pmol/L to pg/mL Converter
pmol/L to pg/mL Conversion Chart (per 1 pmol/L)
| Molecule | MW (g/mol) | 1 pmol/L equals |
|---|---|---|
| Estradiol (E2) | 272.38 | 0.2724 pg/mL |
| Progesterone | 314.47 | 0.3145 pg/mL |
| Testosterone | 288.42 | 0.2884 pg/mL |
| Cortisol | 362.46 | 0.3625 pg/mL |
| Free T3 | 650.97 | 0.6510 pg/mL |
| Free T4 | 776.87 | 0.7769 pg/mL |
| PTH | 9500 | 9.5 pg/mL |
| Insulin | 5808 | 5.808 pg/mL |
| Vitamin B12 | 1355.37 | 1.3554 pg/mL |
| Folate | 441.4 | 0.4414 pg/mL |
pmol/L is a molar concentration (a count of molecules) while pg/mL is a mass concentration, so the molecular weight of the chosen substance is required to convert between them — larger molecules produce a larger pg/mL value for the same pmol/L. Estradiol is one of the most common searches for this conversion since many labs report it in pmol/L while many US reference ranges use pg/mL. For anything not listed, use the Custom molecular weight option and confirm against a published reference.
Popular pmol/L to pg/mL Conversions
pmol/L to pg/mL: Why There’s No Single Number to Memorize
If you searched “pmol/L to pg/mL” hoping for one clean multiplier the way ng/mL to ppm gave you one, here’s the catch: there isn’t one. Type that exact phrase into a search engine and you’ll find factors that flatly contradict each other. One page says multiply by 0.27, another says 1.36, and a third says 0.65. None of them are wrong. They’re simply answering the question for completely different substances, and the page often doesn’t make that obvious until several paragraphs later.
Is There One Conversion Factor for pmol/L to pg/mL?
No, and this is the single most important thing to understand before you convert anything.
pmol/L counts molecules.
pg/mL measures their weight.
The bridge between a molecule count and a weight is the molecule’s molecular weight, and molecular weight is different for every substance—sometimes dramatically different.
Estradiol and Vitamin B12 are both commonly reported in these units, but their molecular weights are nowhere close to each other. As a result, their conversion factors aren’t close either.
Why the Same Two Units Convert Differently for Every Hormone
A picomole of a small, light molecule weighs very little.
A picomole of a large, heavy molecule weighs much more, even though it’s still exactly one picomole of material.
Vitamin B12 (Cobalamin) has a molecular weight of approximately 1,355 g/mol, making it a relatively heavy molecule.
Estradiol has a molecular weight of only 272 g/mol.
Convert the same pmol/L value for both substances and Vitamin B12 will produce a pg/mL value roughly five times larger than estradiol.
Nothing is wrong with the math—that difference simply reflects the size of the molecules.
The Actual Formula
pg/mL = pmol/L × molecular weight (g/mol) ÷ 1000
Reverse conversion:
pmol/L = pg/mL × 1000 ÷ molecular weight (g/mol)
The molecular weight is doing all the work in these formulas.
Use the correct molecular weight for your specific substance and the calculation is straightforward.
Use the wrong molecular weight—even one that seems reasonable—and you’ll get a precise but completely incorrect result.
Estradiol: 367 pmol/L to pg/mL
Estradiol molecular weight = 272.38 g/mol
367 × 272.38 ÷ 1000 = 99.98 pg/mL
Vitamin B12: 300 pmol/L to pg/mL
Vitamin B12 molecular weight = 1,355.4 g/mol
300 × 1355.4 ÷ 1000 = 406.6 pg/mL
Free T3: 6 pmol/L to pg/mL
Free T3 molecular weight = 650.98 g/mol
6 × 650.98 ÷ 1000 = 3.9 pg/mL
Notice how differently similar input values produce different results. The molecular weight—not the calculation—is responsible for the difference.
What Happens If You Use the Wrong Factor
Imagine you’re converting a Vitamin B12 result but accidentally use an estradiol conversion factor because a website doesn’t clearly identify which substance the factor belongs to.
Using 300 pmol/L:
- Correct Vitamin B12 conversion: 406.6 pg/mL
- Incorrect estradiol conversion: about 82 pg/mL
That’s not a small rounding error.
It’s approximately a five-fold difference, potentially making a normal result appear severely deficient.
Always verify that the molecular weight belongs to the exact substance shown on your laboratory report.
Common Substances and Their Conversion Factors
| Substance | Molecular Weight (g/mol) | Multiply pmol/L by |
|---|---|---|
| Estradiol (E2) | 272.38 | 0.272 |
| Vitamin B12 (Cobalamin) | 1355.4 | 1.355 |
| Free T3 | 650.98 | 0.651 |
| Free T4 | 776.87 | 0.777 |
| Progesterone | 314.46 | 0.314 |
| Testosterone | 288.42 | 0.288 |
A Word on Reference Ranges
After converting your value correctly, compare it with the reference range printed on your own laboratory report rather than a generic chart.
Reference ranges can vary depending on:
- Sex
- Edad
- Menstrual cycle phase
- Pregnancy status
- Laboratory assay
- Reporting units
The Short Version
There is no universal pmol/L to pg/mL conversion factor.
The correct calculation always depends on the molecular weight of the substance being measured.
Use this formula:
pg/mL = pmol/L × molecular weight (g/mol) ÷ 1000
Whether you’re converting estradiol, Vitamin B12, Free T3, Free T4, testosterone, progesterone, or another substance, the molecular weight determines the correct answer.
Rather than looking up molecular weights manually every time, our pmol/L to pg/mL Converter includes the correct conversion factors for estradiol, Vitamin B12, Free T3, Free T4, and other common laboratory substances, helping you avoid costly conversion mistakes.