How to size a seafood boil so nobody walks away hungry
Why portions vary
The same group of four can need anywhere from 1.2kg to 2.8kg of whole shellfish depending on how much shell ends up in the bin, how much beer ends up in the glass, and whether you're feeding people who treat prawns like popcorn. Whole crab is roughly 40% meat by weight once the shell goes. Prawns are about 50%. Mussels are about 30%. That swing alone moves the math by half a kilo for a small group, so the rule we land on is 500g of whole shellfish per adult with sides, or 700g per adult without.
That number bakes in a 10 to 15% buffer. We'd rather you have leftovers than have a quiet uncle pretending he's full. If you want to dial it tighter, our functions team calculates per head off the actual menu mix you pick.
Seafood-only vs mixed bag
A mixed bag (prawn, mussel, corn, potato, sausage) needs less protein per person because the corn and potato carry the meal. We size mixed bags at 250g of seafood plus 250g of sides per adult. That's where the standard 500g number comes from.
If you're going seafood-only (straight crab, straight lobster, straight prawn), bump the seafood allocation to 700g per adult. People eat more when there's less filler to slow them down. For a deeper read on which protein actually goes furthest, snow vs king crab covers the price-to-meat ratios.
How we calculate at Kickin'Inn
Every Kickin'Inn bag is portioned by weight before it goes near the broth. A standard Mixed Bag holds 280g of seafood (prawn + mussel) plus 220g of corn + potato. A Family Value Pack holds the same per-head ratio across three to four servings. For functions, we scale the same ratio per confirmed head. There is no estimating once your booking is locked.
The reason the bag format works for portions: every diner gets their own sealed allocation, so there's no fighting over the last claw and no awkward "did everyone get enough?" moment halfway through the meal. The math is done in the kitchen, not at the table.
Group factors that change everything
Three things move the per-head number more than the seafood type. First, drinks. Heavy drinkers eat less seafood by about 20% (they fill on the beer). Second, age mix. A table of 20-somethings demolishes 30% more than a table of grandparents. Third, time of day. Lunch boils run lighter than dinner boils because people are pacing themselves for the rest of the day.
If you're hosting a known-hungry crowd (work do, footy mates, post-event crew), add 20% to whatever the calculator returns. The seafood boil party guide has the full host-side playbook.
Kids and big eaters
Count kids under 8 as half a person. Kids 8 to 12 as 0.75. Teenage boys as 1.5 (we are not joking). If you'd rather just round up and accept the leftovers, that works too. Cold leftover seafood reheated in butter the next day is one of the better lunches you'll have.
Known big eaters: bump them to 700g per head and order them their own Mixed Bag. Nobody wants to be the one watching the prawns disappear from the shared plate.
When to add extra
Add a 20% buffer when: you're feeding 8+ guests (variance compounds), you've got a known seafood lover at the table, you've skipped a course (no entrees = bigger main), or it's a celebration. Birthday boils run hotter than weekday boils. If you're booking a birthday, join the Birthday Club. The birthday person eats free, so you're effectively pre-loaded with extra budget.
For 9+ guests, stop calculating on the bag level and start booking on the function level. The functions team handles the spice levels, dietaries, drink runs and the per-head quote as a single brief, usually faster than you can build a calculator estimate.
