Amazon S3 vs Azure Blob Storage
SEPT 2026 auditA comparison of Amazon S3 and Azure Blob Storage built from values read directly from each provider's own documentation, with the source recorded against every figure.
The short answer
Choose Amazon S3 if…
Workloads already inside AWS, where keeping data in the same region as the compute avoids the transfer charges that dominate an object storage bill.
Editorial · Palash Bagchi · approved
Choose Azure Blob Storage if…
Workloads already on Azure, where keeping storage in the same region as the compute avoids the bandwidth charge that dominates an object storage bill.
Editorial · Palash Bagchi · approved
Consider something else if…
- Amazon S3: Egress is the cost that decides this category and S3 charges for it, where R2, Wasabi and Tigris do not. Prices also vary by region, so a figure quoted anywhere is only true for the region it was read in.
- Azure Blob Storage: Egress is charged beyond the first 100 GB a month, where R2, Wasabi and Tigris charge nothing — and Azure's rates vary by region and redundancy, so a quoted figure only holds for the combination it was read for.
Neither quite fits? Every other option, ranked by iScore: Amazon S3 alternatives · Azure Blob Storage alternatives
15 sourced criteria separate them — see where, with sources, below.
Pick the criteria you care about. The chart counts how many of them lean toward each provider — the same read as scanning the bars below, just totalled for the ones you chose.
Amazon S3 0
Azure Blob Storage 0
At a glance.
| Criterion | Amazon S3 | Azure Blob Storage |
|---|---|---|
| Pricing | ||
| Free tier | Yes | No |
| Kind of free offer | Introductory free tier | Free credit |
| What the free plan includes | 100 GB a month of data transfer out to the internet, counted globally rather than per region. Storage itself is billed from the first byte. | $200 of Azure credit for 30 days on a new account. Azure separately lists services that are always free and services free for 12 months to new customers, which is an account-wide programme rather than a Blob Storage allowance. |
| When the free offer ends | 6 months after account creation; Free Tier credits expire 12 months after that date. | 30 days. |
| Pricing model | Per region and per storage class, with storage, requests, retrievals, data transfer and management features each metered separately. AWS states there is no minimum charge, and bills storage in binary gigabytes — 1 GB is 2^30 bytes, not 10^9. | Per region, per redundancy and per access tier, with storage, operations and egress metered separately; no plans and no bundles. |
| Egress over allowance | $0.09 per GB for the first 10 TB a month out to the internet, after a free 100 GB aggregated globally. It falls to $0.085 above 10 TB, $0.07 above 50 TB and $0.05 above 150 TB. This is AWS's outbound data transfer rate rather than an S3-specific one — the charge that R2, Wasabi and Tigris do not levy at all. | First 100 GB a month free, then $0.087 per GB over Microsoft's global egress meter, falling to $0.083 above 10 TB. |
| Limits | ||
| Storage (entry plan) | None. S3 has no plans and no included storage — AWS states there is no minimum charge and you pay only for what you use, billed per GB-month from the first byte. New accounts get AWS Free Tier credits ($100 immediately, up to $200 over six months) which are spendable credit rather than a standing storage allowance. | None. Azure Blob has no plans and no free storage band: the Hot LRS meter is charged from the first GB. |
| Infrastructure | ||
| Uptime SLA | 99.9% for S3 Standard, Express One Zone and the Glacier retrieval classes; 99.0% for Intelligent-Tiering, Standard-Infrequent Access, One Zone-IA and Glacier Instant Retrieval. | Not published as a web page. Microsoft consolidated its per-service SLAs into one downloadable document covering Azure, Dynamics 365, Office 365 and Intune; the former azure.microsoft.com SLA URLs now redirect to its licensing viewer. |
| Storage | ||
| Storage price | $0.023 per GB-month for S3 Standard, first 50 TB, in us-east-1. S3 prices vary by region; this and every other S3 figure on the site is that region. | $0.0208 per GB-month for Hot LRS in East US, falling to $0.019968 above 50 TB and $0.019136 above 500 TB. |
