estimating mashed potato

A question about : estimating mashed potato

I am sure that there are some OS people here who know!

Community get-together this evening - I have been given a large dish (about 30cms square & 15 deep) to slightly over-fill with mashed potato (ooh, we know how to do Valentines!).
I am thinking that I will peel & quarter enough potatoes to fill this dish one-&-a-half times and that will give me the right amount.

I think that it is to feed about 25 people, so I'll double check on numbers of potatoes as I go.

I don't think that the organiser has much of a clue!

Anyone got any other thoughts about estimating the correct quantity?

Many thanks!

Best answers:

• This is a very rough estimate, but I would boil 3 supermarket bags of potatoes to fill a dish that size.
  Hth
  Polly
  Have a lovely evening.
• As suggested by polly, for 25 people I'd probably do about 3kilos of potatoes.
  I wouldn't do three bags full, but thats because I tend to buy the 2.5 kilo bags...
• I'd over estimate rather than under estimate. If you do too much you can always freeze the left over mash for another time. I freeze individual portions in bags and find it really useful if I am just wanting to plate a meal up for one.
  Have a good night!
• Dunno whether this would be relevant to a catering situation, but when I'm cooking at home I allow 200g raw, unpeeled, potatoes per person for a good sized portion if the mash is a main part of the meal (eg for sausage & mash), or 100-150g for a small to medium portion if it's not and this seems to work quite well.
• Same here, 200g per person. gives a good portion of mash
• I'd definitely over estimate. I love LO fried mash with a cooked breakfast or cold meat.
• +1 to overcater the amounts wildly. Not only do you then have the extra spud for other occasions but also a running start on champ/colcannon, topping cottage pie & even potato cakes.
  Have fun!
• Boil/mash some, but if you're unsure then bake a whole load and leave them as baked and if you start to run out you can cut those open, scoop them out and mash them ... and if they're not needed you can just freeze them as spuds ready to be nuked.
• You could easily turn any leftovers into Cheesy Leftover Mashed Potato Muffins from Just a Taste.
  hth
• Thanks so much all!
  I did do about 200g per person, so about 5kg., mashed with 125g butter & 450ml milk. I took out a little for frying up for breakfast, and the rest just filled the tin. I didn't know exactly how it went, as 4 of us were feeding 100, but it seemed about right, and now I know!