Your supplier confirmed capacity. But they confirmed it to three other customers too.
A planning team built around that commitment, confirmed Q4 capacity, allocated volumes, made solid customer promises on the back of that.
Six weeks later the supplier called. Their capacity was not available. The supplier had a larger customer. When the schedule got tight, that customer came first.
The problem is overcommitment, not dishonesty. Most suppliers believe it when they say it.
A capacity commitment means something different to the supplier than it does to the buyer.
To the buyer: this volume is reserved, protected, and will be delivered.
To the supplier: at the time of this conversation, we believe we can do this.
Those are not the same thing. And the gap between them only becomes visible when something goes wrong.
Three Questions That Tell You Whether a Commitment Is Real
1. Is this capacity dedicated or shared?
Dedicated — a line, a shift, a slot reserved for your volume — is a commitment.
Shared — we have enough overall to fit you in — is an intention.
Ask directly. Most buyers never do.
2. What would cause this commitment to change?
A supplier who cannot answer this has not thought it through.
One who can answer specifically — “if this customer’s volume comes in above forecast, we would need a conversation” — is giving you real information. That answer tells you exactly where your risk sits.
3. When did you last run at this volume?
Capacity on paper and demonstrated capacity are different things.
A supplier who has never shipped at the volume they are committing to is not making the same promise as one who does it regularly.
None of these questions are adversarial. A supplier who takes their commitments seriously will have answers to all three.
The ones who do not — that is useful information too.