| Operations price | $0.005 per 1,000 PUT, COPY, POST and LIST requests, and $0.004 per 10,000 GET and all other requests, in us-east-1. DELETE and CANCEL are free. | $0.05 per 10,000 write operations and $0.004 per 10,000 reads on Hot LRS in East US. |
| Minimum storage duration | None on S3 Standard. 30 days on Standard-IA and One Zone-IA, 90 days on Glacier Instant and Flexible Retrieval, 180 days on Glacier Deep Archive, each with a pro-rated charge for early deletion. | None on Hot. Cool carries a 30-day minimum, Cold 90 days and Archive 180 days — the longest early-deletion window of any provider here, and three times S3's 90-day Glacier figure. |
| Compliance | ||
| SOC 2 | Listed as SOC-compliant on AWS's own compliance scope page. | Listed among Azure's compliance offerings (SOC 1, SOC 2, SOC 3) on Microsoft's own compliance documentation — a platform-wide list, not scoped to this specific service. |
| ISO 27001 | Covered under AWS's account-wide ISO/IEC 27001:2022 certification — not scoped per-service the way SOC, HIPAA and PCI DSS are on AWS's own site. | Listed among Azure's compliance offerings (ISO 27001) on Microsoft's own compliance documentation — a platform-wide list, not scoped to this specific service. |
| HIPAA | Listed as a HIPAA-eligible service on AWS's own reference page. | Listed among Azure's compliance offerings (HIPAA) on Microsoft's own compliance documentation — a platform-wide list, not scoped to this specific service. |
| PCI DSS | Listed as PCI DSS-compliant on AWS's own compliance scope page. | Listed among Azure's compliance offerings (PCI DSS) on Microsoft's own compliance documentation — a platform-wide list, not scoped to this specific service. |
Where they differ.
Free tier
- Amazon S3
- Yes
- Azure Blob Storage
- No
Sources (2) →Sources ↓
- S3 Pricing — AWS ↗
“Pay only for what you use. There is no minimum charge.”
Read 2026-09-06 · official docs · Report a correction
- Azure Blob Storage pricing ↗
“Get free cloud services and a $200 credit to explore Azure for 30 days.”
Read 2026-09-13 · official pricing · Report a correction
Kind of free offer
- Amazon S3
- Introductory free tier
- Azure Blob Storage
- Free credit
Sources (2) →Sources ↓
- Amazon S3 Pricing ↗
“At account sign-up, you can choose between a free plan and a paid plan. The free plan will be available for 6 months after account creation.”
Read 2026-09-13 · official pricing · Report a correction
- Azure Blob Storage pricing ↗
“Get free cloud services and a $200 credit to explore Azure for 30 days.”
Read 2026-09-13 · official pricing · Report a correction
What the free plan includes
- Amazon S3
- 100 GB a month of data transfer out to the internet, counted globally rather than per region. Storage itself is billed from the first byte.
- Azure Blob Storage
- $200 of Azure credit for 30 days on a new account. Azure separately lists services that are always free and services free for 12 months to new customers, which is an account-wide programme rather than a Blob Storage allowance.
Sources (2) →Sources ↓
- Amazon S3 pricing ↗
“The 100 GB free tier for data transfer out to the internet is global and does not apply separately or individually to AWS Regions.”
Read 2026-09-13 · official pricing · Report a correction
- Free Azure Services ↗
“Some are always free to all Azure customers, and some are free for 12 months to new customers only. [...] 12 months free services is available only to new customers who have not previously had an Azure account or received 12 months of free services.”
Read 2026-09-13 · official pricing · Report a correction
When the free offer ends
6 months after account creation; Free Tier credits expire 12 months after that date.
30 days.
Sources (2) →Sources ↓
- Amazon S3 Pricing ↗
“The free plan will be available for 6 months after account creation. [...] All Free Tier credits must be used within 12 months of your account creation date.”
Read 2026-09-13 · official pricing · Report a correction
- Azure Blob Storage pricing ↗
“Get free cloud services and a $200 credit to explore Azure for 30 days.”
