Stamp card or monthly plan: the math for a single-bay car wash

The short answer, then the math

For most single-bay washes, start with a stamp card and add a monthly plan later, if at all. A stamp card costs you roughly 6 SAR of margin per wash and carries almost no downside. An unlimited monthly plan can earn far more per customer, and it can also fill your only bay with cars that have already paid.

The number that decides between them is average washes per subscriber per month. You almost certainly do not have that number yet, and no vendor can hand it to you. Everything below is one worked example with the assumptions written out, so you can drop your own prices in.

Here are the assumptions. A standard exterior wash sells for 40 SAR. Water, chemicals, towels, and the paid labor minutes come to about 12 SAR a car, so each wash leaves 28 SAR of contribution. One bay, 20 minutes a car, open 12 hours a day, 26 days a month.

That gives you 36 slots a day, or about 936 a month at full tilt. Say you actually wash 18 cars a day, around 470 a month. Half your bay time is empty, and that spare half is the single biggest input into the decision.

What a 6+1 stamp card really costs you

Take the common structure: buy six washes, the seventh is free. Over a completed cycle you collect 6 x 40 = 240 SAR and deliver seven washes. Consumables run 7 x 12 = 84 SAR. You keep 156 SAR across seven washes, or about 22 SAR a wash.

So the sticker discount is 14%, one wash in seven. But your contribution per wash drops from 28 SAR to 22 SAR, which is a 20% cut. Discounts land on margin, not on price. That gap is the number worth memorizing before you print anything.

Now the bar the card has to clear. Say a regular washes every three weeks, 17 times a year, worth 476 SAR of contribution. At 22.3 SAR a wash you need 21.4 washes to match that, which is about 26% more often, or four and a half extra visits a year. If the card does not change behavior at all, a completing customer is slightly worse for you than a walk-in.

Two things rescue the math in practice. The first is breakage: a customer who collects three stamps and drifts away costs you nothing and still came three times. The second is card length. At nine paid washes plus a free tenth, contribution rises to 24 SAR a wash and the bar falls to roughly 17% more visits, but fewer people finish a longer card. You are trading reach for margin.

Where an unlimited monthly plan breaks

Price the plan at 199 SAR a month for unlimited exterior washes. Your effective price per wash is just 199 divided by how often they show up. Two washes a month is 99.50 SAR a wash. Four is 49.75 SAR. Six is 33.17 SAR. Ten is 19.90 SAR.

On consumables alone the plan looks excellent for a long time. Contribution is 199 minus 12 per wash: 175 SAR at two washes, 127 SAR at six, 79 SAR at ten. The same person as a walk-in at two washes a month leaves you 56 SAR. On chemicals and towels, the plan wins until about 16 washes a month.

Consumables are not your only cost. The slot is. If the bay is busy at the hour your subscriber arrives, that wash displaced a walk-in worth 28 SAR. Then the plan only beats walk-in pricing while 199 divided by washes stays above 40 SAR, which means fewer than 5 washes a month. Same price, same plan: profitable up to 16 washes in an empty bay, underwater past 5 in a full one.

Heavy users find plans quickly. Rideshare and delivery drivers wash three or four times a week, so two of them can absorb 30 slots a month on their own. The usual fixes are worth deciding up front: bind the plan to one license plate, cap the washes and stop calling it unlimited, keep interior work paid separately, and consider excluding Thursday evening through Saturday. In Saudi Arabia the weekend is Friday and Saturday, so the rush starts Thursday night and that is exactly when subscribers want their turn.

The third option most washes skip

There is a middle model that gets ignored: the prepaid pack. Ten washes for 360 SAR is a 10% discount, leaves 24 SAR of contribution per wash, and puts 360 SAR in your hand today. Your liability is capped at ten washes and cannot run away from you.

Cash up front matters for a one-bay operation. It buys the pressure washer or covers a slow month, and there is no monthly charge to chase. The pack simply runs out and you sell another one, so nobody has to remember a renewal date.

The honest downside is behavioral. A monthly subscriber washes because the next wash feels free, so the plan builds a habit. A pack holder rations what they bought and often washes no more often than before.

Which model suits which location

A neighborhood or residential-compound wash with dead weekday mornings is the best case for a monthly plan. Your trough absorbs subscriber washes at close to zero opportunity cost, and residents who park within two kilometers have stable, predictable habits.

A wash on a busy commercial strip or in mall parking, with a queue on your only bay at the weekend, should stay on a stamp card or a prepaid pack. Your slots are already worth 28 SAR each at precisely the hours subscribers want them, so selling those hours at 33 SAR a wash is not a good trade.

A petrol-station bay on a highway is probably neither, and the cheapest way to find out is to run a stamp card for two months and count how many plates come back. Mobile wash crews are a different constraint again: drive time, not bay time, so a plan only works with several subscribers inside one district. Fleets, rideshare, and delivery cars belong on a separate per-car rate, never on the consumer plan.

One local factor deserves its own line. In Riyadh and the Eastern Province, a dust event makes every car in the city filthy within 24 hours. Subscribers and walk-ins arrive on the same two days, and you can still only wash one car at a time. If your city gets dust, keep more headroom than the arithmetic suggests.

A 60-day way to stop guessing

Run the stamp card first, for 60 days, before you design a subscription. On Waya's free plan that costs 0 SAR: up to 100 customers, one stamp card, one branch, 100 wallet messages a month, no credit card. Enrollment is a QR code taped by the bay. The customer types a first name and mobile number and taps once to add the card to Apple Wallet or Google Wallet, with a web card for anything else. They install nothing.

Then read washes per customer per month off the dashboard and sort by frequency. Your top 10% is the planning case, because those are the people who will buy a monthly plan. If that group washes six times a month and your bay is busy, an unlimited plan has to price above 240 SAR or it has to carry a cap.

Finally, launch the plan to about 20 customers for one month before you advertise it anywhere. Then go stand in the bay at 6pm on a Thursday and watch the clock. Sign-ups tend to cluster at the end of the Gregorian month, when most salaries land, so time the offer for the last week.

What Waya does here, and what it does not

Waya puts the card in the customer's wallet. It does not take the money. There is no POS or till integration, no card processing for your subscription, and no SMS. You collect the 199 SAR the way you already collect money, at the till, by bank transfer, or with your own payment link, and the pass carries the membership and the renewal date.

Verification is the part that genuinely beats paper. Your cashier scans the customer's pass on an ordinary phone in about ten seconds, with no clipboard of plate numbers to search. A prepaid pack runs on a balance card, one wash deducted per scan. If you want the stamp card and a membership card running side by side, that is the Growth plan at 85 SAR a month: unlimited customers, up to 10 cards, 3 branches, 5 staff accounts, and 5,000 wallet messages.

Reminders arrive without SMS. Wallet passes update themselves and messages land on the lock screen, and there is a passive branch-proximity reminder you configure on the Branches screen. That is how a subscriber who has not come in for ten days gets nudged while driving past. On paid plans the metered number is wallet messages, not customers.

For price context, as of August 2026 Btaqa publishes tiers at 108, 250, and 380 SAR a month, OneCup sits around 150 SAR, Watily is 149 SAR with loyalty bundled into a wider plan, and Niqati, the best-known name in the Saudi market, quotes per shop. Check each of these yourself, because vendor pricing moves. The structural difference is the order of operations: those all begin with a paid subscription, while Waya starts at 0 SAR up to 100 customers, which is what you want while you are still measuring how often your customers actually wash.