Offers with caps
An uncapped offer has one price: whatever the biggest cart decides. Caps flip that — the offer states in advance the most it will ever give, so you can advertise generously and spend precisely. PromoLock has five caps, each bounding a different thing. This playbook covers the flagship construction first, then the rest of the toolbox. (Already running offers without caps? Caps from your order history derives each cap from what the offer actually paid out.)
The flagship: XX% off up to $YY, over $ZZZ
Section titled “The flagship: XX% off up to $YY, over $ZZZ”A huge-feeling headline whose real payout you fixed in advance:
Get 40% off, up to $30, on orders over $150.
Sounds like a blowout; pays out 20% at best. All three numbers come from your store’s average order value (Shopify admin → Analytics; say it’s $70):
| Number | Rule of thumb | Example (AOV $70) |
|---|---|---|
| Min spend | 1.5–2× AOV — forces an extra item into the cart, still feels reachable. | $150 |
| Cap | What a qualifying order should really cost you: 15–20% of the min spend. | $30 |
| Headline % | Roughly double your real rate, rounded to a dramatic number. | 40% |
Because 40% of $150 is $60 and the cap is $30, the cap kicks in on every qualifying order — nobody ever receives 40%:
| Cart | You pay | Effective rate |
|---|---|---|
| $120 | doesn’t qualify — customer adds an item | — |
| $150 | $30 | 20% |
| $200 | $30 | 15% |
| $300 | $30 | 10% |
Flat $30 per redemption, minimum $150 in revenue, advertised at 40%. Meanwhile the same headline with no minimum pays the full 40% on every small cart that was checking out anyway — the subsidy this construction exists to avoid.
Build it: Code discount → Condition: Cart subtotal · Greater than · 150 → Order discount · Percentage off · 40 with Max discount amount 30 → tick Cap total discount 30 in Margin guards as the backstop → Combines with all off → market it with all three numbers visible.
The rest of the toolbox
Section titled “The rest of the toolbox”Different offers leak differently — pick the cap that bounds your offer’s failure mode.
Quantity limit — “per customer” without saying it
Section titled “Quantity limit — “per customer” without saying it”Where: a product discount’s Quantity limit field. Caps how many units per line get the discount.
30% off hoodies — up to 2 per order. A reseller loading 40 hoodies into a cart gets the discount on exactly 2. The offer stays attractive for humans and useless for bulk-buyers, with no rules or fraud tooling involved.
Item limit + Applies to — the “cheapest item” family
Section titled “Item limit + Applies to — the “cheapest item” family”Where: a product discount’s Applies to select (All items / Cheapest / Most expensive) plus Item limit.
Buy 3, cheapest one 50% off — Applies to: Cheapest, Item limit: 1, with a Cart quantity · Greater than · 2 condition. The classic bundle-driver, and the cap is structural: however big the cart, exactly one line is ever discounted. Flip to Most expensive for premium-pushing offers where the discount should reward the big purchase, not the sock.
Max per item — tiers that can’t be gamed by price
Section titled “Max per item — tiers that can’t be gamed by price”Where: a product discount’s Max per item money field (percentage discounts).
20% off everything in Apparel, up to $25 per item. The $500 designer coat gets $25 off, not $100. Percentage offers on catalogs with a wide price spread need this — the cap keeps the offer’s cost proportional to your typical item, not your most expensive one.
Cap total discount — the ceiling over everything
Section titled “Cap total discount — the ceiling over everything”Where: Margin guards → Cap total discount. One number that bounds the whole discount — every tier, every group, every part — trimmed proportionally if the parts add up past it.
This is the cap to set even when you think you don’t need one. Tiered offers, multi-group offers, anything with several moving parts: the global cap is what guarantees the parts can never compound into a number you didn’t sign off on. The tiered discount guide uses it exactly this way.
Choosing quickly
Section titled “Choosing quickly”| Your offer | The cap that bounds it |
|---|---|
| Big headline percentage | Max discount amount + min-spend condition (the flagship) |
| Category/collection percentage | Max per item |
| Free/discounted item promos | Applies to + Item limit |
| Anything bulk-buyable | Quantity limit |
| Anything with multiple parts | Cap total discount — always |
Pitfalls
Section titled “Pitfalls”- Min spend at or below your AOV on the flagship — you’re subsidizing orders that were already happening. Stay at 1.5× or above.
- Stretching the headline past ~2–3× the real rate. A 60% headline that pays 10% reads as bait at checkout, and bait converts once.
- Hiding the caps from marketing. “Up to $30”, “max 2 per order” — state them wherever the headline appears; a customer discovering a cap at checkout is a support ticket.
- Leaving Combines with on. A second code stacked on top un-caps everything. Keep the flags off and the stacking lock on.