Choose capacity, table count, or required size
Use one clear goal at a time. Capacity mode determines whole seats at one existing table. Tables-needed mode divides a guest target by that capacity and rounds upward. Size mode works backward from target seats to a minimum rectangular length or round radius.
Model rectangular long sides and optional head seats
Whole seats along both long sides equal two times the floor of table length divided by personal edge space. Optional head seating adds one person at each end. For a required size, remaining seats after head seats are split between the long sides and rounded upward.
Use circumference for round-table seating
Round capacity is the floor of circumference divided by personal edge space, where circumference is two times pi times radius. Required radius reverses that relationship without rounding the geometric value.
Reproduce the published seating examples
A 150-centimeter-radius round table with 70 centimeters per person seats 13 whole people, so 200 guests require 16 tables. For eight rectangular seats at 60 centimeters per person, required length is 240 centimeters without head seats or 180 centimeters with two head seats.
Verify the physical room layout
Edge length alone does not prove a workable event plan. Chair width, armrests, table legs and bases, place settings, centerpieces, aisles, servers, wheelchair access, exits, local occupancy rules, venue inventory, and mixed table sizes can reduce usable capacity.