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Urea in two units: the short answer
To convert urea from mg/dL to mmol/L, multiply by 0.1665. To go back from mmol/L to mg/dL, multiply by 6.006 (or divide by 0.1665). For example, 45 mg/dL × 0.1665 = 7.5 mmol/L. The converter above works in both directions and shows where the result sits against typical reference ranges.
What the test measures
Some laboratories, particularly in Europe, Latin America and parts of Asia, report the whole urea molecule in mg/dL rather than blood urea nitrogen (BUN). Urea has a molar mass of 60.06 g/mol, so 1 mmol/L of urea equals 6.006 mg/dL, and urea in mg/dL × 0.1665 gives mmol/L. This is different from BUN, which counts only the nitrogen in urea.
Why the units differ
Mixing up urea and BUN is a common source of error: urea in mg/dL is about 2.14 times the BUN value. If your report says 'BUN', use our BUN to urea converter instead; if it says 'urea' or 'ureia', use this one.
Where the factor comes from
The conversion factor comes from the molar mass (60.06 g/mol) and the volume units on each side. Laboratories may round the factor slightly differently, which can change the last digit but never the clinical meaning.
How to convert step by step
- Check the unit printed next to the result on your report – mg/dL or mmol/L.
- mg/dL → mmol/L: multiply by 0.1665.
- mmol/L → mg/dL: multiply by 6.006.
- Round to the same number of decimals your lab uses.
Worked example in reverse: 3.3 mmol/L × 6.006 = 19.8 mg/dL.
Urea conversion chart
| mg/dL | mmol/L |
|---|---|
| 10 | 1.7 |
| 15 | 2.5 |
| 20 | 3.3 |
| 25 | 4.2 |
| 30 | 5 |
| 40 | 6.7 |
| 45 | 7.5 |
| 50 | 8.3 |
| 60 | 10 |
| 80 | 13.3 |
| 100 | 16.7 |
| 150 | 25 |
| mmol/L | mg/dL |
|---|---|
| 1.7 | 10.2 |
| 2.5 | 15 |
| 3.3 | 19.8 |
| 4.2 | 25.2 |
| 5 | 30 |
| 6.7 | 40.2 |
| 7.5 | 45 |
| 8.3 | 49.8 |
| 10 | 60.1 |
| 13.3 | 79.9 |
| 16.7 | 100.3 |
| 25 | 150.2 |
Urea levels: what the numbers mean
| Category | mg/dL | mmol/L |
|---|---|---|
| Typical adult rangeAbout 2.5–7.1 mmol/L; varies by lab, age and diet | 15 – 43 | 2.5 – 7.2 |
| RaisedDehydration, high protein intake, GI bleeding or reduced kidney function | ≥ 43 | ≥ 7.2 |
Typical adult reference interval for serum urea. Urea is interpreted together with creatinine and eGFR, not on its own.
Typical adult reference interval for serum urea. Urea is interpreted together with creatinine and eGFR, not on its own.
Interpreting urea results
Urea is made in the liver when protein is broken down and is filtered out by the kidneys. Levels rise when you are dehydrated, after a high-protein meal, with bleeding in the upper gut, with corticosteroids, and when kidney function falls. Low urea is usually harmless and may reflect a low-protein diet, pregnancy or, less often, severe liver disease. Because so many non-kidney factors move urea, clinicians judge kidney function mainly from creatinine and eGFR.
A single result outside the reference range is common and often not significant on its own. Reference ranges are set so that about 1 in 20 healthy people fall outside them, and every laboratory sets its own limits for its method. Use the range printed on your report and discuss results with the clinician who ordered the test.
When to see a doctor
Contact your clinician if a result is flagged as abnormal and you have symptoms, if a value is far outside the range, or if results are changing over time. This page explains units; it cannot diagnose or replace medical advice.
Frequently asked questions
Is urea the same as BUN?
No. BUN measures only the nitrogen part of urea. Urea (mg/dL) = BUN (mg/dL) × 2.14, while both convert to the same mmol/L figure when you use the right factor.
What is 7 mmol/L urea in mg/dL?
7 × 6.006 = 42 mg/dL, near the upper end of a typical adult range.
Can I use this converter for any lab?
Yes for the unit conversion, which is fixed by chemistry. Reference ranges differ between labs and methods, so compare your converted value with your own lab's range.