Yes, reusable coffee cups are better for the environment than single-use coffee cups. However, a reusable cup needs to be used between 20 and 100 times in order to have lower emissions than a disposable cup.

To truly achieve an environmental benefit over a disposable paper or styrofoam cup, a reusable cup must be used dozens or even hundreds of times, depending on the material. Manufacturing a durable cup made of glass, ceramic, or stainless steel requires significantly more energy and raw materials than a single thin paper cup. A standard Life Cycle Analysis (LCA) suggests that a plastic reusable cup may need to be used around 20 to 30 times to "break even" with the environmental impact of disposables, whereas a ceramic mug might require 40 to 100 uses. For a high-quality vacuum-insulated stainless steel flask, the number can be as high as 100 to 1,000 uses to offset the carbon footprint of its production and the hot water used to wash it daily. The environmental advantage of a reusable cup only manifests when it becomes a long-term habit; if a reusable cup is bought and only used a handful of times before being discarded, it is actually more harmful to the environment than the disposable alternative it was meant to replace.