Nanomolar to Molar Converter
Common Conversions
| nM | M |
|---|---|
| 0.1 | 1e-10 |
| 1 | 1e-9 |
| 10 | 1e-8 |
| 100 | 1e-7 |
| 1000 | 0.000001 |
| 5000 | 0.000005 |
| 10000 | 0.00001 |
| 100000 | 0.0001 |
| 1000000 | 0.001 |
| 10000000 | 0.01 |
| 100000000 | 0.1 |
| 1000000000 | 1 |
Why this conversion matters in chemistry
Pharmacology papers report binding and inhibition in nanomolar, but stock-solution math and most physical-chemistry equations want concentrations in M. A kinase inhibitor with a 10 nM IC50 is working at 1 × 10⁻⁸ M, which is the number that has to go into a Kd × concentration calculation or a Beer-Lambert absorbance estimate. Dividing by 10⁹ is the routine that lets a literature potency line up with a dilution scheme from a solid sample. The other direction of the same arithmetic tells you how many molecules of drug actually reach the target: 1 nM in a 100 µL assay well is still roughly 6 × 10¹⁰ molecules, which is never as few as the nanomolar label makes it feel.
Formula
Where the factor comes from
Two definitions stack here, and neither one is measured. Molar is shorthand for moles per liter, the liter having been exactly one cubic decimeter since 1964, so M resolves to mol/dm³ with no experimental input anywhere. Nano is a stipulated decimal multiplier of 10⁻⁹ attached to that whole symbol. Put them together and 1 nM = 10⁻⁹ mol/dm³, exact in the strict sense — a stipulation rather than a result, indifferent to the solute's identity, to the solvent, and to the value of Avogadro's constant. What is not definitional is the volume the concentration refers to. Molarity is built on the volume of the finished solution, and solutions expand when warmed, so an M figure carries an implicit temperature. The arithmetic loses nothing; the quantity is only as fixed as the flask's temperature was.
Precision and significant figures
The factor being exact, every digit in the answer arrived with the nanomolar figure, and at this scale there are rarely more than two of them. An IC50 or Kd from nonlinear regression usually carries a confidence interval spanning a factor of two, so writing it out as 1.27 × 10⁻⁸ M dresses a fitted parameter as a measurement. Worth noting what nanomolar means for methods that read M directly: Beer-Lambert on a strongly absorbing chromophore, ε near 10⁴ M⁻¹cm⁻¹ in a 1 cm cell, puts 1 nM at an absorbance of 10⁻⁵, which sits below the photometric noise floor of even a well-behaved spectrophotometer. Nanomolar numbers come from fluorescence, radioligand counting or mass spectrometry, and inherit those methods' precision.
Worked Examples
One nanomolar — the definition line, and a reasonable Kd for a well-optimized binder.
One micromolar in M units, the number that typically starts a dose-response titration.
A reasonable IC50 for a moderately potent inhibitor in a biochemical assay.
The sort of concentration endogenous steroid hormones run at in circulating plasma.
Common mistakes
Slipping a decade in the exponent
The exponent is minus nine plus the base-ten logarithm of the nanomolar figure, so 250 nM is 2.5 × 10⁻⁷ M and not 2.5 × 10⁻⁸. Neither version looks wrong sitting alone on a page. Anchor on round numbers instead: single-digit nanomolar lands near 10⁻⁹ M, hundreds of nanomolar near 10⁻⁷ M.
p-scale potencies are already in M
A pIC50 or pKd is the negative base-ten logarithm of a concentration in mol/L, never of a nanomolar figure. pIC50 7.5 means 3.2 × 10⁻⁸ M, or 32 nM; reading that antilog as though it were already nanomolar and then applying the 10⁻⁹ factor on top lands nine decades away. Take the p-value to M first, and convert to nM only afterward.
Millimolar stock to nanomolar in one step
Writing 10 nM as 10⁻⁸ M beside a 10 mM DMSO stock makes the span visible: six decades. That is not one pipetting operation. Attempting it means a fraction of a microliter into tens of milliliters, with solvent carryover and surface losses both working against you. Two or three serial stages is the honest route.