agent's GCP committed-use math used list price, sustained-use discounts were already applied

TL;DR

GCP applies sustained-use discounts automatically, so the rate you actually pay is already below list. Commitment math must start from that billed rate. Any recommendation that compares the committed rate against list price is double-counting a discount you already get for free.

agent's gcp committed-use math used list price, sustained-use discounts were already applied

Use this when

• A committed-use discount recommendation shows savings that look too good.
• The math compares the CUD rate against the public list price.
• Actual billed savings after purchase come in far below the projection.

Not for this skill when

• The workload has no sustained usage (spiky, short-lived). List price is close to the real baseline there.
• You are comparing committed-use against a negotiated contract rate. That comparison is valid if done explicitly.

Steps

1. Pull the actual billed rate for the workload from the BigQuery billing export or the Cloud Billing report. Verify: the rate reflects sustained-use discounts already applied.
2. Recompute the recommendation: (billed rate minus CUD rate) times committed usage. That is the real incremental saving.
3. Check the sustained-use discount percentage on the invoice; it varies by machine type and region.
4. Only commit the stable baseline portion of usage; spiky usage keeps earning sustained-use discounts without a commitment.
5. Re-run the math monthly for the first quarter after purchase to confirm realized savings match the projection.

Variant phrasings

committed use discount savings overestimated gcp

The billing-side phrasing.

sustained use discount vs committed use discount

The comparison question.

gcp cud recommendation used list price

The agent-mistake framing.

Compatibility: Google Cloud committed-use discounts for Compute Engine; sustained-use discounts apply automatically to eligible usage.

Why it happens

List price is the easiest number to fetch, so recommendation scripts fetch it. But sustained-use discounts are invisible in the SKU price and very visible on the invoice. Math built on list price promises savings on top of savings you already have.

Edge cases / pitfalls

• Sustained-use discounts do not apply to all machine types (sole-tenant and some others are excluded). Check eligibility per workload.
• Flexible CUDs changed the math again: know which commitment type the recommendation assumed.
• Currency and region both shift the billed rate; pin both when you baseline.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_fR-JANkMaVRlA8BPxRlOcA