What is Normal Kidney Size in mm?

Written by Hexahealth Care Team, last updated on 5 September 2023
What is Normal Kidney Size in mm?

The kidney is one of the essential organs of the human body. The organ's proper functioning is crucial for a person to live a healthy life. The human body has two kidneys, and their respective sizes indicate a person’s good health.

In this read, the focus will be to find out everything about the normal kidney size in mm, the factors determining the kidney size among men and women, and much more.

In the case of a healthy individual, the right kidney's normal size in mm is nearly similar to the left kidney's size. However, one must be aware that, in many cases, the dimensions can differ based on natural physiological changes or congenital abnormalities.

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Importance of Monitoring Kidney Size

A change in the size of the kidneys is one of the biggest indicators of a person suffering from an underlying health condition. The normal kidney size in mm is essential to ensure that all body's vital organs are healthy and performing their functions.

Even though there can be multiple factors causing changes in the size of the kidneys, an alteration in the normal size will surely bring many adverse effects to the body. The importance of monitoring kidneys sizes includes:

  1. Aids in the detection of kidney diseases
  2. Monitors the functions of the kidney
  3. Evaluates the effectiveness of the treatment 
  4. Allows the diagnosis of other health conditions
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The Normal Kidney Size in mm

Kidneys are an essential part of the body, and ensuring their right size is necessary to streamline the many essential body functions:

  1. The kidney size normal in mm among healthy individuals varies from the kidney lengths 79.56 ± 8.10 mm for the right kidney and 81.61 ± 8.32 mm for the left kidney. 
  2. The kidney widths are 35.03 ± 3.55 mm for the right kidney and 35.09 ± 3.57 mm for the left kidney. 
  3. The average weight of the kidney is around 79-223 gms for the right kidney and 74-235 gms for the left kidney. It constitutes 0.5 % of the total body weight. 

Factors that Affect the Size of the Kidney

The normal size of the kidney is analysed on average, as it differs from person to person. If there is a significant expansion or shrinkage in the average size, then it can be an indicator of a renal problem.

Several factors can be pivotal in affecting the normal kidney size in mm. Some of the most common factors include the following:

  1. Age: The size of the kidneys tends to decrease with an increase in age. This shrinkage is mostly caused due to the drop in the size and number of functional units within the kidney called the nephrons.
  2. Gender: Studies have found that gender plays a significant role in determining the size of the kidneys. Males have broader body builds and overall body compositions, as a result of which the normal kidney size of males in mm is larger compared to females.
  3. Body Size and Composition: People who are obese, tall, and have increased body mass will always have enlarged kidney sizes. Individuals who are short and petite will have small to average-sized kidneys.
  4. Medical Conditions: Several conditions can lead to either enlargement or shrinkage of the kidneys. Conditions such as polycystic kidney disease, renal tumours, etc., can cause enlargement. In contrast, conditions like renal atrophy and chronic kidney diseases can cause a reduction in the size of the kidneys.
  5. Anatomical Variations: There can be anatomical variations in the normal kidney size in mm. 
    1. Some individuals have conditions called solitary kidneys (a condition in which a person has only one kidney due to a birth defect, removal of one kidney, or kidney donation).
    2. Horseshoe kidneys (also known as renal fusion, this is a condition in which the kidneys are fused in the womb), etc., where the size is bound to differ.
  6. Surgical Procedures: A surgical procedure such as a kidney transplant or nephrectomy (surgical removal of a kidney) can play a vital role in determining the size of the kidneys.

