Why do fewer people show up than said yes?

Because a yes is a prediction, not a commitment. The longer the gap between the reply and the event, the more life happens in between — illness, work, weather, childcare and competing invitations. Free events lose more guests than paid ones, because nobody forfeits anything by not turning up.

How should I plan food if I only have a yes count?

Plan food from confirmed attending guests, not from the invited list, and treat maybes as a separate number rather than half a yes. If your dish scales easily, plan slightly under the yes count and keep a buffer that keeps; if it does not scale, plan to the yes count and accept some waste.

Do reminders improve attendance?

One short reminder a day or two before helps most for events people forget rather than events people avoid — weekday sessions, free workshops, anything booked weeks earlier. It does little for events where the guest has already decided not to come.

How do I get a more accurate count?

Shorten the gap between the reply and the event, make changing an answer easy, and ask for a party size instead of just a name. Guests who can update their own reply will tell you they cannot make it; guests who would have to email the host usually just do not appear.

Should I over-invite to hit a target number?

Only when capacity is not a constraint and cost per guest is low. If you are paying per plate or the room has a legal limit, over-inviting turns a shortfall problem into a turn-people-away problem, which is worse.

Guide

How many guests will actually show up?

Every host eventually learns that a yes count and a door count are different numbers. This is how to think about the gap without pretending to know it exactly.

There is no universal drop-off percentage

You will find confident-sounding numbers online — "expect 20% to drop out" — with nothing behind them. Ignore them. The gap between yes and attended depends on your event, your guests and your lead time, and it varies far too much for a single figure to be useful. What you can do is judge which direction each factor pushes you, and plan so that being wrong by a handful of people does not break anything.

Six factors that widen or narrow the gap

Lead time
The further out a yes was given, the weaker it is. A reply from four months ago should carry less weight than one from last week.
Cost to the guest
Anything a guest paid for or committed effort to — a ticket, a gift, travel booked — makes them far likelier to appear. Free and casual means softer numbers.
Weekday and time
Weekday evenings compete with everything; weekend mornings compete with almost nothing. Same guest list, different result.
Weather and season
Outdoor events and December events both lose guests late, for opposite reasons. Have a plan that does not need the last ten people.
Ease of changing an answer
If updating a reply is easy, your count corrects itself before the day. If it means emailing the host, silence becomes the default.
Group replies
One household reply covering four people can change by four. Counting people rather than responses shows you the real exposure.

Plan so the number can move

Practical version: order what scales badly to the confirmed count, and let what scales well absorb the variance. Seating, plated meals and per-person venue fees should track confirmed attending guests. Drinks, sides, snacks and anything that keeps can flex. Keep maybes visible as their own number so you know your realistic range rather than one optimistic figure.

The fastest way to tighten the range is to make it easy for guests to change their own answer, and to set a deadline close enough to the event that plans have already settled — see RSVP deadline etiquette. To see your live attending, declined, maybe and no-reply numbers side by side, see guest list management.

Questions people ask

Why do fewer people show up than said yes?: Because a yes is a prediction, not a commitment. The longer the gap between the reply and the event, the more life happens in between — illness, work, weather, childcare and competing invitations. Free events lose more guests than paid ones, because nobody forfeits anything by not turning up.
How should I plan food if I only have a yes count?: Plan food from confirmed attending guests, not from the invited list, and treat maybes as a separate number rather than half a yes. If your dish scales easily, plan slightly under the yes count and keep a buffer that keeps; if it does not scale, plan to the yes count and accept some waste.
Do reminders improve attendance?: One short reminder a day or two before helps most for events people forget rather than events people avoid — weekday sessions, free workshops, anything booked weeks earlier. It does little for events where the guest has already decided not to come.
How do I get a more accurate count?: Shorten the gap between the reply and the event, make changing an answer easy, and ask for a party size instead of just a name. Guests who can update their own reply will tell you they cannot make it; guests who would have to email the host usually just do not appear.
Should I over-invite to hit a target number?: Only when capacity is not a constraint and cost per guest is low. If you are paying per plate or the room has a legal limit, over-inviting turns a shortfall problem into a turn-people-away problem, which is worse.

Track attending, maybe and no-reply separately

Publish your event and watch the three numbers that actually drive your order.

How many guests will actually show up?

There is no universal drop-off percentage

Six factors that widen or narrow the gap

Lead time

Cost to the guest

Weekday and time

Weather and season

Ease of changing an answer

Group replies

Plan so the number can move

Questions people ask

Track attending, maybe and no-reply separately