Capable to Promise (CTP)

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?"

What CTP means

CTP is most relevant to make-to-order, configure-to-order, and assemble-to-order businesses. The check evaluates:

• Component availability: are all the raw materials and sub-assemblies in stock or arriving in time?
• Production capacity: is there enough machine time, labour, or assembly capacity to produce the order on schedule?
• Cumulative lead time: if any input is missing, can it be sourced and integrated before the customer's required date?

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.

Why CTP matters in ecommerce

CTP becomes critical for any Shopify brand that doesn't sell purely from finished-goods stock. Common cases:

• Custom or personalised products: engraving, embroidery, made-to-measure apparel, custom configurations.
• Built-to-order furniture or hardware: finished from base components on order.
• Bundles assembled on demand: kits packed when ordered rather than pre-assembled.
• Pre-orders that depend on incoming production runs: the inventory doesn't exist yet, but production is scheduled.

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.

ATP vs. CTP vs. PTP

• ATP: based on existing or scheduled inventory only.
• CTP: incorporates production capacity and component lead times; answers "can we make it?"
• Profitable to Promise (PTP): a further extension that also asks "should we?" — evaluating whether the order's margin justifies the resources consumed.

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.

How CTP is implemented

CTP requires a system that can simulate forward production scheduling — typically an ERP or dedicated manufacturing planning module (MRP). The system holds:

• Bill of Materials (BoM) for each finished product
• Component inventory and incoming PO schedule
• Production capacity by line, machine, or labour pool
• Existing scheduled production commitments

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.