Booking advice for Paris is usually one of two extremes: book everything months ahead, or just walk in. Both are wrong most of the time, and the right answer depends on three things you already know before you leave home.
The verdict
Book weeks ahead only for a small number of restaurants with more demand than seats — and only if the meal is the point of the evening.
Book the same day or the day before for almost everything else, especially dinner on a weekend.
Walk in at lunch, on weekdays, and in neighbourhoods away from the centre.
What actually decides it
The size of your group. Two people can nearly always find a table, somewhere, that evening. Six people cannot. Above four, book — the constraint is the room's layout, not its popularity.
The day and the hour. Friday and Saturday evenings are the hardest. Sunday and Monday, many kitchens are closed, which concentrates demand on those that are open. Tuesday lunch is the easiest meal of the week.
The neighbourhood. In the centre and the Marais, weekend evenings fill. Two metro stops east or south, the same evening is open.
The times that change everything
Paris eats late. Dinner service generally starts around seven or half past, and the room fills between eight thirty and nine.
Arriving at seven — you will often walk into a place that is technically full later. The room is empty and the service is unhurried.
Arriving at nine on a Saturday without a booking, in the centre — you will spend forty minutes looking.
Arriving at ten — many kitchens have stopped. This is the mistake visitors from later-eating countries make most often.
The same restaurant that is impossible at nine is available at seven. Shifting your evening by ninety minutes solves most booking problems for free.
How to book
By phone is still normal in Paris, and for smaller places it is often the only way. It also gets you a better table than a platform booking.
Booking platforms cover most restaurants and are easier from abroad. They also show availability honestly, which is useful for judging how booked a place really is.
By email or the restaurant's own site works for the places that keep some seats off the platforms.
If you do not speak French, booking online avoids the problem entirely.
When booking far ahead is genuinely necessary
A handful of restaurants in Paris open reservations one to two months ahead and fill within hours. If one of them is the reason for your trip, treat it like a flight: know the release date, be ready when it opens.
For everything else, booking two months out means committing to what you will feel like eating on a Tuesday in November. That is a worse decision than booking on the day.
Who this does not suit
If you are travelling with a group of six or more, ignore the relaxed advice above and book everything, early.
If you have dietary restrictions that need kitchen cooperation, book and mention them when you book. Not on arrival.
If the meal is the occasion — a proposal, a birthday, a once-in-a-trip dinner — book ahead and accept the constraint. Certainty is what you are buying.
What we do not know yet
We do not publish which restaurants require how much notice, or how far ahead each opens its book. It changes with attention, season and ownership.
What does not change is the structure: group size, day, hour and neighbourhood decide far more than popularity does.