Dietary Buffet Calculator

This calculator splits your total guest count into dietary groups based on the percentages you provide. It then calculates the food quantity needed for each group, adjusted for event duration and a variety factor.

The Calculation

• Group size = Total guests × Dietary percentage
• Food per person = Base amount × Duration factor × Variety factor
• Group food total = Group size × Adjusted food per person
• Dishes recommended = Base dishes + dietary categories

The 300 g base amount

The default of 300 g per person reflects UK finger-buffet guidance of roughly 250 g of savoury food plus around 50 g of something sweet — about ½ to 1 lb (227-454 g) per head when the buffet is the main offering. Lower the base if you are also serving a sit-down meal, or raise it for a hungry, meal-replacing spread. This is a planning estimate, not a fixed standard.

The duration factor

The base amount is calibrated to a 2-hour event. Guests graze more the longer they stay, so we adjust by about ±15% per hour around that 2-hour baseline: a 3-hour event uses ×1.15 (15% more), a 4-hour event ×1.30, and a 1-hour reception ×0.85 (15% less). It is a rough heuristic to scale grazing with time, not a sourced rule.

The variety factor

The default variety factor of 1.15 adds a 15% buffer over the mathematical minimum, in line with common catering advice to over-cater by 10-15% so no single popular dish runs out early. Adjust it in Advanced Options if you want a tighter or more generous margin.