N1-Methylnicotinamide Unit Converter
N1-Methylnicotinamide Unit Converter
Convert N1-methylnicotinamide between mg/L, µg/L and µmol/L. This page converts at the mass of the CATION, 137.162 — not the chloride salt at 172.61 that most reference standards are supplied as, because using the salt’s mass understates a molar result by about 21%.
N1-methylnicotinamide converter
Mass ⇄ molarUrinary N1-methylnicotinamide 5.000 mg/L, reported as a concentration on a spot sample
Which mass, and why it matters by a fifth
mg/L = µmol/L ÷ 7.29065
- 7.29065
- derived from the cation mass: one mg/L is 0.001 g/L, and 0.001 ÷ 137.162 × 10⁶ = 7.29065 µmol/L
- 137.162
- C7H9N2O⁺, the measurand — a permanently charged quaternary pyridinium cation, summed from the IUPAC 2021 standard atomic weights: carbon 7 × 12.011 = 84.077, hydrogen 9 × 1.008 = 9.072, nitrogen 2 × 14.007 = 28.014, oxygen 15.999. PubChem CID 457 prints 137.16. The electron mass is 0.00055 and falls below the last printed digit
- 172.61
- the CHLORIDE SALT, C7H9ClN2O — 137.162 + 35.45 for the chloride counter-ion. Most commercial reference standards are supplied as this salt and much of the older literature quotes it. It is not the measurand, because the chloride dissociates in solution and is not what the assay detects
- the 21%
- a molar result is mass divided by molar mass, so dividing by the larger 172.61 instead of 137.162 gives a factor of 137.162 ÷ 172.61 = 0.795 — that is, 20.5% low, which rounds to a fifth. In the other direction, a molar figure converted to mass with the salt’s weight comes out 25.8% high
- NMN is two molecules
- the abbreviation NMN is used both for N1-methylnicotinamide, this page, and for nicotinamide mononucleotide, C11H15N2O8P at 334.22 — an NAD⁺ precursor sold as a supplement and studied in ageing research, with no role in niacin status assessment. They are unrelated, differ by 2.4-fold in mass, and the only defence is to write the name out
- what this page cannot do
- urinary NMN is usually reported normalised to creatinine, as µmol/mmol creatinine or mg/g creatinine, or as an excretion over a timed collection. Neither is a concentration and neither can be derived from one without the creatinine or the volume, which this page does not have. It converts the concentration only
Worked example
Urinary N1-methylnicotinamide 5.000 mg/L, reported as a concentration on a spot sample
5.000 × 7.29065 = 36.45 µmol/L, using the cation mass of 137.162
The same 5.000 mg/L put through the chloride salt's 172.61 would give 28.97 µmol/L — 20.5% lower, and nothing about the number looks wrong
5.000 mg/L is also 5,000 µg/L and 5,000 ng/mL; those three are the same quantity written three ways and the ladder above shows them together
This is still a concentration. To grade niacin status it has to become an excretion — a 24-hour output, or a ratio to urinary creatinine — and that needs the volume or the creatinine, neither of which is on this page
And it is only half the test that matters: the informative figure is the ratio of 2-pyridone to NMN, which needs the 2-pyridone measured on the same sample
Three masses that get used for this one analyte
| Species | Formula | Mass | Use it? |
|---|---|---|---|
| N1-methylnicotinamide cation | C7H9N2O⁺ | 137.162 | Yes — this is the measurand and the mass this page converts with |
| N1-methylnicotinamide chloride | C7H9ClN2O | 172.61 | No — the salt the standard is supplied as. Understates a molar result by 20.5% |
| Nicotinamide mononucleotide | C11H15N2O8P | 334.22 | No — a different molecule that shares the abbreviation NMN |
Where N1-methylnicotinamide sits in niacin assessment
| Measurement | What it tells you |
|---|---|
| Plasma niacin (nicotinic acid) | Very little — it does not grade status, which is why the niacin (vitamin B3) converter prints no interval |
| Urinary N1-methylnicotinamide | The major urinary catabolite; falls in niacin deficiency, but moves with recent intake and with urine concentration |
| Urinary 2-pyridone (N1-methyl-2-pyridone-5-carboxamide) | The second catabolite, and the more sensitive of the two to falling intake |
| 2-pyridone : NMN ratio | The established index. It falls as niacin status falls, and being a ratio of two analytes from the same sample it is largely free of the urine-concentration problem that afflicts either alone |
| Erythrocyte NAD : NADP ratio | The niacin number; an alternative functional index |
The catabolite, the ratio, and the two masses
N1-methylnicotinamide is the principal urinary end product of niacin metabolism. Nicotinamide is methylated by nicotinamide N-methyltransferase to give the quaternary pyridinium cation this page converts, and that cation is either excreted intact or oxidised further to N1-methyl-2-pyridone-5-carboxamide, universally shortened to 2-pyridone. Measuring the two together and taking the ratio is the classical way of assessing niacin status, and the reason it is done as a ratio is that the 2-pyridone falls faster than the NMN as intake declines, so the ratio moves further than either number and is not confounded by how dilute the urine is.
The clinical context is niacin and tryptophan status, and the two are the same subject. Tryptophan is converted to niacin equivalents through the kynurenine pathway at a ratio of roughly 60 mg of tryptophan to 1 mg of niacin, so a niacin deficiency can arise from a shortfall of either. That is why pellagra appears in Hartnup disease, where neutral amino acid transport fails and tryptophan is lost; in carcinoid syndrome, where tryptophan is diverted into serotonin; and on isoniazid or with vitamin B6 deficiency, either of which can block the pathway, since the kynureninase step is pyridoxal-phosphate dependent. The tryptophan converter and the niacin (vitamin B3) converter are the companion pages, and the second of those explains why a plasma niacin level is not the test.