Read 2026-09-13 · official pricing · Report a correction
Pricing model
- Amazon S3
- Per region and per storage class, with storage, requests, retrievals, data transfer and management features each metered separately. AWS states there is no minimum charge, and bills storage in binary gigabytes — 1 GB is 2^30 bytes, not 10^9.
- Azure Blob Storage
- Per region, per redundancy and per access tier, with storage, operations and egress metered separately; no plans and no bundles.
Sources (2) →Sources ↓
- S3 Pricing — AWS ↗
“Pay only for what you use. There is no minimum charge. Amazon S3 cost components are storage pricing, request and data retrieval pricing, data transfer and transfer acceleration pricing, data management and insights feature pricing, replication pricing, and transform and query feature pricing. [...] Amazon S3 storage usage is calculated in binary gigabytes (GB), where 1 GB is 230 bytes.”
Read 2026-09-06 · official docs · Report a correction
- Azure Retail Prices API — Blob Storage Hot LRS, East US ↗
“{"currencyCode":"USD","tierMinimumUnits":0.0,"retailPrice":0.0208,"unitPrice":0.0208,"armRegionName":"eastus","location":"US East","effectiveStartDate":"2017-02-03T00:00:00Z","meterId":"272492b3-1c92-4a5f-bee9-52a8e10ca514","meterName":"Hot LRS Data Stored"," [...] {"currencyCode":"USD","tierMinimumUnits":0.0,"retailPrice":0.05,"unitPrice":0.05,"armRegionName":"eastus","location":"US East","effectiveStartDate":"2016-11-01T00:00:00Z","meterId":"14854f12-8d37-4299-842a-b0f2df82a305","meterName":"Hot LRS Write Operations","”
Read 2026-09-13 · official pricing · Report a correction
Egress over allowance
- Amazon S3
- $0.09 per GB for the first 10 TB a month out to the internet, after a free 100 GB aggregated globally. It falls to $0.085 above 10 TB, $0.07 above 50 TB and $0.05 above 150 TB. This is AWS's outbound data transfer rate rather than an S3-specific one — the charge that R2, Wasabi and Tigris do not levy at all.
- Azure Blob Storage
- First 100 GB a month free, then $0.087 per GB over Microsoft's global egress meter, falling to $0.083 above 10 TB.
Sources (2) →Sources ↓
- AWS Price List API — AWSDataTransfer, us-east-1 ↗
“"$0 for 100GB of data transfer out to the internet, aggregated globally" [...] "$0.090 per GB - first 10 TB / month data transfer out beyond the global free tier" [...] "$0.085 per GB - next 40 TB / month" [...] "$0.070 per GB - next 100 TB / month" [...] "$0.050 per GB - greater than 150 TB / month"”
Read 2026-09-06 · official pricing · Report a correction
- Azure Retail Prices API — Bandwidth, East US ↗
“{"currencyCode":"USD","tierMinimumUnits":0.0,"retailPrice":0.0,"unitPrice":0.0,"armRegionName":"eastus","location":"US East","effectiveStartDate":"2022-05-01T00:00:00Z","meterId":"9995d93a-7d35-4d3f-9c69-7a7fea447ef4","meterName":"Standard Data Transfer Out"," [...] {"currencyCode":"USD","tierMinimumUnits":0.0,"retailPrice":0.0,"unitPrice":0.0,"armRegionName":"eastus","location":"US East","effectiveStartDate":"2022-05-01T00:00:00Z","meterId":"9995d93a-7d35-4d3f-9c69-7a7fea447ef4","meterName":"Standard Data Transfer Out","”
Read 2026-09-13 · official pricing · Report a correction
Storage (entry plan)
- Amazon S3
- None. S3 has no plans and no included storage — AWS states there is no minimum charge and you pay only for what you use, billed per GB-month from the first byte. New accounts get AWS Free Tier credits ($100 immediately, up to $200 over six months) which are spendable credit rather than a standing storage allowance.
- Azure Blob Storage
- None. Azure Blob has no plans and no free storage band: the Hot LRS meter is charged from the first GB.
