Visual Butter Conversion Guide: Exactly How Much Is 3/4 Stick of Butter in Cups?
Butter expands when heated and condenses when chilled. Which state your butter is in dictates the most accurate measuring practice:
Cold butter straight from the refrigerator should never be jammed into measuring cups. It will create uneven voids, leaving you with less butter than intended. Cut cold butter by stick length or weigh it on a digital scale.
Softened butter at room temperature (65°F, 68°F / 18°C, 20°C) compresses smoothly into a dry measuring cup. Use a silicone spatula to pack the fat into the cup, then scrape the top flat with a bench knife.
Melted butter behaves as a true fluid. When recipes call for "3/4 stick of butter, melted," measure the solid portion first (6 tablespoons), then melt it in a saucepan or microwave. If a recipe specifies "3/8 cup of melted butter," melt a slightly larger chunk first, then pour exactly 3 fluid ounces into your liquid measuring cup. Butter loses a small fraction of water through steam during melting, altering volume if boiled aggressively.