The accuracy of GNSS-R altimetry significantly depends on the knowledge of the spacecraft orbit. The GRACE-A satellite was used to assess the orbit determination errors of CYGNSS using a single-frequency code-only and GRAPHIC approach. Orbit overlap RMS values were lower using GRAPHIC than code-only for both GRACE and CYGNSS indicating a more precise orbit solution. With GRACE, the orbit errors for GRAPHIC were smaller for all three components, radial, cross-track, and in-track. Based on the GRACE error analysis, we conclude that the 1sigma CYGNSS GRAPHIC orbit accuracy is 3 – 5 cm for radial, 5 – 10 cm for cross-track, and 10 – 15 cm for in-track placing the 3-D accuracy between 12 – 20 cm.