SAAG Calculator

Q: What is the most common cause of high SAAG ascites?

Cirrhosis. It is the most common cause of ascites in the Western world. 1 Other high-SAAG causes are less common: Heart failure affecting the liver Massive liver metastases 1 Alcoholic hepatitis 6 Budd-Chiari syndrome (blocked liver veins) 6 Portal vein blood clot 6

Q: How do you tell heart failure ascites from cirrhosis ascites?

Both give a high SAAG, so albumin alone will not separate them. Doctors add the total protein in the belly fluid: Total protein above 2.5 g/dL supports a heart cause. 1 Total protein under 2.5 g/dL with a high SAAG points to cirrhosis. 5 A blood BNP test and an echocardiogram can help check for a heart cause. 6

Q: Does an albumin infusion affect the SAAG?

It can. Albumin given into a vein raises the serum albumin. Since the SAAG is serum albumin minus ascites albumin, a higher serum value can make the gap look wider. Blood for the test should be drawn at the same time as the tap. 1 If the two samples are hours or days apart, the number may not be reliable.

Q: Can a person with cirrhosis have a low SAAG?

Yes, but it is uncommon. 5 In the study that compared the gradient with the older protein test, the gradient sorted ascites correctly 96.7% of the time. 2 Common reasons for a low result in cirrhosis: Serum albumin is so low (under about 1.1 g/dL) that a wide gap is not possible Blood and fluid were taken days apart Lab or unit error Repeating the test often clears it up. 5

Q: What is mixed ascites?

Mixed ascites means two causes at once, such as cirrhosis plus cancer or cirrhosis plus tuberculosis. The SAAG can still be high, because portal hypertension is still there. A high fluid protein or cancer cells on cytology can be clues that something else is going on too. 5

Q: What other tests are run on ascitic fluid?

A first tap usually includes: Cell count with differential. More than 250 neutrophils per mm³ points to spontaneous bacterial peritonitis (SBP). 1 A count this high can also come from another infection or inflammation inside the belly, such as diverticulitis or cholecystitis, which is treated differently. 1 Culture. Done for people in hospital, or when infection is suspected. The fluid goes into blood culture bottles at the bedside before antibiotics start. 1 Total protein. Helps sort heart vs. liver causes Albumin. For the SAAG 1 Extra tests, added when needed: glucose, LDH, amylase (pancreas), cytology (cancer), and adenosine deaminase or AFB culture (TB).

Q: Does spontaneous bacterial peritonitis change the SAAG?

No. In SBP the SAAG stays high because the underlying cause is still portal hypertension. The infection shows up in the cell count , not in the albumin gradient. A neutrophil count of more than 250 per mm³ means antibiotics should start right away, even before culture results return. 1

Q: Can a bloody tap change the SAAG?

Yes. Blood carries albumin, so a bloody sample can raise the albumin in the fluid and make the gradient look smaller than it really is. Tell the lab if the tap was traumatic. Repeating the tap at a different spot usually gives a clean sample.

Q: How is ascitic fluid albumin collected?

Through a paracentesis. A doctor numbs a small spot on the lower belly, on the left or right side. Ultrasound is often used to guide the needle to the fluid. A thin needle draws the fluid out. A diagnostic tap usually takes 10 to 20 mL of fluid, enough for the albumin test, the cell count and cultures.

Q: What SAAG do you see in cancer-related ascites?

Usually low, under 1.1 g/dL, when cancer coats the lining of the belly (peritoneal carcinomatosis). 1 That is under 11 g/L. The exception: if cancer has spread widely through the liver, the SAAG can be high. 1 Cytology on the fluid looks for cancer cells. It finds them in most cases of cancer on the lining of the belly, but rarely in cancer that starts in the liver (hepatocellular carcinoma) in someone with cirrhosis. 5

Introduction

The SAAG calculator works out the Serum-Ascites Albumin Gradient. This is the difference between the albumin in your blood and the albumin in the fluid in your belly (ascites). Doctors use this number to find out why the fluid built up.

The math is simple: SAAG = serum albumin − ascites albumin. But the answer tells you a lot. A SAAG of 1.1 g/dL or higher points to high pressure in the portal vein, as in cirrhosis or heart failure, while a SAAG under 1.1 g/dL points to other causes, like cancer on the lining of the belly or tuberculosis.¹ In g/L, the cut-off is 11. The test is about 97% accurate at telling these two groups apart.¹ In the study behind it, the gradient was right 96.7% of the time, against 55.6% for the old "transudate vs. exudate" protein test.²

Enter both albumin values and pick your units. The tool accepts g/dL or g/L, and it converts them for you, so mixed units will not give you a wrong answer. The result appears right away, along with a step-by-step solution and a chart that shows both values next to the 11 g/L cut-off.

Draw both samples at the same time for the best result.¹ This calculator is a learning and support tool. It does not replace your doctor's judgment or a full workup.

How to use our SAAG Calculator

Enter two lab values: the albumin in your blood and the albumin in your ascites fluid. The SAAG calculator subtracts one from the other and shows the serum-ascites albumin gradient in g/L and g/dL, plus what that result means.

