How Much Mashed Potatoes Per Person Calculator

Work out how many potatoes to buy and how much mashed potato to make for your headcount, based on standard per-person serving sizes.

Quick Facts

Method
Per-person serving weight × headcount, plus a leftovers buffer
Standard catering rule of thumb: about 1/2 lb (8 oz) of raw potato per person for a side dish.

Your Results

Calculated
Raw potatoes needed
-
Buy at least this much, unpeeled
Total mashed potato
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Approximate finished volume
Butter to add
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At 1 tbsp butter per person
Milk/cream to add
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At 2 tbsp per person

Ready

Enter your headcount and hit Calculate.

How much mashed potato do you need per person?

The most-cited catering rule of thumb is about 6-8 oz (170-227g) of raw, unpeeled potato per person when mashed potatoes are a side dish. That yields roughly 1/2 to 2/3 cup of finished mashed potato per serving. If potatoes are the main event of the meal (a "mash bar," a potato-focused holiday plate, or a kid-friendly dinner), bump that up to 8-10 oz per person. This calculator multiplies your chosen per-person amount by your headcount, then adds a leftovers buffer so you're not caught short.

The formula behind the numbers

Total raw potato (oz) = number of people × serving size per person (oz) × (1 + leftover % ÷ 100). That total is then converted to pounds and kilograms, and to a finished mashed-potato volume using the standard kitchen conversion of about 2 cups of mashed potato per pound of raw potato — peeling loss (typically 15-20% of raw weight) is roughly offset by the water potatoes absorb while boiling and the butter and milk stirred in afterward.

Butter and milk ratios

For a classic, creamy (not gluey) mash, a good starting ratio is about 1 tablespoon of butter and 2 tablespoons of milk or cream per person. Richer restaurant-style recipes can double the butter; lighter versions swap in more milk or a splash of the potato cooking water instead of cream.

Typical reference points

  • Thanksgiving/holiday dinner (8 people, standard side, 20% extra for leftovers): about 3.6 lb (1.6 kg) raw potatoes, roughly 7 cups of mashed potato.
  • Small weeknight dinner (4 people, light side): about 1-1.5 lb raw potatoes is plenty.
  • Large gathering (20 people, standard side, 20% extra): about 9 lb raw potatoes, roughly 18 cups of mashed potato — plan for a large pot and a sturdy masher or ricer.

Frequently Asked Questions

How much mashed potato is one serving?
A standard side-dish serving is about 1/2 to 2/3 cup (roughly 120-150g) of finished mashed potato, made from about 6-8 oz (170-227g) of raw, unpeeled potato. Adjust up for big appetites, holiday meals, or when mashed potatoes are the main dish rather than a side.
How many pounds of potatoes do I need for a crowd?
Using the 1/2 lb (8 oz) per-person rule of thumb, 2 lb of potatoes serves about 4 people, 5 lb serves about 10 people, and 10 lb serves about 20 people — all as a side dish. Add 15-20% more if you want leftovers for the next day.
Why does 1 pound of potatoes make about 2 cups of mash?
Raw potatoes lose roughly 15-20% of their weight when peeled, but they absorb water during boiling and gain volume back from added butter and milk. In practice, these effects roughly cancel out, so "1 lb raw potato in, ~2 cups mashed potato out" is a reliable kitchen shortcut even though it isn't an exact physical law.
Does the type of potato change how much I need?
Not the weight-per-person rule, but it does change texture and yield. Starchy potatoes (Russet, Idaho) mash up fluffier and absorb butter and milk well; waxy potatoes (red, new potatoes) hold more water and make a denser, creamier mash. Yukon Golds are a common middle-ground choice for mashed potatoes.

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