What size mixer do I need?
Size a planetary mixer by your largest single batch and how stiff it is. You can't fill a bowl to the brim — light mixes (whipped cream, egg whites, thin batter) use most of the bowl, but stiff bread and pizza dough use only about half before the motor and bowl can't handle it. Estimate your biggest batch in quarts, derate for stiffness, and pick a bowl capacity above that with headroom. This tool does that; always check the model's rated dough capacity for your specific product.
How is a planetary mixer's capacity rated?
By bowl volume in quarts (common commercial sizes: 5, 8, 10, 12, 20, 30, 40, 60, 80, 140 qt). But usable capacity depends on the product: a 20 qt mixer holds far less stiff pizza dough than cake batter. Manufacturers publish a maximum dough capacity (often as an AR — absorption ratio) per model; that governs stiff mixing, not the raw bowl number.
Can I mix pizza or bread dough in any mixer?
Only up to the model's rated dough capacity. Stiff, low-hydration dough is the hardest load — overloading it burns out the transmission. A mixer rated 20 qt might handle only ~25 lb of pizza dough. For dough-heavy shops, size the bowl up and confirm the dough/AR rating, or choose a spiral mixer, which is built specifically for dough.
Planetary or spiral mixer?
A planetary mixer is the versatile choice — whips, creams, batters, and moderate dough with interchangeable beater/whip/hook. A spiral mixer is purpose-built for large volumes of bread and pizza dough: the bowl and hook turn together, developing gluten gently at high capacity with less heat. High-volume pizzerias and bakeries run spirals; most kitchens do fine with a planetary.
Is this an exact size?
No — it's a planning rule of thumb. Real capacity depends on the product, hydration, and the model's rated dough limit. Use it to shortlist, then confirm the spec sheet's maximum capacity for what you actually mix.