Sources (2) →Sources ↓
- Amazon S3 Pricing ↗
“Pay only for what you use. There is no minimum charge. Amazon S3 cost components are storage pricing, request and data retrieval pricing, data transfer and transfer acceleration pricing”
Read 2026-09-07 · official pricing · Report a correction
- Azure Retail Prices API — Blob Storage Hot LRS, East US ↗
“{"currencyCode":"USD","tierMinimumUnits":0.0,"retailPrice":0.0208,"unitPrice":0.0208,"armRegionName":"eastus","location":"US East","effectiveStartDate":"2017-02-03T00:00:00Z","meterId":"272492b3-1c92-4a5f-bee9-52a8e10ca514","meterName":"Hot LRS Data Stored"," [...] {"currencyCode":"USD","tierMinimumUnits":0.0,"retailPrice":0.0208,"unitPrice":0.0208,"armRegionName":"eastus","location":"US East","effectiveStartDate":"2017-02-03T00:00:00Z","meterId":"272492b3-1c92-4a5f-bee9-52a8e10ca514","meterName":"Hot LRS Data Stored","”
Read 2026-09-13 · official pricing · Report a correction
Uptime SLA
- Amazon S3
- 99.9% for S3 Standard, Express One Zone and the Glacier retrieval classes; 99.0% for Intelligent-Tiering, Standard-Infrequent Access, One Zone-IA and Glacier Instant Retrieval.
- Azure Blob Storage
- Not published as a web page. Microsoft consolidated its per-service SLAs into one downloadable document covering Azure, Dynamics 365, Office 365 and Intune; the former azure.microsoft.com SLA URLs now redirect to its licensing viewer.
Sources (2) →Sources ↓
- Amazon S3 Service Level Agreement ↗
“For requests to S3 Standard, S3 Express One Zone, S3 Glacier Flexible Retrieval, S3 Glacier Deep Archive, and all other requests not specified below: Monthly Uptime Percentage Service Credit Percentage Less than 99.9% but greater than or equal to 99.0% 10% [...] For requests to S3 Intelligent-Tiering, S3 Standard-Infrequent Access, S3 One Zone-Infrequent Access, and S3 Glacier Instant Retrieval: Monthly Uptime Percentage Service Credit Percentage Less than 99.0% but greater than or equal to 98.0% 10%”
Read 2026-09-14 · official site · Report a correction
- Service Level Agreements (SLA) for Online Services — Microsoft ↗
“the service level agreements (sla) describe microsoft's commitments for uptime and connectivity for microsoft online services. the current and archived editions of the sla are available for download and they cover azure, dynamics 365, office 365, and intune.”
Read 2026-09-15 · official site · Report a correction
Storage price
- Amazon S3
- $0.023 per GB-month for S3 Standard, first 50 TB, in us-east-1. S3 prices vary by region; this and every other S3 figure on the site is that region.
- Azure Blob Storage
- $0.0208 per GB-month for Hot LRS in East US, falling to $0.019968 above 50 TB and $0.019136 above 500 TB.
Sources (2) →Sources ↓
- AWS Price List API — AmazonS3, us-east-1 ↗
“"description": "$0.023 per GB - first 50 TB / month of storage used", "pricePerUnit": {"USD": "0.0230000000"}, "unit": "GB-Mo", "beginRange": "0", "endRange": "51200"”
Read 2026-09-06 · official pricing · Report a correction
- Azure Retail Prices API — Blob Storage Hot LRS, East US ↗
“{"currencyCode":"USD","tierMinimumUnits":0.0,"retailPrice":0.0208,"unitPrice":0.0208,"armRegionName":"eastus","location":"US East","effectiveStartDate":"2017-02-03T00:00:00Z","meterId":"272492b3-1c92-4a5f-bee9-52a8e10ca514","meterName":"Hot LRS Data Stored"," [...] {"currencyCode":"USD","tierMinimumUnits":0.0,"retailPrice":0.0208,"unitPrice":0.0208,"armRegionName":"eastus","location":"US East","effectiveStartDate":"2017-02-03T00:00:00Z","meterId":"272492b3-1c92-4a5f-bee9-52a8e10ca514","meterName":"Hot LRS Data Stored"," [...] {"currencyCode":"USD","tierMinimumUnits":0.0,"retailPrice":0.0208,"unitPrice":0.0208,"armRegionName":"eastus","location":"US East","effectiveStartDate":"2017-02-03T00:00:00Z","meterId":"272492b3-1c92-4a5f-bee9-52a8e10ca514","meterName":"Hot LRS Data Stored","”
Read 2026-09-13 · official pricing · Report a correction
Operations price
- Amazon S3
- $0.005 per 1,000 PUT, COPY, POST and LIST requests, and $0.004 per 10,000 GET and all other requests, in us-east-1. DELETE and CANCEL are free.
