Convert UV absorbance into transmission values for labs. See decimal, percent, and absorbance reversals together. Helpful for checks, reports, calibration, and classroom spectroscopy practice.
Absorbance to decimal transmittance: T = 10-A
Absorbance to percent transmittance: %T = 100 × 10-A
Decimal transmittance to absorbance: A = -log10(T)
Percent transmittance to absorbance: A = -log10(%T / 100)
A is absorbance. T is decimal transmittance. %T is percent transmittance. The calculator returns all related values from the selected input mode.
| Sample | Wavelength (nm) | Absorbance (A) | Decimal T | %T |
|---|---|---|---|---|
| Blank Check | 254 | 0.100 | 0.794328 | 79.432823 |
| Reference Mix | 280 | 0.500 | 0.316228 | 31.622777 |
| Unknown A | 320 | 1.000 | 0.100000 | 10.000000 |
| Unknown B | 365 | 1.500 | 0.031623 | 3.162278 |
A UV absorbance to transmittance calculator helps convert one spectroscopy reading into another useful format. Many chemistry workflows record absorbance first. Some reports, instruments, and validation sheets also need transmittance values. This calculator gives decimal transmittance, percent transmittance, and reverse absorbance checks in one place. It works well for teaching, routine bench work, method review, and fast data confirmation before reporting.
Absorbance and transmittance describe the same light event from different angles. Absorbance shows how strongly a sample reduces light intensity. Transmittance shows how much light passes through the sample. UV spectroscopy often uses absorbance because it scales well for comparison. Percent transmittance is still common in instrument displays, older procedures, and audit documents. Converting between them helps keep records consistent and easier to interpret.
This calculator is useful during standard preparation, sample screening, and instrument performance checks. It can support laboratory training because students often need to see how a small absorbance shift changes percent transmittance. It also helps with calibration review. A sample with higher absorbance will always show lower transmittance. That relationship is not linear. Because of that, quick manual estimates can be misleading. A calculator removes that guesswork.
Fast conversion improves documentation quality. It also reduces transcription mistakes when moving values into notebooks, spreadsheets, or quality records. Adding wavelength, path length, and temperature gives more context to each entry. Those extra details do not change the absorbance to transmittance equation when absorbance is already measured, but they can help track test conditions. Use this tool when you need reliable UV conversion results, clearer reports, and better spectroscopy decisions with less manual effort.
It converts UV absorbance into decimal transmittance and percent transmittance. It also supports reverse conversion from decimal or percent transmittance back to absorbance for checking instrument data.
The main relationship is T = 10-A. After that, percent transmittance is found with %T = 100 × T. This gives both decimal and percentage outputs from one absorbance value.
Absorbance and transmittance follow a logarithmic relationship. Because of that, the response is not linear. Small absorbance differences can produce noticeable changes in transmission values.
Yes. It is useful for chemistry classes, lab training, and spectroscopy demonstrations. Students can compare absorbance, decimal transmittance, and percent transmittance in one simple workflow.
If absorbance is already measured, path length does not change the absorbance-to-transmittance conversion itself. Still, recording path length is useful for method context and data traceability.
A very low percent transmittance means the sample is absorbing most of the UV light. This often suggests strong absorption, high concentration, or a need to dilute the sample.
Yes. Negative absorbance can occur from blanking issues, drift, or reference mismatch. In those cases, calculated transmittance may appear above 100%, which signals a setup check is needed.
CSV is helpful for spreadsheet work and batch review. PDF is useful for quick sharing, print records, or attaching a simple result page to laboratory notes.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.