ATP (available-to-promise)
ATP — Available-to-Promise
Reliable delivery commitments based on real availability
1. Overview
Order promising helps you reliably commit delivery dates to customers and gives flexibility to meet those dates. It calculates the earliest shipping date (sales orders) or receipt date (purchase and transfer orders) based on the Delivery date control method and transport days.
Think of it like a promise you can keep
You do not promise what you cannot deliver — you check stock, incoming supply, and existing commitments before quoting a date.
2. How ATP Works — Cumulative ATP with Look-Ahead
ATP uses the cumulative ATP with look-ahead method. Supply and demand are evaluated over time to find the first date when the available quantity is equal to or greater than the requested quantity.
The 5-step flow
- Collect Supply — On-hand inventory and planned receipts (considering lead times).
- Collect Demand — Existing customer orders and planned issues.
- Calculate Cumulative Available Quantity — Supply minus demand over time.
- Find ATP Date — First date when quantity ≥ requested quantity.
- ATP Result — Earliest ship or receipt date and quantity available.
3. Delivery Date Control Methods
You can select among the following methods to calculate promised delivery dates:
| Method | What it Considers |
|---|---|
| Sales Lead Time | A default lead time between order creation and shipment. Does not consider inventory, demand, or supply. |
| ATP (Available-to-Promise) | Considers uncommitted inventory, lead times, planned receipts, and issues to find the earliest available date. |
| ATP + Issue Margin | ATP date plus an issue margin (extra preparation time) required to ship the items. |
| CTP (Capable-to-Promise) | Availability calculated through explosion of BOM and routing (considers components and capacity). |
| CTP for Planning Optimization | Uses Planning Optimization CTP calculation. Has no effect if using the built-in master planning engine. |
4. ATP Calculation Example
Example: Item A · Warehouse 1 · Requested Qty = 150 · Today = Day 0
| Day | On-hand | Planned Receipts | Customer Demand | Cumulative ATP | ATP Result |
|---|---|---|---|---|---|
| Day 0 | 100 | — | — | 100 | — |
| Day 2 | — | 50 | — | 150 | — |
| Day 3 | — | — | 80 | 70 | — |
| Day 5 | — | 100 | — | 170 | — |
| Day 6 | — | — | 120 | 50 | — |
| Day 8 | — | — | — | 50 | — |
| Day 9 | — | — | — | 50 | — |
| Day 10 | — | 120 | — | 170 | ATP Date = Day 10 ATP Qty = 150 |
5. Key Inputs Considered
On-hand Inventory
Uncommitted, usable inventory currently in the warehouse.
Planned Receipts
Purchase orders, production orders, transfer orders, and returns.
Existing Demand
Sales orders and other planned issues.
Lead Times
Vendor lead time, production lead time, and transfer time.
Transport Days
Time required to physically ship items to the customer location.
6. Important Notes
Recalculation Rule
When a sales order is updated, order promising is only recalculated if the existing promised date can no longer be fulfilled.
Example 1 — Triggered
- Current ATP date = July 20
- Quantity increased → cannot deliver until July 25
- ATP IS recalculated to July 25
Example 2 — Not Triggered
- Current ATP date = July 20
- Quantity decreased → could deliver on July 15
- Current date can still be met → ATP NOT recalculated
Known Limitation
7. Benefits of ATP
- Reliable delivery commitments to customers.
- Improved customer satisfaction through accurate promises.
- Prevents over-selling of inventory.
- Better supply chain visibility.
- Optimized inventory and capacity utilization.
8. Where ATP Is Used
🛒 Sales Orders
- Promise reliable ship dates to customers.
📦 Purchase Orders
- Promise realistic receipt dates from vendors.
🔄 Transfer Orders
- Promise receipt dates at destination warehouse.
🏭 Production
- Confirm component availability before scheduling.
🎯 Key Takeaway
ATP helps organizations make confident, accurate, and achievable delivery commitments by aligning real inventory, future supply, and demand over time.