Serum Albumin: Type the albumin level from the blood test taken at the same time as the tap. Pick g/dL or g/L from the drop-down next to the box. The normal range is 3.4 to 5.4 g/dL (34 to 54 g/L).³

Ascites Albumin: Type the albumin level measured in the ascitic fluid sample. Pick g/dL or g/L for this value too. There is no normal range for this one.

Chart & table units: Choose g/L or g/dL to set how the bar chart and the value table show the numbers. This does not change your answer, only how it is displayed.

The result updates as you type. Press Calculate to refresh it, or Reset to start over. A SAAG of 1.1 g/dL or higher points to portal hypertension, and a lower SAAG points to other causes.¹

What Is the Serum-Ascites Albumin Gradient (SAAG)?

Ascites is fluid that builds up in the belly. The SAAG test helps doctors find out why that fluid is there. It compares the amount of albumin (a protein made by the liver) in the blood with the amount of albumin in the belly fluid. A gap of 1.1 g/dL or more points to high pressure in the portal vein.¹ That is the large vein that carries blood to the liver.

How SAAG Works

The formula is simple:

SAAG = Serum albumin − Ascites albumin

Both samples should be taken at the same time.¹ Blood is drawn for the serum albumin. Belly fluid is taken during a paracentesis, a procedure where a thin needle removes fluid from the abdomen. Labs report albumin in g/dL or g/L. 1 g/dL equals 10 g/L.

What the Numbers Mean

The cutoff is 1.1 g/dL.¹ That is 11 g/L.

SAAG 11 g/L or higher (high gradient): Portal hypertension is likely. Causes include cirrhosis, heart failure affecting the liver, and cancer spread widely through the liver.¹ Alcoholic hepatitis and Budd-Chiari syndrome also raise portal pressure.⁶
SAAG under 11 g/L (low gradient): Portal hypertension is unlikely. Causes include cancer spread to the lining of the belly and tuberculosis.¹ Pancreatitis and nephrotic syndrome are other causes.⁶

Why Doctors Use It

SAAG is about 97% accurate at sorting ascites into these two groups.¹ The older transudate-exudate test based on total protein sorted only 55.6% correctly, and its authors said it should be dropped.² Knowing the group narrows down the cause fast and guides treatment, such as salt limits and diuretics for advanced liver disease, or cancer care for malignant ascites.

Things to Keep in Mind

SAAG tells you if portal hypertension is present. It does not name the exact disease.
A low result in someone thought to have cirrhosis should be repeated, since a second tap often shows a high gradient.⁵
A person can have more than one cause at once, such as cirrhosis plus cancer.
A negative result (ascites albumin higher than serum albumin) is a reason to check the report for a mix-up in samples or units.
Ascitic fluid should also be checked for cell count, culture, and total protein to look for infection like spontaneous bacterial peritonitis.¹

Formulas used

Unit conversion to g/L

C_{\text{g/L}} = C_{\text{g/dL}} \times 10

Serum-Ascites Albumin Gradient (g/L) ¹

\text{SAAG}_{\text{g/L}} = \text{Serum Albumin}_{\text{g/L}} - \text{Ascites Albumin}_{\text{g/L}}

SAAG expressed in g/dL

\text{SAAG}_{\text{g/dL}} = \frac{\text{SAAG}_{\text{g/L}}}{10}

Interpretation threshold ¹

\text{SAAG} \ge 11\ \text{g/L}\ (1.1\ \text{g/dL}) \Rightarrow \text{portal hypertension likely};\quad \text{SAAG} < 11\ \text{g/L} \Rightarrow \text{portal hypertension unlikely}

Frequently asked questions

What is the most common cause of high SAAG ascites?

Cirrhosis. It is the most common cause of ascites in the Western world.¹

Other high-SAAG causes are less common:

Heart failure affecting the liver
Massive liver metastases¹
Alcoholic hepatitis⁶
Budd-Chiari syndrome (blocked liver veins)⁶
Portal vein blood clot⁶

How do you tell heart failure ascites from cirrhosis ascites?

Both give a high SAAG, so albumin alone will not separate them. Doctors add the total protein in the belly fluid:

Total protein above 2.5 g/dL supports a heart cause.¹
Total protein under 2.5 g/dL with a high SAAG points to cirrhosis.⁵

A blood BNP test and an echocardiogram can help check for a heart cause.⁶

Does an albumin infusion affect the SAAG?

It can. Albumin given into a vein raises the serum albumin. Since the SAAG is serum albumin minus ascites albumin, a higher serum value can make the gap look wider. Blood for the test should be drawn at the same time as the tap.¹

If the two samples are hours or days apart, the number may not be reliable.

Can a person with cirrhosis have a low SAAG?

Yes, but it is uncommon.⁵ In the study that compared the gradient with the older protein test, the gradient sorted ascites correctly 96.7% of the time.² Common reasons for a low result in cirrhosis:

Serum albumin is so low (under about 1.1 g/dL) that a wide gap is not possible
Blood and fluid were taken days apart
Lab or unit error

Repeating the test often clears it up.⁵

What is mixed ascites?

