The math & the assumptions

How BookDeposit works

BookDeposit turns a handful of numbers about your bookings into a clear answer to one question: how much are no-shows costing you, and how much would a deposit protect? This page lays out the exact formulas, the assumptions you’re in control of, and how to read the result honestly.

Privacy
The inputs
The math
The reduction assumption
How to use the result
Not financial advice
What’s next

Everything runs in your browser

BookDeposit has no backend. When you type your numbers in, every byte stays on your machine — the whole calculation happens in JavaScript, locally, in the tab you’re looking at. Nothing is uploaded, logged, stored, or sent to any server.

No network requests with your data. Your booking figures are never transmitted anywhere.
No storage. Reload the page and your numbers are gone. There’s no database and no signup.
Works offline. Load the page once, disconnect, and the calculator still runs — the simplest proof there’s nothing to upload to.

Verify it yourself. Open your browser’s developer tools, switch to the Network tab, and run a calculation. You won’t see a request carrying your input — because there isn’t one. The only network activity on the whole site is loading the page, its stylesheet, the script, and the web fonts.

The inputs

Input	What it means
Appointments per week	The bookings you take in a typical week.
Average booking value	The revenue a single completed booking brings in, in your currency.
No-show rate	The share of bookings that don’t turn up (and that you can’t rebook or recover).
Working weeks per year	The weeks you actually take bookings — drop holidays and closures.
Proposed deposit	What you’d ask for up front to hold a slot — a flat amount or a percentage of the booking.
Assumed no-show reduction	How much you expect a deposit to cut your no-show rate. This one is your call — see below.

The math, step by step

First we work out today’s cost of no-shows:

bookings/yr = appointments per week × working weeks no-shows/yr = bookings/yr × no-show rate revenue lost = no-shows/yr × average booking value

Then we model what happens once a deposit is required. Your no-show rate drops by the reduction you set, the clients who now show up are worth their full value again, and the no-shows that remain forfeit their deposit instead of costing you the whole slot:

new no-show rate = no-show rate × (1 − reduction) no-shows/yr (new) = bookings/yr × new no-show rate recovered bookings = old no-shows − new no-shows recovered revenue = recovered bookings × average booking value forfeited deposits = new no-shows × deposit amount revenue protected = recovered revenue + forfeited deposits remaining loss = new no-shows × (booking value − deposit amount) net annual gain = revenue protected

A few deliberate choices keep the model honest. If you enter the deposit as a percentage, the deposit amount is that percentage of the average booking value. A deposit is never allowed to exceed the booking value. And the “net annual gain” is measured against doing nothing — it’s simply the revenue you stop losing.

The reduction assumption is yours to set

This is the number that swings the result the most — so the tool puts it in your hands rather than baking in a figure that flatters the answer.

Requiring money up front reliably reduces no-shows: once a client has paid something toward a booking, the cost of skipping it is no longer zero, and the booking feels more like a commitment. Many businesses that introduce deposits report a large drop in no-shows. But the exact reduction depends on things only you know — how price-sensitive your clients are, how big the deposit is, how clearly you communicate the policy, and whether deposits are refundable.

Because of that, BookDeposit asks you for the reduction rather than guessing. The practical approach: run the numbers with a conservative reduction and an optimistic one, and make your decision on the range rather than a single hopeful figure.

How to use the result

Start from today’s loss. The “lost to no-shows” figure is the cleanest one — it depends only on facts about your current business, not on any assumption.
Stress-test the reduction. Try a pessimistic reduction. If a deposit still pays off at, say, a modest cut, the policy is an easy call.
Size the deposit deliberately. A bigger deposit forfeits more when someone no-shows, but too large a deposit can deter genuine bookings. Try a few sizes and watch the protected figure.
Share the card. Copy the result summary to talk it through with a partner, manager, or accountant before you change your policy.

This is a planning tool, not financial advice

Important: BookDeposit gives you an estimate to reason with — it is not financial, accounting, tax, or legal advice, and it is not a guarantee of results.

The model is deliberately simple, which means it leaves things out: refunds and partial refunds, payment-processing fees and chargebacks, taxes, seasonality, the chance that some no-shows would have cancelled in time to rebook anyway, and how your specific clients will actually react to being asked for a deposit. Use the output as a starting point for a decision, sanity-check it against your own books, and consult a professional for anything that affects your finances materially.

What’s next: actually collecting the deposits

From estimate to reality. This calculator is the free first step. The product we’re building takes the deposit at the moment of booking, sends automated reminders, syncs to your calendar, and gives you an embeddable booking widget for your own site — so the savings you see here stop being a projection and start being money in the bank. Tell us about your business →

Calculate my no-show cost