 80% 31 days (average) Home remedies
4-7mm About 60% 45 days (average) Home remedies and painkiller
Larger than 7mm About 20% 12 months (average) Ureteroscopy
1-2cm Cannot pass   Lithotripsy
Larger than 2cm Cannot pass   Percutaneous nephrolithotomy