Family formals time math: groups per window

The formula

Family formals time is not a feeling. For a given list it is three numbers added together:

Total = gather time + (groups × minutes per group) + slack

Gather time: getting the first big group in one place. Plan 5 to 10 minutes.
Minutes per group: about 1 to 2 when the next group is ready and a helper is calling names. Without a helper, plan longer. See below.
Slack: a few minutes for the missing uncle, the child who needs a minute, the extra “one more with the cousins”. Plan 3 to 5.

These are planning numbers, not measurements. Replace them with your own after you time the next few weddings. The general method and the reasons lists run long are in How long do family formals take?. This guide is the arithmetic.

Why a caller changes minutes per group

Most of the time between two photos is not photography. It is the pause while the next set of people is found and walks into place. If a relative on the couple’s side holds a numbered list and calls the next group by name while you are still shooting the current one, that pause mostly disappears. People are already walking toward the spot when you finish. That is how a group takes 1 to 2 minutes instead of 3 to 4.

To make it work, the caller needs the list in advance, with every name written out, and needs to know the order. Appoint one for each side of the family.

Time for 10, 12 and 15 groups

With a caller, a gather time of 5 to 10 minutes, and no slack added yet:

Groups	Shooting at 1 min	Shooting at 2 min	Plus 5 to 10 gather
10	10 min	20 min	15 to 30 min
12	12 min	24 min	17 to 34 min
15	15 min	30 min	20 to 40 min

Add 3 to 5 minutes of slack and put the higher number in the timeline. A 12-group list should get a 30 to 35 minute block, not 20. If you only write the 1-minute figure you will be over every time.

How many groups fit in your window

Turn it around: subtract gather (5) and slack (3) from the window you have, then divide by minutes per group.

Window	Left for shooting	At 1 min	At 1.5 min	At 2 min
20 min	12 min	12 groups	8 groups	6 groups
30 min	22 min	22 groups	14 groups	11 groups
45 min	37 min	37 groups	24 groups	18 groups

Read the middle column honestly. In a 20-minute window, 10 groups only fit if every group takes about a minute, which needs a good caller, a compact location and guests who showed up. At the more usual 1.5 to 2 minutes, a 20-minute window holds 6 to 8 groups.

Worked example: a 12-group list in a 30-minute window

Gather: 7 minutes (the couple’s parents are close, the grandparents are seated nearby).
12 groups at 1.5 minutes: 18 minutes.
Slack: 4 minutes.

Total: 29 minutes. It fits, with one minute to spare. If the real list grows to 15 groups, the same arithmetic gives 7 + 22.5 + 4 = 33.5 minutes, so you know in advance that three extra groups need three or four extra minutes, or a move to the reception.

What to do when the number is bigger than the window

Cut or merge groups. Three small add-on groups that differ by one person can sometimes become one.
Move extended-family groups to the reception. Everyone is in the room anyway, and it costs no portrait time.
Ask for more time only if the couple would trade it against their own portraits. Show them the numbers. People decide faster when they see 36 minutes against a 20-minute block.

Put the answer on the timeline

Write the estimated total as one block with a start and end time, next to the numbered list. When the day slips, that block shows what is left to cut. If you use one of the six- or eight-hour layouts, set that block before you shift the rest around the ceremony time.

Do the math with the couple, in writing. The family formals list builder has the couple questions, a numbered list with minute estimates, and the email for when it does not fit ($14).

Fit the number into a day. The timeline presets are four 6- and 8-hour layouts with and without a first look, and rules for shifting family-formal minutes ($15).

Family formals time math: how many groups fit in your window