Nanomolar to Micromolar Converter
Common Conversions
| nM | µM |
|---|---|
| 0.1 | 0.0001 |
| 0.5 | 0.0005 |
| 1 | 0.001 |
| 5 | 0.005 |
| 10 | 0.01 |
| 50 | 0.05 |
| 100 | 0.1 |
| 250 | 0.25 |
| 500 | 0.5 |
| 1000 | 1 |
| 5000 | 5 |
| 10000 | 10 |
Why this conversion matters in chemistry
Nanomolar is where most drug potency numbers live; micromolar is where most enzyme assays are run. So this conversion comes up almost every time you're comparing a published Ki with the concentration you're about to put on a plate. The arithmetic is just a divide by a thousand — 500 nM is 0.5 µM — but the mental translation matters more than the math. A 1 nM binder is genuinely tight; a 1 µM binder is respectable but well below the threshold for most modern drug campaigns. Getting fluent with the step makes papers faster to read.
Formula
Where the factor comes from
The prefix attaches to the mole, not to the liter — worth being deliberate about, since nM means 10⁻⁹ mol per liter and never one mole per 10⁹ liters. With that settled, the derivation is a single line: nano is 10⁻⁹ and micro is 10⁻⁶, both fixed by resolution of the General Conference on Weights and Measures rather than by measurement, so their ratio is exactly 10⁻³. Divide a nanomolar figure by 1000 and you have the same physical quantity written in micromolar. Prefixes may not be stacked either. Older literature did write compounded forms — millimicro for what is now nano — and the SI retired the construction rather than its meaning, so a millimicromolar in an old paper is simply a nanomolar. The factor is definitional, permanent, and carries no uncertainty whatsoever.
Precision and significant figures
Dividing by an exact 1000 shifts the decimal point and leaves the figure count alone, so 640 nM is 0.640 µM and dropping to 0.64 µM discards information the measurement paid for. The interesting question at this scale is where the nanomolar figure came from in the first place. A value weighed and diluted into volumetric glassware can support three figures; a value read off a standard curve near its lower end is doing well to give two, since the curve's own scatter dominates that region. Potency numbers deserve particular skepticism — an IC50 fitted from a dose-response series often carries a confidence interval spanning a factor of two, which makes a three-figure nanomolar value a formatting choice rather than a result.
Worked Examples
A respectable Ki for a mid-stage enzyme inhibitor — enough affinity to matter, enough room left to optimize.
The kind of Kd you see for a tuned-up kinase inhibitor or a well-raised antibody.
A clean anchor point. This is roughly where most primary screening plates sit.
Where a lot of endogenous signaling molecules operate — receptor ligands, tight-binding peptides, that neighborhood.
Common mistakes
Exponent slipping by three in scientific notation
500 nM and 0.5 µM are both 5 × 10⁻⁷ M, and the recurring error is writing the micromolar form as 5 × 10⁻⁶ M because the µ suggests a −6 belongs somewhere. The prefix exponent applies to the whole quantity, not to the mantissa sitting in front of it. Convert once to plain molar and check the exponent there.
Adsorption thins the nanomolar solution
Peptides, proteins and lipophilic small molecules stick to plastic and glass, and at low nanomolar concentrations the fraction lost to tube and tip walls stops being negligible. The micromolar figure you calculated describes what was added, not what stayed free in solution. A dilution series that flattens at its low end is often reporting adsorption rather than saturation.
Published potency compared without converting
A paper reports a Ki of 40 nM, the plate was dosed at 10 µM, and the two get set side by side as though they were near neighbors. They differ by a factor of 250. Reading affinity data against working concentrations without putting both into one unit is how an assay ends up running hundreds of fold above the range it meant to probe.