Mixed ascites means two causes at once, such as cirrhosis plus cancer or cirrhosis plus tuberculosis.

The SAAG can still be high, because portal hypertension is still there. A high fluid protein or cancer cells on cytology can be clues that something else is going on too.⁵

What other tests are run on ascitic fluid?

A first tap usually includes:

Cell count with differential. More than 250 neutrophils per mm³ points to spontaneous bacterial peritonitis (SBP).¹ A count this high can also come from another infection or inflammation inside the belly, such as diverticulitis or cholecystitis, which is treated differently.¹
Culture. Done for people in hospital, or when infection is suspected. The fluid goes into blood culture bottles at the bedside before antibiotics start.¹
Total protein. Helps sort heart vs. liver causes
Albumin. For the SAAG¹

Extra tests, added when needed: glucose, LDH, amylase (pancreas), cytology (cancer), and adenosine deaminase or AFB culture (TB).

Does spontaneous bacterial peritonitis change the SAAG?

No. In SBP the SAAG stays high because the underlying cause is still portal hypertension. The infection shows up in the cell count, not in the albumin gradient.

A neutrophil count of more than 250 per mm³ means antibiotics should start right away, even before culture results return.¹

Can a bloody tap change the SAAG?

Yes. Blood carries albumin, so a bloody sample can raise the albumin in the fluid and make the gradient look smaller than it really is.

Tell the lab if the tap was traumatic. Repeating the tap at a different spot usually gives a clean sample.

How is ascitic fluid albumin collected?

Through a paracentesis. A doctor numbs a small spot on the lower belly, on the left or right side. Ultrasound is often used to guide the needle to the fluid. A thin needle draws the fluid out.

A diagnostic tap usually takes 10 to 20 mL of fluid, enough for the albumin test, the cell count and cultures.

What SAAG do you see in cancer-related ascites?

Usually low, under 1.1 g/dL, when cancer coats the lining of the belly (peritoneal carcinomatosis).¹ That is under 11 g/L.

The exception: if cancer has spread widely through the liver, the SAAG can be high.¹ Cytology on the fluid looks for cancer cells. It finds them in most cases of cancer on the lining of the belly, but rarely in cancer that starts in the liver (hepatocellular carcinoma) in someone with cirrhosis.⁵

Does the SAAG need to be repeated?

Usually not. In cirrhosis it is measured on the first tap for new ascites, and is not needed again when the fluid comes back.¹ One exception is a low result in someone thought to have cirrhosis, which should be repeated.⁵

Repeat taps are still done to check for infection or to drain large amounts of fluid, but the albumin gradient does not need rechecking each time.

What is the SAAG in tuberculous peritonitis?

Low, under 1.1 g/dL.¹ That is under 11 g/L. The fluid almost always has a high total protein, and most often many lymphocytes.⁷

TB is often missed by a culture of the fluid, so an adenosine deaminase (ADA) test on the fluid can help.⁷ TB in someone who also has cirrhosis can still show a high SAAG.⁷

What are the signs of ascites?

Common signs:

Belly swelling and bloating
Belly pain
Shortness of breath when there is a lot of fluid⁴
Weight gain⁵
Feeling full after small meals⁵

A small amount of fluid may cause no symptoms.⁴

New belly pain, fever, or confusion in someone with ascites needs urgent care, since these can mean infection.⁴⁵

Sources

Biggins SW, Angeli P, Garcia-Tsao G, Ginès P, Ling SC, Nadim MK, et al. Diagnosis, evaluation, and management of ascites, spontaneous bacterial peritonitis and hepatorenal syndrome: 2021 practice guidance by the American Association for the Study of Liver Diseases. Hepatology. 2021;74(2):1014-1048. doi:10.1002/hep.31884. Accessed September 26, 2026.

Runyon BA, Montano AA, Akriviadis EA, Antillon MR, Irving MA, McHutchison JG. The serum-ascites albumin gradient is superior to the exudate-transudate concept in the differential diagnosis of ascites. Annals of Internal Medicine. 1992;117(3):215-220. doi:10.7326/0003-4819-117-3-215. Accessed September 26, 2026.

Albumin blood test. MedlinePlus, U.S. National Library of Medicine. Accessed September 26, 2026.

Ascites. MedlinePlus, U.S. National Library of Medicine. Accessed September 26, 2026.

Hernaez R, Hamilton JP. Unexplained ascites. Clinical Liver Disease. 2016;7(3):53-56, History and Physical Examination; Differential Diagnosis of Ascites. doi:10.1002/cld.537. Accessed November 11, 2026.

Lippert WC, Lee EY, Mirrakhimov AE. A woman, age 35, with new-onset ascites. Cleveland Clinic Journal of Medicine. 2019;86(4):257-262, pp. 258-259 (serum-ascites albumin gradient and Figure 1). doi:10.3949/ccjm.86a.17082. Accessed November 11, 2026.

Koff A, Azar MM. Diagnosing peritoneal tuberculosis. BMJ Case Reports. 2020;13(2):e233131, Discussion. doi:10.1136/bcr-2019-233131. Accessed November 11, 2026.

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