Blood Urea: normal range and what it means
Short answer: The normal blood urea range is 15 – 43 mg/dL for adults. In SI units that is about 2.5 – 7.2 mmol/L. Labs differ a little, so also check the range printed on your report.
Check your value
Where does your blood urea sit?
Your result
Type the number from your lab report to see where it sits.
Calculators that use your blood urea
Upload your whole lab report and see every marker, with this value already in. Free, no account.
Add the rest of your reportWorked out in your browser. Nothing you type is sent or saved.
Information, not a diagnosis. Talk to a doctor about your result, and sooner if you feel unwell.
Urea in the blood — closely related to BUN.
Normal range
Adult reference range.
- Low< 15 mg/dL
- Normal15 – 43 mg/dL
- High≥ 43 mg/dL
Free calculator
BUN to creatinine ratio calculator
BUN/creatinine ratio = BUN (mg/dL) ÷ creatinine (mg/dL)
Source: Hosten AO. BUN and creatinine. In: Walker HK, Hall WD, Hurst JW, eds. Clinical Methods: The History, Physical, and Laboratory Examinations. 3rd ed. Boston: Butterworths; 1990. Chapter 193.
Only matters in mg/dL
From the same blood test
Your result
Enter the numbers from your lab report to see your result.
US labs print BUN (urea nitrogen); many others print urea, which is about 2.14 times bigger in mg/dL. In mmol/L the two are the same number. The calculator converts.
Worked out in your browser. Nothing you type is sent or saved.
A pointer, not a diagnosis. Talk to a doctor about your result, and sooner if you feel unwell.
What it measures
The same waste product as BUN, reported as whole urea rather than just its nitrogen. Which one you see depends on the lab’s convention, not on the test.
What moves it
The same picture as BUN — protein intake, hydration and kidney function — reported on a different scale.
How to bring it into range
Interpreted exactly like BUN, alongside creatinine and eGFR. Hydration before the draw affects it.
How fast it responds
Days.
Also reported as: urea
See where your own value lands
Upload a lab report and HealthOS reads all 88 markers, personalises every range to your sex and age, and tells you which ones actually need attention. Free, no account needed.
Check my blood testGet this marker explained for your own numbers
We’ll send you a short guide to reading this marker in context — what to check alongside it, and when a value is worth acting on.
One email about this marker. No spam, unsubscribe anytime.
We handle your details as described in our Privacy Policy.
Common questions
- What is the normal blood urea range?
- The normal blood urea range is 15 – 43 mg/dL for adults. In SI units that is about 2.5 – 7.2 mmol/L. Labs differ a little, so also check the range printed on your report.
- What does a high Blood Urea mean?
- A value above the reference band means Blood Urea is outside the range typical for a healthy adult. A single reading is rarely conclusive on its own — what matters is the trend across draws and the other markers around it, which is why HealthOS reads the whole panel together rather than one number at a time.
- How do I improve my Blood Urea?
- Interpreted exactly like BUN, alongside creatinine and eGFR. Hydration before the draw affects it.
Related markers
More in Kidney
Reference ranges are general-population guidance compiled from common clinical laboratories, not a diagnosis. Lab-to-lab ranges differ. Always read your results with your doctor.