Grain-based products, particularly whole grains, are integral to a healthy and sustainable diet. However, their nutritional quality and environmental impact vary, necessitating consideration of both aspects in sustainability assessments. This study aimed to identify nutritional indicators for grain-based foods and evaluate their suitability as functional units for carbon footprint analysis of Swedish products. Six indicators—CFQS-5, Keyhole, NRF11.3, NR-FI<inf>carb</inf>, Nutri-Score, and Nutri-Score<inf>wholegrain</inf>—were applied to 356 foods. Nutri-Score classified the highest proportion of products as high-quality (40 %), while Keyhole classified the fewest (13 %). Correlation with wholegrain content was strongest for CFQS-5 and weakest for Nutri-Score<inf>wholegrain</inf>. NRF11.3 and NR-FIcarb emerged as the most suitable functional units for carbon footprint calculations, showing moderate, statistically significant positive correlations with wholegrain content (ρ = 0.452 for NRF11.3, ρ = 0.475 for NR-FIcarb, both p < 0.001) and effectively rating grain-food categories in line with dietary guidelines. Transitioning from a weight-based to a nutrition-based functional unit, expressed as either NRF11.3 or NR-FIcarb, did not alter the finding that rice and sweet bakery products had the highest greenhouse gas emissions. However, it highlighted the favorable nutritional quality of “hard bread and crusts” and “flour, cereals, grains, and crushed cereals,” leading to reduced carbon footprints. These findings demonstrate that NRF11.3 and NR-FIcarb are equally effective in assessing the quality of grain-based foods and can be applied in food life cycle assessments, providing a practical tool for identifying foods with lower climate impact and higher nutritional value