Object storage cost compared: S3 vs Cloud Storage vs Blob

Quick answer

S3, Google Cloud Storage, and Azure Blob all price object storage the same way: tiered storage (standard down to archive), request charges, and egress. Storage rates for the standard tier are similar across all three (around $0.02/GB-month). The decisive difference is usually egress, which is expensive on all three and the main reason a naive multi-cloud data strategy costs more than expected.

The three major clouds each offer object storage, and at a high level they are priced identically: you pay to store, to make requests, and to move data out. The storage rates are close enough that storage is rarely the deciding factor. Egress is, and understanding it prevents the most expensive object-storage mistakes.

The shared pricing model

Component	S3	Cloud Storage	Blob
Standard storage	~$0.023/GB-mo	~$0.02/GB-mo	~$0.018/GB-mo
Tiers	IA, Glacier, Deep Archive	Nearline, Coldline, Archive	Cool, Cold, Archive
Requests	Per 1,000	Per 1,000/10,000	Per 10,000
Egress	Tiered per GB	Tiered per GB	Tiered per GB

All three offer hot-to-archive tiers with cheaper storage but higher access cost as you go colder, per-request charges, and lifecycle policies to move data automatically. The standard storage rates are within a small margin of each other, so storage rarely decides the choice.

Egress is the decisive cost

Egress, data leaving the cloud to the internet or another region, is expensive on all three and dwarfs storage for data that is read a lot or served externally. Serving large volumes directly from object storage racks up egress, which is why a CDN in front usually lowers total cost. A multi-cloud strategy that moves data between providers pays egress every time, which is the single biggest reason such strategies cost more than the storage rates suggest. See data transfer across clouds for the detail.

Which is cheapest?

For storage alone, the three are close, and the cheapest depends on tier, region, and volume, small differences that rarely justify choosing a provider on storage price. The real cost drivers are egress and requests, and keeping data in the same cloud and region as the workloads that read it, with a CDN for external serving, matters far more than the per-gigabyte storage rate.

Choosing and optimizing

Choose object storage in the cloud where your compute lives, to avoid cross-cloud egress. Use tiers and lifecycle policies to match storage class to access frequency, front external serving with a CDN to cut egress, and minimize small-request and cross-region patterns. The optimizations are the same across all three, because the pricing models are.

FAQ

Is S3, Cloud Storage, or Blob cheapest?

For standard storage they are close, around $0.018 to $0.023 per GB-month, and the cheapest depends on tier, region, and volume, differences too small to decide a provider on storage price alone. The decisive cost is egress, which is expensive on all three, so keeping data near the compute that reads it matters more.

How do S3, Cloud Storage, and Blob pricing compare?

Nearly identically in model: tiered storage (hot to archive) with cheaper storage but higher access cost as tiers get colder, per-request charges, and tiered egress. The standard storage rates are within a small margin, and all three offer lifecycle policies. Egress and requests, not storage, drive the difference in practice.

Why does egress dominate object storage cost?

Because egress (data leaving the cloud to the internet or another region) is expensive on all three providers and applies every time data is read externally or moved. For frequently-read or externally-served data, egress dwarfs the storage rate, which is why a CDN in front usually lowers total cost.

Does multi-cloud object storage save money?

Rarely on cost alone, and often it costs more, because moving data between providers pays egress every time, and egress is the dominant object-storage cost. A multi-cloud data strategy should be driven by resilience or specific needs, not storage price, since the storage rates are similar and the egress is expensive.

How do I reduce object storage cost across clouds?

Keep object storage in the same cloud and region as the compute that reads it to avoid cross-cloud and cross-region egress, use tiers and lifecycle policies to match storage class to access frequency, front external serving with a CDN to cut egress, and minimize small-request patterns. The optimizations are the same across S3, Cloud Storage, and Blob.

Does C3X estimate object storage cost across clouds?

C3X prices object storage resources (S3, Cloud Storage, Blob) from your Terraform against a live catalog. Because storage tier, request, and egress cost depend on data volume and access patterns, you provide those as usage assumptions to compare across providers.

What to do next

Compare storage across clouds for your workload. C3X reads your Terraform and prices your resources against a live catalog. Start with the quickstart.