Different Types of Kidney Sizes

Many medical conditions can cause shrinkage and enlargement of the kidneys. The increasing or decreasing size of the kidneys is an indicator of the changes taking place in the human body. The different kidney sizes are:

  1. Normal Kidney Size: Under this condition, a person has a normal right kidney size in mm and a normal left kidney size. This is an ideal situation which means that the kidneys are functioning properly.
  2. Enlarged Kidney Size: In this condition, one or both of the kidneys can be enlarged due to various medical conditions. These conditions include:
    1. Polycystic Kidney Disease: An inherited disorder in which clusters of cysts are formed in the kidney, causing enlargement and loss of functions over time. 
    2. Kidney tumours, or hydronephrosis: A condition in which the urine does not pass through the kidneys and remains inside the kidneys or the ureter.
    3. An enlarged kidney can also be the reason behind a lot of pain, discomfort, and urine-related problems.
  3. Small Kidney Size: Shrinkage of the kidneys or a significant reduction in the kidney size is not a good sign. The most common causes of this are:
    1. Congenital abnormalities
    2. Kidney damage
    3. Chronic kidney diseases

​​​​​A decrease in the size of the kidneys leads to improper functioning and kidney failure.

Symptoms Associated with a Change in the Kidney Size

The kidney and its proper function are essential for human life. Many factors can cause problems in this vital organ and significantly alter the kidney size normal in mm. Some of the prominent signs and symptoms of these changes are:

Symptoms of Enlarged Kidney Size: An enlargement in the normal kidney size in mm consist of the following signs:

  1. Discomfort or pain in the abdominal area or lower back
  2. Bloating or swelling in the abdomen
  3. Changes in urinary patterns (a difference in the colour and consistency of urine or experiencing an increased frequency or urgency for urination)
  4. Feeling fullness or pressure in the abdomen
  5. Weakness or fatigue
  6. Vomiting or nausea
  7. Fever in cases of infection
  8. High blood pressure 

Symptoms of Decreased Kidney Size: A shrinkage in the kidney size in mm consists of the following symptoms:

  1. Pain in your lower back and abdominal area
  2. High blood pressure
  3. Swelling or fluid retention in the legs, ankles, or face
  4. Symptoms of kidney dysfunction include difficulty breathing, loss of appetite, lack of concentration, change in skin colour and texture, etc.
  5. Nausea and vomiting 
  6. Fatigue and weakness
  7. High blood pressure

Measuring Kidney Size

The measurement of kidney size is an essential diagnostic tool to analyse the normal kidney size in mm and the changes that are taking place.

A delay in these tests can have serious repercussions, escalate problems, and cause permanent damage. Some effective ways of measuring kidney size include:

  1. Ultrasound: It is a non-invasive, safe, radiation-free method of measuring kidney size in mm. In this process, a radiologist or technician will use a transducer device to generate high-frequency sound waves that bounce off the kidneys and produce images of their shape and size.
  2. CT Scan:  Another effective test to measure the size of the kidneys, the CT scan uses ionizing radiation and is an invasive way to obtain a detailed image of the kidney and its surroundings.
  3. MRI:  A medical imaging technique that uses magnetic fields and computer-generated radio waves to obtain a clear image of the kidney. However, these methods can be expensive and time-consuming compared with the other tests.

Effective Ways to Ensure the Right Size of the Kidneys

Consuming a well-balanced diet and an active lifestyle is the key to maintaining the good health of your kidneys and overall body. Some easy and effective ways to ensure the well-being of the kidney are: 

