Sandwiches are ubiquitous food items and yet little is known about their environmental impacts. This paper focused on their impact on climate change and estimated the carbon footprint of commercial and home-made sandwiches. The study also explored how the information on the carbon footprint could be combined with nutritional data to assist consumers in making more informed food choices. In total, 40 different recipes were considered, focusing on most popular consumer choices in the UK. The estimated impact from ready-made sandwiches ranges from 739 g CO 2 eq. for egg & cress to 1441 g CO 2 eq. for the bacon, sausage & egg option. The carbon footprint of the most popular home-made sandwich (ham & cheese) varies from 399–843 g CO 2 eq. per sandwich, depending on the recipe. The average impact from the home-made option is around two times lower than the impact from the ready-made equivalent with the same ingredients. The greatest contributor to the carbon footprint of both types of sandwich is the agricultural production of ingredients; for ready-made sandwiches, the preparation and retail stages are also significant. Various improvement options were considered through 22 scenarios, including changes in the cultivation of ingredients, recipe changes, reduction of food waste, alternative packaging and different waste management options. The findings suggest that reductions in the carbon footprint of up to 50% are possible for ready-made sandwiches. The greatest improvement opportunities lie in reducing post-consumer waste; however, these are most difficult to realise as they involve changing consumer behaviour.