The holiday table often features any number of mashed vegetable dishes, from potatoes to butternut squash to sweet potatoes and even cauliflower. But planning your shopping to get the right amount of mash can be tricky. By sight alone, it’s hard to know just how many sweet potatoes or parsnips will be enough to feed everyone. So we aimed to take the guesswork out of the process.

We tested the vegetables most commonly mashed: butternut squash, carrots, cauliflower, celery root, parsnips, Yukon Gold potatoes and sweet potatoes. We started by weighing the vegetables in bulk (just as one would when shopping at the grocery store). We then prepped them and boiled them in plain water until completely soft. From there, we drained them, mashed them and measured their final mashed volume.

As the chart below shows, the vegetables differed—sometimes by a lot—in their mashed output. The chart makes it easy to shop for just the amount needed to serve your meal. But if you want a shortcut and don’t mind potentially having a little extra, we also found that regardless of the vegetable, 3 pounds reliably produced enough for at least eight ½-cup servings.