- Azure Blob Storage
- $0.05 per 10,000 write operations and $0.004 per 10,000 reads on Hot LRS in East US.
Sources (2) →Sources ↓
- AWS Price List API — AmazonS3, us-east-1 ↗
“"description": "$0.005 per 1,000 PUT, COPY, POST, or LIST requests" [...] "description": "$0.004 per 10,000 GET and all other requests" [...] DELETE and CANCEL requests are free.”
Read 2026-09-06 · official pricing · Report a correction
- Azure Retail Prices API — Blob Storage Hot LRS, East US ↗
“{"currencyCode":"USD","tierMinimumUnits":0.0,"retailPrice":0.05,"unitPrice":0.05,"armRegionName":"eastus","location":"US East","effectiveStartDate":"2016-11-01T00:00:00Z","meterId":"14854f12-8d37-4299-842a-b0f2df82a305","meterName":"Hot LRS Write Operations"," [...] {"currencyCode":"USD","tierMinimumUnits":0.0,"retailPrice":0.004,"unitPrice":0.004,"armRegionName":"eastus","location":"US East","effectiveStartDate":"2016-11-01T00:00:00Z","meterId":"c5248cf8-ecba-4807-9304-6a8f14b5805a","meterName":"Hot Read Operations","”
Read 2026-09-13 · official pricing · Report a correction
Minimum storage duration
None on S3 Standard. 30 days on Standard-IA and One Zone-IA, 90 days on Glacier Instant and Flexible Retrieval, 180 days on Glacier Deep Archive, each with a pro-rated charge for early deletion.
None on Hot. Cool carries a 30-day minimum, Cold 90 days and Archive 180 days — the longest early-deletion window of any provider here, and three times S3's 90-day Glacier figure.
Sources (2) →Sources ↓
- S3 Pricing — AWS ↗
“S3 Standard-IA, and S3 One Zone-IA storage are charged for a minimum storage duration of 30 days [...] Objects that are archived to S3 Glacier Instant Retrieval and S3 Glacier Flexible Retrieval are charged for a minimum storage duration of 90 days, and S3 Glacier Deep Archive has a minimum storage duration of 180 days.”
Read 2026-09-06 · official docs · Report a correction
- Access tiers for blob data — Microsoft Learn ↗
“Data in the cool tier should be stored for a minimum of 30 days. [...] Data in the cold tier should be stored for a minimum of 90 days. [...] Data in the archive tier should be stored for a minimum of 180 days.”
Read 2026-09-07 · official docs · Report a correction
SOC 2
- Amazon S3
- Listed as SOC-compliant on AWS's own compliance scope page.
- Azure Blob Storage
- Listed among Azure's compliance offerings (SOC 1, SOC 2, SOC 3) on Microsoft's own compliance documentation — a platform-wide list, not scoped to this specific service.
Sources (2) →Sources ↓
- AWS Services in Scope — SOC ↗
“This webpage provides a list of AWS Services in Scope of AWS assurance programs. [...] Amazon Simple Storage Service (S3) ✓ Amazon Simple Workflow Service (SWF) ✓ Amazon Textract ✓”
Read 2026-09-13 · official site · Report a correction
- Azure compliance documentation — Microsoft Learn ↗
“Compliance offerings [...] SOC 1 SOC 2 SOC 3”
Read 2026-09-12 · official site · Report a correction
ISO 27001
- Amazon S3
- Covered under AWS's account-wide ISO/IEC 27001:2022 certification — not scoped per-service the way SOC, HIPAA and PCI DSS are on AWS's own site.
