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Ammonia in two units: the short answer
To convert ammonia from µg/dL to µmol/L, multiply by 0.587. To go back from µmol/L to µg/dL, multiply by 1.704 (or divide by 0.587). For example, 60 µg/dL × 0.587 = 35 µmol/L. The converter above works in both directions and shows where the result sits against typical reference ranges.
What the test measures
Blood ammonia is reported in µg/dL (mcg/dL) in the US and in µmol/L elsewhere. Ammonia (NH3) has a molar mass of 17.03 g/mol, so 1 µg/dL = 0.587 µmol/L and 1 µmol/L = 1.70 µg/dL.
Why the units differ
Ammonia is checked when confusion may be caused by liver failure or rare metabolic disorders. Published thresholds and clinical papers use both units.
Where the factor comes from
The conversion factor comes from the molar mass (17.03 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 – µg/dL or µmol/L.
- µg/dL → µmol/L: multiply by 0.587.
- µmol/L → µg/dL: multiply by 1.704.
- Round to the same number of decimals your lab uses.
Worked example in reverse: 12.0 µmol/L × 1.704 = 20.4 µg/dL.
Ammonia conversion chart
| µg/dL | µmol/L |
|---|---|
| 10 | 6 |
| 15 | 9 |
| 20 | 12 |
| 30 | 18 |
| 45 | 26 |
| 60 | 35 |
| 80 | 47 |
| 100 | 59 |
| 150 | 88 |
| 200 | 117 |
| µmol/L | µg/dL |
|---|---|
| 6 | 10.2 |
| 9 | 15.3 |
| 12 | 20.4 |
| 18 | 30.7 |
| 26 | 44.3 |
| 35 | 59.6 |
| 47 | 80.1 |
| 59 | 100.5 |
| 88 | 149.9 |
| 117 | 199.3 |
Ammonia levels: what the numbers mean
| Category | µg/dL | µmol/L |
|---|---|---|
| Typical adult rangeAbout 11–32 µmol/L; varies by lab | 15 – 45 | 9 – 26 |
| Raised | ≥ 45 | ≥ 26 |
Typical adult reference interval. Sample handling strongly affects ammonia.
Typical adult reference interval. Sample handling strongly affects ammonia.
Interpreting ammonia results
The liver turns ammonia into urea. When the liver fails or blood bypasses it, ammonia builds up and can contribute to hepatic encephalopathy. Even so, the ammonia level does not track symptoms closely, and guidelines for cirrhosis do not recommend routine repeat measurement to guide treatment. In newborns and children, high ammonia can signal inherited urea-cycle disorders and is treated as an emergency.
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
What is 50 µmol/L ammonia in µg/dL?
50 × 1.70 = 85 µg/dL.
Why was my ammonia test repeated?
Ammonia rises falsely if the sample sits warm, the tourniquet is tight or the fist is clenched. It should be drawn without a tourniquet if possible, kept on ice and tested quickly.
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.