Now the mass. The measurand is the cation, C7H9N2O⁺, at 137.162 Da. It carries a permanent positive charge on the ring nitrogen, so in solution and in the mass spectrometer it exists as the cation and the counter-ion is incidental. Commercial reference standards, however, are almost always supplied as the chloride, at 172.61 Da, and a great deal of the published literature quotes that figure because it is what was weighed out. Using 172.61 to convert a mass concentration to a molar one divides by too large a number: the result is 137.162 ÷ 172.61 = 0.795 of the correct value, or 20.5% low. That matters twice over — once when a result is converted, and again when a calibrator is prepared, because a gram of the chloride salt contains only 0.795 g of the cation. A standard weighed as though the salt were pure NMN is 20.5% under-strength, and every result run against it is 25.8% high.
One more thing about the abbreviation. NMN has, unhelpfully, become the common abbreviation for nicotinamide mononucleotide, a nucleotide NAD⁺ precursor of mass 334.22 that is sold as a supplement and studied in ageing research. It has nothing to do with niacin status assessment and shares neither structure nor mass with the analyte on this page. If a document says NMN and the mass is in the three hundreds, it is the mononucleotide. Writing the name out is the only reliable fix.
Frequently asked questions
What is the molecular weight of N1-methylnicotinamide?
137.162 Da for the cation, C7H9N2O⁺, which is the measurand. That is the sum of the IUPAC 2021 standard atomic weights: seven carbons at 12.011, nine hydrogens at 1.008, two nitrogens at 14.007 and one oxygen at 15.999. The chloride salt, which most reference standards are supplied as, is 172.61 — the cation plus a chloride at 35.45. PubChem CID 457 prints both.
Which mass should I convert with, 137.162 or 172.61?
137.162, the cation, because that is the species the assay measures and the one the result refers to. Using 172.61 divides by too large a molar mass and gives a molar result that is 20.5% low — a factor of 0.795. Converting the other way, from molar to mass, the salt’s weight makes the answer 25.8% high. The only place 172.61 is the right number is on a balance, when you are weighing the salt out to prepare a standard.
Is NMN the same as nicotinamide mononucleotide?
No. They are unrelated molecules that share an abbreviation. N1-methylnicotinamide is the urinary niacin catabolite on this page, at 137.162. Nicotinamide mononucleotide is C11H15N2O8P at 334.22, a nucleotide precursor of NAD⁺ taken as a supplement and studied in ageing research. Neither is used in place of the other and the masses differ 2.4-fold, so a conversion done with the wrong one is not subtly wrong.
How is urinary N1-methylnicotinamide used to assess niacin status?
Rarely on its own. The established index is the ratio of urinary 2-pyridone to N1-methylnicotinamide, both measured on the same sample, because the 2-pyridone falls further than the NMN as niacin intake declines and a ratio cancels out how concentrated the urine is. Where NMN is reported alone it is normalised to urinary creatinine or expressed as a 24-hour excretion, and a bare concentration — which is what this page converts — is the least interpretable form of it.
Why does this page print no reference interval?
Because the quantity it converts is not the quantity that gets graded. Published thresholds for niacin status are expressed as excretion rates, as ratios to creatinine, or as the 2-pyridone-to-NMN ratio, and none of those can be derived from a concentration without the urine volume or the creatinine, which this page does not have. Printing a concentration interval would invite a reader to grade a result against a threshold that does not apply to it.
Why is this page filed under amino acids rather than vitamins?
Because the site’s own taxonomy puts it there, and because the biology supports it: the analyte’s clinical meaning runs through tryptophan and the kynurenine pathway as much as through dietary niacin. The niacin (vitamin B3) converter sits in the vitamins and trace elements category and the tryptophan converter sits here, and the two pages are linked from this one.
Related calculators
References
- Shibata K, Matsuo H. Correlation between niacin equivalent intake and urinary excretion of its metabolites, N1-methylnicotinamide, N1-methyl-2-pyridone-5-carboxamide, and N1-methyl-4-pyridone-3-carboxamide, in humans consuming a self-selected food intake. Am J Clin Nutr. 1989;50(1):114–119. doi:10.1093/ajcn/50.1.114
- Jacob RA, Swendseid ME, McKee RW, Fu CS, Clemens RA. Biochemical markers for assessment of niacin status in young men: urinary and blood levels of niacin metabolites. J Nutr. 1989;119(4):591–598. doi:10.1093/jn/119.4.591 — the source of the 2-pyridone to N1-methylnicotinamide ratio as the preferred index.
- Institute of Medicine. Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline. Washington DC: National Academies Press; 1998. Chapter 6, Niacin — the 60 mg tryptophan to 1 mg niacin equivalence and urinary metabolite excretion as the status indicator.
- Fukuwatari T, Shibata K. Nutritional aspect of tryptophan metabolism. Int J Tryptophan Res. 2013;6(Suppl 1):3–8. doi:10.4137/IJTR.S11588
- PubChem Compound Summary CID 457, 1-Methylnicotinamide. National Center for Biotechnology Information. Cation C7H9N2O⁺, 137.16; chloride salt C7H9ClN2O, 172.61. Accessed 2026.
- IUPAC Commission on Isotopic Abundances and Atomic Weights. Standard Atomic Weights 2021: C 12.011, H 1.008, N 14.007, O 15.999, Cl 35.45, P 30.974.
- data/_factors.json, analyte
n1_methylnicotinamide: mw 137.162; "The measurand is the CATION … Reference standards and much of the literature quote the CHLORIDE salt at 172.61, and using the salt’s mass would understate a molar result by 21%."
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