Beer Lambert Concentration
Calculator
Results
- Concentration (µmol/L)
- 72.347266
- Concentration (mmol/L)
- 0.072347
- Concentration (nmol/L)
- 72,347.266881
Biology and lab results
| Concentration (µmol/L) | 72.347266 |
| Concentration (mmol/L) | 0.072347 |
| Concentration (nmol/L) | 72,347.266881 |
formula-map diagram
- Concentration (µmol/L)
- 72.347266
- Concentration (mmol/L)
- 0.072347
- Concentration (nmol/L)
- 72,347.266881
Formula breakdown
Formula
c = A ÷ (ε × l)= 72.347266881029
Note
Simplified model: these results use standard textbook laboratory relationships and average constants (A260 = 1 for 50 µg/mL dsDNA, 617.96 g/mol per base pair, ~110 Da per amino acid, ideal exponential growth). Real samples vary with purity, contaminants, buffer, temperature and instrument calibration. Always confirm against your own standards and protocol; do not use for diagnostic or safety-critical work.
More in Biology and lab
See all →Frequently asked questions
What is the Beer-Lambert law and what does each term mean?+
It states that absorbance A equals the molar extinction coefficient (ε) times the path length (l) times the concentration (c): A = εlc. Absorbance is unitless, ε has units of M⁻¹cm⁻¹, path length is usually in centimeters, and concentration comes out in molar.
How do I solve for concentration using this calculator?+
Rearranging the law gives c = A / (ε x l), so you enter the measured absorbance, the known extinction coefficient for your compound at that wavelength, and the cuvette path length, and the calculator returns the concentration.
Why does the path length matter, and can I skip it?+
Path length is not something you can ignore because doubling it doubles the absorbance for the same concentration; standard cuvettes are 1 cm, which simplifies the formula but must still be entered correctly if you are using a different cuvette size, such as a microvolume 0.1 cm path.
Why is my measured absorbance not proportional to concentration at high values?+
The Beer-Lambert law is only linear over a limited absorbance range, typically up to about 1.0 to 2.0 absorbance units; at higher concentrations, stray light and molecular interactions cause deviations, so samples reading above this range should be diluted before measurement.
Where do I find the extinction coefficient for my compound?+
It is specific to each compound and wavelength, and is usually found in the literature, a reagent's certificate of analysis, or calculated from the compound's known molar absorptivity spectrum; using the wrong wavelength's coefficient is a common source of error.