Accurate characterization of shape, waviness, and roughness relies on traceable groove depth standards. A custom dual-wavelength Fizeau interferometer was developed to calibrate ISO 5436-1 type A1 groove material measures. Two interferometric methods were implemented: the fractional fringe method and a two-dimensional Fast Fourier Transform (FFT) phase retrieval method. A 5.75 μm nominal depth standard was measured and results were compared with stylus profilometry and a PTB reference value. Agreement within measurement uncertainties was achieved, demonstrating traceability to the SI metre and supporting the establishment of an interferometric primary standard for groove depth calibration.