Urine Specific Gravity: What It Tells You About Hydration and Kidney Health

By Dr. Diana Rangaves, PharmD

Your urinalysis results are in. You notice a number next to urine specific gravity, but you don’t even know what it actually means. Is it too high, too low, or right where it should be? And more importantly, what could it be telling you about your hydration or kidney health?

It’s normal to feel unsure when faced with lab terms like this. The good news is, urine specific gravity is one of the simplest markers to understand once you break it down.

This article will explain Urine Specific Gravity: What It Tells You About Hydration and Kidney Health, and why it’s a simple but valuable test.

What Is Urine Specific Gravity?

Urine specific gravity is a simple test that measures how concentrated or diluted your urine is. Normally, urine is a combination of water and dissolved substances such as salts, electrolytes, and waste products. What urine specific gravity tells us is the ratio of the density of your urine compared to the density of pure water. [1] This makes it a quick way to see how well your kidneys balance water and remove waste products from your urine.

Healthcare providers often use it as an indicator of how well your kidneys are balancing fluid levels in your body. [1] A urine sample that’s very diluted may suggest you’re overhydrated, while one that’s highly concentrated can point to dehydration or, in some cases, an underlying kidney issue.

What Is the Typical Urine Specific Gravity?

For most healthy adults, urine specific gravity (USG) typically falls between 1.005 and 1.030. [2] Pure water has a value of 1.000, so anything above that reflects the presence of dissolved substances like salts and waste products.

• Less than 1.0101: Very diluted urine, often after drinking large amounts of fluid. [1]

• Around 1.005 –1.030: Considered a normal range. [2]

• More than 1.030: More concentrated urine, which may happen with dehydration, vigorous exercise, or less fluid intake. [1]

It’s important to remember that a single reading outside the “typical” range doesn’t always signal a problem. Temporary factors like exercise, diet, or even certain medications can influence the result. [1]

What Does Urine Specific Gravity Reveal About Hydration?

One of the most practical ways to check hydration is through urine specific gravity. Because it reflects how concentrated your urine is, it can give a quick picture of whether your body has too little, too much, or just the right amount of fluid.

Here’s how different readings often line up with hydration levels:

• Lower USG (< 1.0101): Very diluted urine, often after drinking a lot of fluids.

• Normal USG (around 1.005 to 1.030): Typically signals balanced hydration.

• Higher USG (> 1.030): More concentrated urine, often linked to dehydration or fluid loss from sweating, diarrhea, or vomiting.

So if you’ve ever wondered whether you’re drinking enough water, your USG result can serve as a simple clue.

Still, it’s not a perfect hydration meter. USG can be influenced by other factors like diet, medications, or kidney health, so results are best interpreted in context. [1]

What Does Urine Specific Gravity Reveal About the Kidney?

Another important aspect of urine specific gravity is what it can reveal about your kidney health. The kidneys are responsible for filtering waste and balancing fluid levels in your body, and USG reflects how well they’re doing that job. [3]

A healthy kidney can adjust urine concentration depending on your hydration needs, making it more concentrated when you’re dehydrated and more diluted when you’re well-hydrated. [3] But if your USG values stay unusually high or low, it may point to issues with kidney function or related conditions.

Dilute urine can sometimes be linked to problems such as diabetes insipidus, chronic kidney disease, kidney infections, or kidney failure. [1] On the other hand, concentrated urine may be caused by dehydration, vomiting, diarrhea, reduced blood flow to the kidneys, or hormonal issues like syndrome of inappropriate antidiuretic hormone secretion (SIADH) or Addison’s disease. [1]

That’s why USG is often used as a simple but valuable clue when assessing kidney health, especially when interpreted alongside other tests and clinical findings.

How Is Urine Specific Gravity Performed?

Urine specific gravity is usually checked as part of a routine urinalysis, and the process is quick and painless. A urine sample is collected and then tested in one of a few ways:

• Dipstick test: A strip treated with chemicals is dipped into the urine. The strip changes color to give a quick estimate of urine concentration.

• Refractometer: A handheld device that uses light refraction to measure the density of urine compared to water. This method is more precise than a dipstick.

• Laboratory analysis: In some cases, a lab test provides the most accurate reading of urine specific gravity.

No matter the method, normal test results for urine specific gravity are reported as a number between 1.005 and 1.030, which your healthcare provider will interpret in the context of your overall health.

When You Should See a Healthcare Professional

An unusual urine specific gravity result on its own doesn’t always mean something is wrong. Temporary factors, like how much water you drank, exercise, or even certain foods, can affect the number. [1]

You should reach out to a healthcare professional if:

• Your USG results are consistently too high or too low, even after adjusting fluid intake.

• You notice ongoing symptoms like constant thirst, frequent urination, swelling, or unexplained fatigue.

• You have a history of kidney disease, diabetes, or other conditions that affect fluid balance.

• Your urinalysis shows other abnormal findings (such as protein, blood, or glucose in urine) along with unusual USG results.

A healthcare provider can put your results into context, run additional tests if needed, and help you understand the next steps.

Keep Your Kidneys Healthy

Urine specific gravity offers a quick snapshot of your hydration and kidney health, but it’s only one part of the bigger picture. Staying on top of your lab results can help you make informed choices and catch potential issues early.

With Everlywell, you can easily access at-home tests and get clear insights into what your numbers mean, giving you the confidence to take charge of your health. Get started with Everlywell here.

References

1. Specific gravity of urine. Cleveland Clinic. Published July 18, 2025. Accessed September 2nd, 2025. https://my.clevelandclinic.org/health/diagnostics/specific-gravity-of-urine.

2. Urine specific gravity. University of California, San Francisco. Published August 6, 2024. Accessed September 2nd, 2025. https://www.ucsfhealth.org/medical-tests/urine-specific-gravity-test.

3. Your Kidneys & How They Work. National Institute of Diabetes and Digestive and Kidney Diseases. Published August 12, 2025. Accessed September 2nd, 2025. https://www.niddk.nih.gov/health-information/kidney-disease/kidneys-how-they-work.

4. Stuempfle KJ, Drury DG. Comparison of 3 Methods to Assess Urine Specific Gravity in Collegiate Wrestlers. Journal of Athletic Training. 2003;38(4):315–319. Published in Gettysburg College Faculty Publications via the Cupola institutional repository. Accessed September 2, 2025. https://cupola.gettysburg.edu/healthfac/29/ https://cupola.gettysburg.edu/cgi/viewcontent.cgi?article=1028&context=healthfac

5. Urinalysis. Cleveland Clinic. https://my.clevelandclinic.org/health/diagnostics/17893-urinalysis. Published March 19, 2025.