Understanding GCP's pricing model is essential both for managing real-world cloud costs and for passing the Cloud Digital Leader exam, which covers cloud economics extensively.
GCP Pricing Principles
- Per-second billing: Most compute resources (Compute Engine, Dataproc) are billed per second after a 1-minute minimum. No rounding up to the nearest hour.
- No egress within the same zone: Data transfer between resources in the same zone is free. Cross-region and internet egress incurs charges.
- Automatic discounts: Unlike AWS, GCP applies Sustained Use Discounts automatically — no action required.
- Free tier: Many services offer a free tier that never expires (e.g., 1 f1-micro VM per month, 5 GB Cloud Storage, 10 GB BigQuery storage).
Discount Types
| Discount | How It Works | Max Savings |
|---|---|---|
| Sustained Use Discount (SUD) | Automatic discount when a VM runs >25% of the month | Up to 30% |
| Committed Use Discount (CUD) — Resource | Commit to specific vCPU/RAM for 1 or 3 years | Up to 57% |
| Committed Use Discount — Spend | Commit to a minimum spend amount for 1 or 3 years | Up to 25% |
| Preemptible / Spot VMs | Use excess capacity; can be reclaimed at any time | Up to 91% |
| Free tier | Monthly always-free usage limits per service | 100% |
Important: Sustained Use Discounts and Committed Use Discounts do not combine on the same resource. Use CUDs for predictable workloads; SUDs apply automatically to everything else.
Billing Hierarchy
- Billing account: Linked to a payment method (credit card, invoice). You can have multiple billing accounts in an organisation.
- Projects: Each project is linked to exactly one billing account. All resource costs in the project are charged to that billing account.
- Invoicing: Enterprise customers can be invoiced monthly instead of charged to a card.
Budgets and Alerts
Budgets in GCP notify you when actual or forecasted spend exceeds thresholds. Best practices:
- Set a budget per project or per billing account
- Configure alerts at 50%, 90%, and 100% of budget
- Route budget notifications to Pub/Sub to trigger automated actions (e.g., stop non-critical VMs)
Pricing Calculator
The Google Cloud Pricing Calculator lets you estimate costs for any combination of GCP services before deploying. It's especially useful for:
- Estimating migration costs
- Comparing configurations (e.g., N2 vs E2 machine types)
- Modelling committed use discount savings
Shared Responsibility Model
As with all cloud providers, security responsibilities are shared between GCP and the customer:
| GCP Responsibility | Customer Responsibility |
|---|---|
| Physical security of data centres | IAM and access control configuration |
| Hardware and network infrastructure | Application security and code |
| Hypervisor and managed service patches | OS patching (for Compute Engine VMs) |
| Data encryption at rest and in transit (default) | Customer-managed encryption keys (optional) |
Ready to test your GCP knowledge?
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