ERP & MRP Planning calculator
Available to Promise Calculator
Available to Promise helps customer service, sales, and planners decide how many units can be promised without stealing from existing commitments. It should be calculated from the same item, site, and availability bucket.
What this calculator does
- Estimate available-to-promise quantity after firm sales allocations, safety stock, and quality holds.
- a planner needs to know how many units can still be promised to new demand
- It calculates the quantity still available for new promises after existing commitments and reserves.
Formula used
- Available to promise = available supply - firm allocations - protected safety stock - quality hold or blocked stock
- ATP should be checked again if receipts, allocations, or quality status change.
Inputs explained
- Available supply before new order: Use on-hand plus firm receipts available in the promise bucket.
- Firm sales order allocations: Subtract committed customer orders, reservations, and allocation holds.
- Protected safety stock: Subtract safety stock that should not be consumed by normal promise decisions.
- Quality hold or blocked stock: Subtract inventory in inspection, quarantine, blocked status, or pending disposition.
How to use the result
- Use it during ERP cleanup, MRP review, production scheduling, S&OP prep, purchasing decisions, shortage meetings, capacity planning, or daily shop-floor execution reviews.
- This is a planning estimate. Confirm final commitments against current ERP/MRP records, released BOMs and routings, inventory accuracy, supplier commitments, open work orders, quality holds, and shop-floor constraints.
Common questions
- What is the Available to Promise calculator for? It calculates the quantity still available for new promises after existing commitments and reserves.
- What information do I need before using it? You need available supply, firm allocations, protected safety stock, and blocked or quality-hold inventory.
- How should I use the result? Use it to confirm or decline new customer orders, split shipments, or escalate supply constraints.
- When is the result only an estimate? It is only an estimate when demand, inventory, lead time, routing hours, setup time, yield, supplier dates, or work-center capacity comes from forecast assumptions or stale ERP data instead of current orders and recent execution history.
Last reviewed 2026-05-12.