How much Ground cinnamon equals one eighth teaspoon of cinnamon oil?

To substitute ground cinnamon for cinnamon oil, a general rule of thumb is to use 1 teaspoon of ground cinnamon for every 1/8 teaspoon of cinnamon oil. Therefore, you would need 1 teaspoon of ground cinnamon to equal 1/8 teaspoon of cinnamon oil. Adjustments may be necessary based on personal taste, as the flavor concentration can vary.