Capable to Promise (CTP) is a commitment check that goes beyond available inventory: it asks whether the business can produce the units required to fulfill an order within the customer's required date, given current materials, capacity, and lead times. Where Available to Promise (ATP) answers "do we have it?", CTP answers "can we make it in time?"
CTP is most relevant to make-to-order, configure-to-order, and assemble-to-order businesses. The check evaluates:
If the answer to all three is yes, the order is capable to promise. If not, CTP returns either a later promise date or a "cannot fulfill" signal — both more useful than the false confidence of a stock-only check.
CTP is the difference between a date you can keep and one that turns into a refund. A stock-only check will happily sell four weeks of production capacity in a single afternoon if a sale or a press mention lands. The orders past capacity become late shipments, then support tickets, then cancellations, and — once a customer gives up and calls their bank — chargebacks, each carrying a fee and counting against the ratio that decides whether you keep your payment processor. The money moves the other way too: a specific, capacity-aware date on the product page converts better than a vague one, because a buyer who needs the item by a certain day will not risk an order that refuses to commit to one. The trade-off is that an honest date is sometimes further out than a competitor's optimistic one, and the brand quoting the further date keeps the margin the other one refunds.
CTP becomes critical for any Shopify brand that doesn't sell purely from finished-goods stock. Common cases:
For these models, ATP alone produces unrealistic promises. A storefront might show 50 units "available" because the components exist, but if production capacity is booked for the next four weeks, the actual deliverable date is much further out than the storefront suggests.
Most Shopify brands operate primarily at the ATP level. Brands with production complexity layer CTP on top via an ERP or manufacturing planning system. PTP is rare in pure ecommerce and more common in industrial B2B.
CTP requires a system that can simulate forward production scheduling — typically an ERP or dedicated manufacturing planning module (MRP). The system holds:
When a new order comes in, the system runs a forward simulation to check if all required components and capacity will be available before the customer's promise date. If yes, the order is committed and consumed against capacity. If not, the system either returns a later date or rejects the commitment.
CTP only earns its keep when the answer reaches the customer. A capacity-aware date calculated in the back office and then hidden behind a generic "ships in 3–5 days" line on the product page changes nothing except internal reporting. The build order is the capacity model first, through Shopify ERP integration, then the storefront and checkout side — shipping and delivery optimization — that surfaces the real date at the moment the customer is deciding whether to buy.
Whether a brand can run CTP at all usually comes down to which ERP it’s on, since the forward-scheduling simulation the check requires isn’t something a stock-only system can bolt on after the fact. For a comparison of what different ERP systems actually support and what integrating one into Shopify involves, see this guide to ERP integration for Shopify.
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