Buying the right amount of potatoes for mashed potatoes is one of the easiest things to get wrong when cooking for a crowd — too little and guests go without seconds, too much and you're stuck with a fridge full of leftovers. This calculator applies standard catering per-person ratios to your exact guest count so you buy the right amount the first time.
How the calculator works
The calculator multiplies your guest count by a per-person raw-potato allowance: about 0.5 lb per person when mashed potatoes are a side dish alongside other food, or about 0.75 lb per person when they're the main feature of the meal. If you want a leftover buffer, it adds 20% on top of that base amount. These ratios reflect common catering and recipe guidance for how much raw, unpeeled potato weight a typical adult eats in a mashed-potato serving.
Inputs and what they mean
Guest count is the headcount you're cooking for — the single input that scales the result most directly. Serving size tells the calculator whether potatoes are a side (lighter portion) or the main event (heavier portion). The leftovers toggle adds a flat 20% buffer for second helpings or next-day meals. None of these inputs account for exceptionally large appetites or very young children, so adjust the guest count up or down slightly if your group skews unusually hungry or light.
Limits and edge cases
This calculator estimates raw potato weight only — it doesn't account for butter, milk, cream cheese, or other mix-ins, which add volume but not potato weight. The 2-cups-per-pound mashed yield is an approximation; waxy potato varieties, heavy peeling, or very wet mashing techniques can shift the actual yield up or down. For very large events (100+ guests) or unusual dietary contexts, cross-check the result against a full catering menu plan rather than relying on this rule of thumb alone.