  1. Stay Active: Regular physical exercises and activities are great for the overall well-being and the health of the kidneys. 30 mins of moderate-intensity exercise, such as brisk walking, cycling, running, etc., are great for eliminating chronic kidney problems.
  2. Manage Blood Sugar: People with diabetes or high blood sugar are at increased risk of developing kidney-related problems. When the body constantly struggles to absorb the extra glucose, it becomes difficult for the kidneys to filter blood. This continuous exertion implies life-threatening challenges. Therefore, one must strictly check their sugar intake and practice blood sugar management.
  3. Blood Pressure Monitoring: High blood pressure can be another reason causing kidney damage. Anyone facing high blood pressure must immediately consult their doctor and begin medication.
  4. Balanced Diet: One needs to understand that the kidney is responsible for flushing out all the wastes from the body. The more toxins one eats in the form of junk and unhealthy food, the tougher it becomes for the kidney to perform its function effectively. A well-balanced and healthy diet does wonders for not only your body but also your kidneys.
  5. Stay Hydrated: Proper hydration is a must to ensure good health of the kidneys. Plenty of fluids ensure that all toxins are easily flushed out from the body, refusing the workload on the kidneys. One must significantly increase the number of fluids based on age, climate, and body conditions.
  6. Management of Chronic Conditions: Many health conditions can further escalate the improper functioning of the kidneys. One must follow timely and proper medications and share feedback with the healthcare provider.
  7. Avoid Smoking and Alcohol Consumption: Smoking damages the blood body vessels, which can significantly impact the proper functioning of the kidneys. Excessive alcohol consumption can also cause adverse effects. Therefore, one needs to check their smoking and drinking habits.
  8. Safe Sex: Sexually transmitted infections, when left untreated, can become one of the potent causes of kidney damage. Practice safe sex by using condoms, and immediately seek the advice of an expert if you feel you are suffering from STIs.

Treatment for Abnormal Kidney Size

The right size and the proper functioning of the kidney are essential. Some standard procedures that can help in treating this problem are:

  1. Regular Blood Checks: Undergoing regular blood tests can help you keep track of kidney function as blood tests measure the electrolyte levels in your body. If the electrolyte levels are abnormal, then it indicates kidney disorder.  
  2. Monitoring Blood Pressure: Regular monitoring of blood pressure should be done by hypertensive patients, as high blood pressure can damage the blood vessels of the kidney and eventually damage the kidneys.
  3. Medication: Medicines are the first line of treatment for any disease. Medications such as diuretics can be prescribed by doctors in case a kidney disorder has been diagnosed. Diuretics help to flush out excess fluids from the body.
  4. Dialysis: It is a medical procedure which is performed to remove the waste products from the body when the kidney has failed to perform its function properly.
  5. Kidney Transplant: Kidney transplant is a procedure performed to remove a diseased kidney with a normal functioning kidney in patients with end-kidney disease stage. 

When to Seek Medical Help?

A change in the size of the kidney is a common indicator of severe problems in this organ. Whether there is a change in the normal right kidney size in mm or the left one, it is crucial for a person not to take this problem lightly and seek the help of a healthcare provider at the earliest. If one can slightly feel the differences in their body, they must go to a doctor.

The sooner this problem can be addressed and extracted, the better it is. The complications and risks will surely rise if kidney problems are detected in progressed stages. If you are experiencing any of the above-mentioned symptoms, consult your doctor. They will check your blood pressure and prescribe blood tests to analyse your condition.


Knowing the kidney's normal size in mm is essential to lead a healthy and normal life. If a person feels changes in their urinary patterns, has constant swelling, feels fatigued, has nausea, etc., these symptoms must never be taken lightly as they can indicate a serious underlying health condition. The wise and smart thing to do is call your doctor and share your health conditions.

HexaHealth is one of the leading and most reliable platforms for health. HexaHealth allows individuals to smoothen and streamline processes related to their health journey. From helping you find the best hospitals to specialists and expert healthcare providers, we are here to do everything for you. Our experts also assist you in clearing your health policies, getting discounts, using coupons, and much more. To find out more, consult us at HexaHealth TODAY!

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Frequently Asked Questions

What is the normal kidney size in mm?

A. Many factors determine the size of the kidneys. The normal kidney size in mm varies from the kidney lengths 79.56 ± 8.10 mm for the right kidney and 81.61 ± 8.32 mm for the left kidney. The kidney widths are 35.03 ± 3.55 mm for the right kidney and 35.09 ± 3.57 mm for the left kidney

What is the right kidney normal size in mm?

Reports suggest the right kidney size in mm is slightly more than the left. The approximate right kidney's normal size in mm is 79.56 ± 8.10 mm.

What is the average size of the left and right kidney in millimetres?

