Picomolar to Micromolar Converter
Common Conversions
| pM | µM |
|---|---|
| 1 | 0.000001 |
| 10 | 0.00001 |
| 100 | 0.0001 |
| 1000 | 0.001 |
| 10000 | 0.01 |
| 100000 | 0.1 |
| 1000000 | 1 |
| 5000000 | 5 |
| 10000000 | 10 |
| 100000000 | 100 |
| 1000000000 | 1000 |
| 10000000000 | 10000 |
Why this conversion matters in chemistry
Picomolar and micromolar live at opposite ends of the concentration ladder, and crossing between them takes a minute to get comfortable with. One micromolar is a million picomolar (µM = pM × 10⁻⁶), so a 500 pM antibody stock works out to 0.0005 µM — small enough that you rarely work with it directly, which is more or less the point. Picomolar concentrations come up when a binding affinity is tight enough to matter: a good antibody–antigen interaction, a kinase inhibitor that actually behaves in cells. Micromolar is where you spend most of your bench time. Converting between the two is how you sanity-check whether a literature Kd actually lines up with the dose you're about to add.
Formula
Where the factor comes from
Both sides are mol/L wearing a prefix, so the liter underneath cancels and the entire factor is prefix arithmetic. Pico is 10⁻¹², micro is 10⁻⁶, each stipulated by resolution of the General Conference on Weights and Measures rather than determined by experiment, so 10⁻¹² ÷ 10⁻⁶ = 10⁻⁶ exactly. One micromolar is one million picomolar, and no measured quantity appears anywhere in the chain. The liter itself has a less tidy history than that suggests: it is merely tolerated alongside SI, and it has been defined as exactly one cubic decimeter only since 1964. Before that it was pinned to the volume occupied by a kilogram of water at its density maximum, making the old liter about 1.000028 dm³ — a discrepancy that mattered for careful volumetric work of the period, and that cancels here along with everything else.
Precision and significant figures
Six decades is more than decimal notation handles gracefully. 0.0005 µM and 500 pM state the same fact, but the first buries its one digit behind three zeros, and a miscount there is a clean factor of ten. Significant figures are easier to see, and to keep, on the picomolar side. The factor contributes no uncertainty of its own, so figures in equals figures out. Whether you had those figures is a separate question. A micromolar working solution weighed into a volumetric flask can honestly support three or four; a picomolar value read off a fitted potency curve rarely supports more than two. Convert at full precision and round once, at the end.
Worked Examples
A million picomolar lands you at one micromolar — the clean anchor point for this scale.
The kind of Kd you'd see for a well-optimized antibody against its antigen, expressed in the units you'd actually dose a cell culture with.
One nanomolar, written two different ways. Worth keeping this equivalence in your head — it comes up constantly when reading across fields.
Halfway-decent hit concentration for an early-stage inhibitor in a cellular assay.
Common mistakes
The micro prefix mistaken for milli
µ has no key of its own, so it gets typed as u, collapsed to a question mark in an ASCII export, or handwritten in a way that reads as m. Milli and micro are a thousandfold apart, and a tube labeled 0.0005 mM instead of 0.0005 µM overstates itself by that much while looking entirely ordinary. Check the character whenever a label has changed hands.
Spreadsheet display rounding erases the value
A column formatted to three decimal places shows a picomolar concentration expressed in µM as 0.000. The stored number is intact; the printed one is gone. Anyone reading the sheet, or pasting it into a figure, now has a column of zeros. Keep low concentrations in picomolar for display, or set the cell format to scientific notation before sharing.
A millionfold dilution attempted in one step
Getting from a micromolar stock to a picomolar working solution spans 10⁶, which as a single transfer would mean something like one microliter into a liter. Nobody pipettes that accurately. It has to be built as two or three serial steps with proper mixing between them, and the intermediate concentrations should be written down rather than reconstructed later from memory.