How to use (3 steps)
- Pick the mode: simple A = ε·l·c or the calibration curve regression.
- Fill the known values. Choose one unknown in the simple mode, or enter 2+ standards for the calibration.
- Tap Compute to see the solved value, transmittance, regression line, residuals, and steps. Copy URL shares the exact setup.
The example is preloaded and calculated automatically so you can see the output at a glance.
Inputs
Keep units consistent so A = ε·l·c holds. The unknown field is disabled because it is solved automatically.
Standard solutions (concentration and absorbance)
| Standard # | Concentration | Absorbance | Remove |
|---|---|---|---|
| 1 | |||
| 2 | |||
| 3 | |||
| 4 | |||
| 5 |
Results
How it is calculated
FAQ
Which units should I use?
Use any consistent units so that A = ε·l·c is valid. A typical set is ε in L·mol⁻¹·cm⁻¹, l in cm, and c in mol/L. This calculator does not convert units automatically.
How many standard solutions are enough?
Two points define a line, but to average out noise you usually measure 4-6 standards. Check R^2 and the residuals to ensure no outliers dominate the fit.
When should I force the line through the origin?
Ideally A is zero when c is zero, so the line crosses the origin. Instrument offsets or blanks can shift the intercept, so compare both models to see which matches your data better.
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