Research on feedback shows the dialogic perspective as one that potentially promotes learning improvement. This article presents the Dialogic Feedback Index (DFI), a measure that contributes to establishing to what extent feedback design is potentially dialogic. Performing the study in an online context enabled us to evaluate the potential of the index to measure the institutional situation in relation to dialogic feedback. The applied case allowed us to identify four teaching and learning contexts whose designs range from low to high dialogic context. We were also able to establish three components which had a great impact in differentiating one context from another. Specifically, it was found that designing teaching and learning contexts with high levels of dialogic potential of feedback involves: (1) providing feedback before the task is completed, (2) incorporating peer feedback into the process and (3) allowing resubmission once the feedback has been received. The DFI is intended as an applied tool for teaching staff and institutions. With it they can determine the level of dialogic potential of feedback and plan how to improve it.