How many tables do you actually need?

Divide your guest count by the seats per table and round up. That is the whole calculation, and it is right about half the time.

Start with the table, not the total

A 60-inch round seats eight comfortably and ten if nobody minds touching elbows. A 72-inch round seats ten comfortably and twelve at a push. Long banquet tables run about one guest per two feet of edge, both sides: an eight-foot trestle takes eight, not six, as long as nobody is seated at the ends.

So 120 guests is fifteen tables at eight per table, or twelve at ten per table. Both are correct. They are also very different rooms.

The number the venue actually cares about

Every round table needs a clear ring around it for chairs and for people to walk behind those chairs. Budget five feet from table edge to table edge. A 60-inch round therefore occupies a circle about ten feet across once it is in use, which is roughly 78 square feet per table, not the 20 square feet the tabletop covers.

Fifteen of those is 1,170 square feet of dining alone, before the dance floor, the bar, the cake table, the DJ, or the path from the door to a seat. A venue advertising "seats 150" is quoting the tightest legal configuration, not the one you want.

Where the count goes wrong

• Counting the couple twice. You are guests at your own wedding, and a sweetheart table is still a table.
• Forgetting the vendor meals. Photographers, the band, the planner. They eat, usually at a table you did not plan.
• Assuming the head table scales. It does not. A head table of ten seats ten from one side only, so it eats twice the edge length of a regular table.
• Treating children as half a person. They take a full seat and a full place setting. What they do not take is a full meal, which is a catering line item, not a seating one.

What follows from the number

Once you know the table count, four other numbers fall out of it: linens (one per table plus two spares, because something gets spilled on before the first course), centerpieces (one per table, and the head table usually wants something different), place settings, and the floor area above.

That chain is exactly what the table calculator runs: you give it a guest count and a table size, it gives you the tables, the linens, the centerpieces and the square footage, and tells you whether your room can hold it.

When you are ready to decide who sits at those tables rather than how many there are, the seating chart maker picks up from there.