- Azure Blob Storage
- Listed among Azure's compliance offerings (ISO 27001) on Microsoft's own compliance documentation — a platform-wide list, not scoped to this specific service.
Sources (2) →Sources ↓
- ISO/IEC 27001:2022 Compliance — AWS ↗
“AWS has certification for compliance with ISO/IEC 27001:2022, 27017:2015, and 27018:2019. These certifications are performed by independent third-party auditors.”
Read 2026-09-12 · official site · Report a correction
- Azure compliance documentation — Microsoft Learn ↗
“Compliance offerings [...] ISO 27001 ISO 27017 ISO 27018”
Read 2026-09-12 · official site · Report a correction
HIPAA
- Amazon S3
- Listed as a HIPAA-eligible service on AWS's own reference page.
- Azure Blob Storage
- Listed among Azure's compliance offerings (HIPAA) on Microsoft's own compliance documentation — a platform-wide list, not scoped to this specific service.
Sources (2) →Sources ↓
- HIPAA Eligible Services Reference — AWS ↗
“The services listed below are eligible to create, receive, process, maintain, or transmit electronic protected health information (ePHI). [...] Amazon Simple Storage Service (S3) Amazon Simple Workflow Service (SWF) AWS Snowball AWS”
Read 2026-09-13 · official site · Report a correction
- Azure compliance documentation — Microsoft Learn ↗
“Healthcare and life sciences [...] HIPAA (US)”
Read 2026-09-12 · official site · Report a correction
PCI DSS
- Amazon S3
- Listed as PCI DSS-compliant on AWS's own compliance scope page.
- Azure Blob Storage
- Listed among Azure's compliance offerings (PCI DSS) on Microsoft's own compliance documentation — a platform-wide list, not scoped to this specific service.
Sources (2) →Sources ↓
- AWS Services in Scope — PCI DSS ↗
“This webpage provides a list of AWS Services in Scope of AWS assurance programs. [...] Amazon Simple Storage Service (S3) ✓ ✓ Amazon Simple Workflow Service (SWF) ✓ ✓ Amazon”
Read 2026-09-13 · official site · Report a correction
- Azure compliance documentation — Microsoft Learn ↗
“Financial services [...] PCI 3DS PCI DSS”
Read 2026-09-12 · official site · Report a correction
When these numbers change, hear about it. Sources are re-checked monthly; a repricing goes out as a short note.
Documented by only one.
These criteria are published by one provider and not the other. An absence here means we have not found a source, not that the feature is missing — except where we say we read the other provider's own page on a given date and it does not state it. Those rows lean, and the provider can correct them with a link.
Questions this comparison answers.
Free tier: Amazon S3 or Azure Blob Storage?
Amazon S3: Yes
Azure Blob Storage: No
Egress over allowance: Amazon S3 or Azure Blob Storage?
Amazon S3: $0.09 per GB for the first 10 TB a month out to the internet, after a free 100 GB aggregated globally. It falls to $0.085 above 10 TB, $0.07 above 50 TB and $0.05 above 150 TB. This is AWS's outbound data transfer rate rather than an S3-specific one — the charge that R2, Wasabi and Tigris do not levy at all.
Azure Blob Storage: First 100 GB a month free, then $0.087 per GB over Microsoft's global egress meter, falling to $0.083 above 10 TB.
Storage (entry plan): Amazon S3 or Azure Blob Storage?
Amazon S3: None. S3 has no plans and no included storage — AWS states there is no minimum charge and you pay only for what you use, billed per GB-month from the first byte. New accounts get AWS Free Tier credits ($100 immediately, up to $200 over six months) which are spendable credit rather than a standing storage allowance.
Azure Blob Storage: None. Azure Blob has no plans and no free storage band: the Hot LRS meter is charged from the first GB.
Should I choose Amazon S3 or Azure Blob Storage?
Pick Amazon S3 if Workloads already inside AWS, where keeping data in the same region as the compute avoids the transfer charges that dominate an object storage bill.
Pick Azure Blob Storage if Workloads already on Azure, where keeping storage in the same region as the compute avoids the bandwidth charge that dominates an object storage bill.
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