Non-metallic materials such as carbon have become a relevant alternative as reinforcement for concrete due to their high strength potential and their resistance against corrosion. Such materials can be used as sole reinforcing components in new structures or as strengthening materials for existing structures with steel reinforcement. Either way, a design has to be embedded into the semi-probabilistic safety concept with partial safety factors for the strength of materials. While partial safety factors for reinforcing steel and concrete are available based on extensive long-term experience, there is a lack of experience regarding the use of innovative materials such as carbon as concrete reinforcement. Thus, a theoretical safety concept is required to determine new partial safety factors. This paper develops such a concept based upon safety margins-that is, the ratio of bearing capacities derived from a full probabilistic view on the one hand and a semi-probabilistic approach as applied in practice on the other hand. For ordinary steel-reinforced concrete, this falls in a range above 1 whereby upper ranges occur with higher reinforcement ratios dominated by brittle concrete failure. This is used as reference to derive partial safety factors for carbon-a favorite non-metallic reinforcement. It is further exemplarily shown how particular carbon reinforcement design parameters influence the safety margin which might justify a more differentiated safety concept for carbon concrete.