A highly simplified variation on the do-it-yourself spectrophotometer using a smartphone's light sensor as a detector and an app to calculate and display absorbance values was constructed and tested. This simple version requires no need for electronic components or postmeasurement spectral analysis. Calibration graphs constructed from two molecules that absorb light maximally at different wavelengths (430 and 630 nm) demonstrate linearity with R[superscript 2] values of 0.9975 and 0.9848, respectively.