The size of the kidneys and the changes in the size are prominent indicators of problems and health conditions related to the kidney. A person does not need to worry if there are no issues with their normal size.

The normal right kidney size in mm varies in length, 79.56 ± 8.10 mm for the right kidney and 81.61 ± 8.32 mm for the left kidney. The kidney widths are 35.03 ± 3.55 mm for the right kidney and 35.09 ± 3.57 mm for the left kidney.

Which kidney is smaller right or left?

Although there is no significant difference between the left and the right kidney size, the left kidney is slightly larger than the right kidney. It is also positioned slightly higher and closer to the heart than the right kidney.

Is there a difference in the normal size of the left and right kidney in millimetres?

Yes! A person who is healthy and free from kidney-related problems will have a slight difference in the normal size of the left and right kidney in millimetres.

Why is the right kidney small?

The right kidney can be approximately 1 cm smaller than the left. Generally, the reason behind this is dysplasia (developmental defect in the kidney while the baby is in the mother's womb), due to pyelonephritis (infection of the kidney which commonly occurs in early childhood), or due to narrowing of kidney arteries supplying blood to the kidney.

What factors affect the size of the kidney in millimetres?

Many factors can affect the right kidney's normal size in mm. Some of the most prominent factors are:

  1. Age 
  2. Height 
  3. Weight 
  4. Surgical procedures
  5. Anatomical variations
  6. Medical conditions 

Can the size of the kidney change over time?

Yes! There is bound to be a change in the kidney size in mm with a person's age. As a person ages, there is a shrink in the number and size of the functional units within the kidney. As a result, the size of the kidneys decreases with an increase in age.

How is the size of the kidney measured in millimetres?

To obtain a clear understanding of the size of the kidney, a procedure called ultrasound or CT scan is done. These tests can analyse the kidney's size and detect other kidney-related problems.

What is considered an abnormal kidney size in millimetres?

There is no fixed abnormal kidney size range. However, kidney sizes that are getting enlarged or shrinking are considered abnormal and can adversely affect a person's overall health.

Does age affect the size of the kidney in millimetres?

Yes, age plays a vital role in affecting the size of the kidney in millimetres. As the person's age increases, there has been known to be a reduction in the normal kidney size in mm.

What are the implications of having a kidney larger or smaller than the normal size in millimetres?

The implications of having a kidney larger or smaller than the normal size in millimetres are strongly indicated towards underlying health conditions. In such situations, a person should consult their healthcare provider as early as possible.


All the articles on HexaHealth are supported by verified medically-recognized sources such as; peer-reviewed academic research papers, research institutions, and medical journals. Our medical reviewers also check references of the articles to prioritize accuracy and relevance. Refer to our detailed editorial policy for more information.

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  2. Vassalotti JA, Stevens LA, Levey AS. Testing for chronic kidney disease: a position statement from the National Kidney Foundation. American journal of kidney diseases. 2007 Aug 1;50(2):169-80.link
  3. Porter RS, Kaplan J, editors. The Merck manual go-to home guide for symptoms. Simon and Schuster; 2013 Oct 29.link
  4. Abecassis M, Bartlett ST, Collins AJ, Davis CL, Delmonico FL, Friedewald JJ, Hays R, Howard A, Jones E, Leichtman AB, Merion RM. Kidney transplantation as primary therapy for end-stage renal disease: a National Kidney Foundation/Kidney Disease Outcomes Quality Initiative (NKF/KDOQI™) conference. Clilink
  5. National Heart, Lung, Blood Institute, National Institute of Diabetes, Digestive, Kidney Diseases (US). Clinical guidelines on the identification, evaluation, and treatment of overweight and obesity in adults: the evidence report. National Heart, Lung, and Blood Institute; 1998.link

Updated on : 5 September 2023


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HexaHealth Care Team

HexaHealth Care Team brings you medical content covering many important conditions, procedures falling under different medical specialities. The content published is thoroughly reviewed by our panel of qualified doctors for its accuracy and relevance.

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