How this instrument works
Mashed potatoes are one of the easiest side dishes to badly under- or over-buy for, because the useful unit — raw pounds at the store — isn't the unit anyone actually eats. A widely repeated kitchen planning convention closes that gap: about 1/2 lb of raw potatoes per person for a standard, hearty side dish serving, or closer to 1/3 lb per person for a lighter portion when there are several other sides on the table.
This instrument multiplies your guest count by the per-person rate for the serving style you pick, then converts that raw weight into an approximate cups-of-mashed-potatoes figure using another standard conversion: roughly 1 lb of raw potatoes yields about 2 cups once peeled, boiled, and mashed, since the potato loses some volume to peel and gains moisture from butter, milk, and mashing.
Both figures are planning conventions, not fixed facts — actual potato size, how much butter and milk get mashed in, and how big a scoop counts as 'a serving' at your table all shift the real numbers. Treat this as a solid starting shopping list, then round up if this is the only starch on the table or your crowd tends to go back for seconds.
- Enter the Number of guests you're serving mashed potatoes to.
- Select the Serving style — a light side (1/3 lb per person) or a standard, heartier Thanksgiving-style side (1/2 lb per person).
- Read Raw potatoes needed (lb) — how much to buy at the store before peeling and cooking.
- Read Approx. cups of mashed potatoes for a rough sense of the finished, mashed volume you'll end up serving from.
Worked example — 8 guests, standard side-dish portions
A dinner for 8 guests is serving mashed potatoes as a standard side alongside a few other dishes. At the standard 0.5 lb-per-person rate: potatoesLb = 8 × 0.5 = 4 lb of raw potatoes to buy.
Converting that raw weight to a finished estimate: cupsMashed = 4 × 2 = 8 cups of mashed potatoes once peeled, boiled, and mashed — enough for roughly a generous 1-cup serving per guest, which lines up with a typical plate's worth of mashed potatoes at a sit-down dinner.
Questions
How many pounds of potatoes do I need per person for mashed potatoes?
About 1/2 lb of raw potatoes per person is a widely repeated standard for a hearty side dish, or closer to 1/3 lb per person for a lighter portion when there are several other sides sharing the plate. These are planning conventions rather than fixed rules — appetite, the number of other dishes, and whether leftovers matter to you can all justify buying more or less.
How many cups of mashed potatoes does 1 lb of raw potatoes make?
Roughly 2 cups once peeled, boiled, and mashed — a standard, widely cited kitchen conversion. The exact yield shifts a bit with how much peel is trimmed off, how much butter and milk get mixed in, and how firmly the potatoes are mashed versus whipped light and fluffy, but 2 cups per raw pound is a reliable planning estimate.
Should I buy more potatoes if mashed potatoes are the only starch?
Yes, generally — if mashed potatoes are the sole starch on the table rather than one of several sides, guests will naturally take larger portions, so leaning toward the higher 1/2 lb-per-person rate (or even a bit above it) is a safer bet than the lighter 1/3 lb rate meant for a crowded table of sides.
What kind of potatoes work best for mashing?
Starchy or all-purpose varieties — russets and Yukon Golds are the most commonly recommended — mash up smoother and fluffier than waxy varieties like red potatoes, which hold their shape and can turn gluey when mashed. This calculator's ratios apply to potato weight generally, but the variety you choose does affect the final texture.
Does this account for leftovers?
Not by default — the standard rates here are calibrated to a generous single serving per guest at the meal itself. If you want leftovers for the next day, add roughly an extra 1/4 lb per person on top of the calculator's estimate, or simply round the guest count up when entering it here.