The fuller answer
Why these portion sizes
Biryani is denser and more filling than people expect. The single biggest mistake first-time party orderers make is overordering — buying 1.5 pounds per head because the menu lists it by the pound. Three-quarters of a pound per adult is the calibrated number from twelve months of Chantilly catering orders. It leaves a small buffer for second helpings without producing a fridge of leftovers. For kids under 12, half a pound is the realistic number — even biryani-loving kids rarely finish more.
10-person band (small family gathering)
For 10 adults, order 7 to 8 pounds of biryani when biryani is the only main. That is two full party trays. For mixed protein, split 60/40 chicken to goat — chicken is the safe default for newcomers and kids, goat is the showpiece for regulars. Add one quart of mirchi ka salan, one quart of raita, 20 boiled eggs, and ten pieces of gulab jamun. Twenty-four hours notice is comfortable; twelve hours is possible.
25-person band (medium party)
For 25 adults, order 18 to 20 pounds of biryani — typically three large trays. Split 55% chicken biryani, 35% goat biryani, 10% vegetable biryani to cover vegetarians. Add three quarts of mirchi ka salan, three quarts of raita, two dozen boiled eggs, an appetizer platter of samosas and paneer tikka, a naan basket, and 25 pieces of gulab jamun. Forty-eight hours notice is comfortable. Drop-off setup with chafing dishes and sterno burners is included.
50-person band (large party / corporate event)
For 50 adults, order 35 to 40 pounds of biryani across five to six full trays. Split 50% chicken, 30% goat, 20% vegetable. Add six quarts of mirchi ka salan, six quarts of raita, four dozen boiled eggs, a 50-piece appetizer platter, two naan baskets, a tray of butter chicken or paneer butter masala for variety, and 50 pieces of gulab jamun. Seventy-two hours notice is the minimum; one week is comfortable. Halal-certified meat on request.
Kids, vegetarians, and dietary edge cases
Kids under 12 eat about half a pound — count them at half-adult rate when sizing the order. Vegetarians should get vegetable biryani (or a non-biryani vegetarian curry like paneer butter masala) at the same per-adult portion. For mixed-diet families, add a 60/40 vegetable to non-veg ratio above your headcount-derived total so vegetarians have full coverage. Heat-sensitive guests do better with mild (1/5) — order a separate pot if half the table needs mild and half wants default heat.
Lead time and pickup logistics
Under 4 pounds: 2 to 4 hours notice on weekdays. 4 to 10 pounds: 24 hours comfortable, 12 hours possible. 10 to 25 pounds: 48 hours. 25 plus pounds: 72 hours minimum, one week comfortable for weekend catering. Festival weeks (Diwali, Eid, Holi) double the lead time. Biryani holds heat in sealed pots for 30 to 45 minutes after pickup. Past 90 minutes, transfer to a covered oven-safe dish at 200°F or rewarm at 300°F with foil and a tablespoon of water.