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Amazon S3 vs Backblaze B2

SEPT 2026 audit

A comparison of Amazon S3 and Backblaze B2 built from values read directly from each provider's own documentation, with the source recorded against every figure.

Reviewed by Palash BagchiUpdated 19 criteria comparedSources last checked

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 Backblaze B2 if…

Bulk capacity where egress is predictable — free up to three times what you store each month, which covers most backup and archive patterns comfortably at $6.95 per terabyte.

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.
  • Backblaze B2: Egress is only free to that 3x ceiling. A bucket read far more often than its size, like a public media library, is the shape this pricing is not built for.

Neither quite fits? Every other option, ranked by iScore: Amazon S3 alternatives · Backblaze B2 alternatives

13 sourced criteria separate them — see where, with sources, below.

Visit Amazon S3 documentationVisit Backblaze B2 documentation

No affiliate links, sponsored placements or paid rankings appear on this site. Ordering follows the sourced data and the stated criteria.

01.

At a glance.

CriterionAmazon S3Backblaze B2
Pricing
Free tierYesYes
Kind of free offerIntroductory free tierFree tier
What the free plan includes100 GB a month of data transfer out to the internet, counted globally rather than per region. Storage itself is billed from the first byte.The first 10 GB of storage is always free, egress is free up to three times average monthly storage, and the first 2,500 Class D transactions each day are free.
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.Free up to three times your stored capacity each month on the $6.95/TB tier; unlimited free egress on the $15/TB tier. Egress beyond the 3x allowance is chargeable.
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.10 GB free, permanently — 'First 10GB storage is always free.' The statement is a row-level note on Backblaze's pricing-model table, so it applies to B2 storage rather than to one plan, and it is an ongoing allowance rather than the 'Start Free' trial the page advertises separately.
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.
Credits begin below 99.9% monthly user uptime. The SLA is per user account and covers B2 Cloud Storage and Computer Backup.
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.$6.95 per TB per month on B2 Overdrive; $15 per TB per month on the unlimited-egress tier
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.Transactions are not charged on the $6.95/TB tier. Backblaze notes that its published chart uses U.S. West rates and that competitor rates vary by region and volume.
Minimum storage durationNone 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. Backblaze states no minimum file size or storage duration fee on B2 Cloud Storage, so an object deleted an hour after upload is billed only for that hour.
S3-compatible APISupportedSupported
Compliance
SOC 2Listed as SOC-compliant on AWS's own compliance scope page.SOC 2 Type 2 compliant, audited by an independent third-party firm; the data centers Backblaze operates in are also SOC 2 compliant.
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.
Not a Backblaze organizational certification — Backblaze states it primarily operates in data centers that hold ISO 27001 certificates, a facility-level attestation rather than one covering Backblaze itself.
HIPAAListed as a HIPAA-eligible service on AWS's own reference page.A Business Associate Agreement is available on request for business customers who are Covered Entities under HIPAA.
GDPR / data residencyAWS customers can process personal data on all AWS services in compliance with GDPR, and choose the storage type and geographic region for their data.Adheres to GDPR and UK GDPR privacy policies; Data Processing Agreement addendums are available for EEA/EU and UK residents.
PCI DSS
Listed as PCI DSS-compliant on AWS's own compliance scope page.
Card processing is handled through Stripe, which combined with Backblaze's internal security controls contributes to PCI-DSS adherence — not a direct PCI-DSS certification of Backblaze's own storage platform.

Only criteria both providers publish appear here; a tinted cell marks a real difference. Criteria only one of them documents are listed below, and an absence there means we found no source — not that the feature is missing. How we source this.

The small bar above a value is inetGeek's own lean toward that side — computed from the same facts shown, never a number the provider published. See the picker below "The short answer" to weigh only the criteria you care about.

02.

Where they differ.

Kind of free offer

Amazon S3
Introductory free tier
Backblaze B2
Free tier
Sources (2) →

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.
Backblaze B2
The first 10 GB of storage is always free, egress is free up to three times average monthly storage, and the first 2,500 Class D transactions each day are free.
Sources (2) →

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.
Backblaze B2
Free up to three times your stored capacity each month on the $6.95/TB tier; unlimited free egress on the $15/TB tier. Egress beyond the 3x allowance is chargeable.
Sources (2) →
  • 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

  • Cloud Storage Pricing — Backblaze ↗

    “Free egress up to 3x storage [...] Free transactions [...] Unlimited free egress [...] B2 includes 750 TB of monthly egress in this scenario.”

    Read 2026-09-06 · 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.
Backblaze B2
10 GB free, permanently — 'First 10GB storage is always free.' The statement is a row-level note on Backblaze's pricing-model table, so it applies to B2 storage rather than to one plan, and it is an ongoing allowance rather than the 'Start Free' trial the page advertises separately.
Sources (2) →

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.

Backblaze B2

Credits begin below 99.9% monthly user uptime. The SLA is per user account and covers B2 Cloud Storage and Computer Backup.

Sources (2) →
  • 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

  • Backblaze Service Level Agreement ↗

    “monthly user uptime percentage user credit percentage >= 99.9% 0%”

    Read 2026-09-14 · 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.
Backblaze B2
$6.95 per TB per month on B2 Overdrive; $15 per TB per month on the unlimited-egress tier
Sources (2) →

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.
Backblaze B2
Transactions are not charged on the $6.95/TB tier. Backblaze notes that its published chart uses U.S. West rates and that competitor rates vary by region and volume.
Sources (2) →

Minimum storage duration

Amazon S3

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.

Backblaze B2

None. Backblaze states no minimum file size or storage duration fee on B2 Cloud Storage, so an object deleted an hour after upload is billed only for that hour.

Sources (2) →
  • 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

  • Pricing — Backblaze B2 Cloud Storage ↗

    “$6.95 / TB / mo [...] No minimum file size or storage duration fees Free egress up to 3x storage Free transactions”

    Read 2026-09-07 · official pricing · Report a correction

SOC 2

Amazon S3
Listed as SOC-compliant on AWS's own compliance scope page.
Backblaze B2
SOC 2 Type 2 compliant, audited by an independent third-party firm; the data centers Backblaze operates in are also SOC 2 compliant.
Sources (2) →

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.
Backblaze B2
Not a Backblaze organizational certification — Backblaze states it primarily operates in data centers that hold ISO 27001 certificates, a facility-level attestation rather than one covering Backblaze itself.
Sources (2) →

HIPAA

Amazon S3
Listed as a HIPAA-eligible service on AWS's own reference page.
Backblaze B2
A Business Associate Agreement is available on request for business customers who are Covered Entities under HIPAA.
Sources (2) →

GDPR / data residency

Amazon S3
AWS customers can process personal data on all AWS services in compliance with GDPR, and choose the storage type and geographic region for their data.
Backblaze B2
Adheres to GDPR and UK GDPR privacy policies; Data Processing Agreement addendums are available for EEA/EU and UK residents.
Sources (2) →
  • GDPR — Amazon Web Services ↗

    “AWS customers can use all AWS services to process personal data [...] in compliance with the GDPR. [...] Customers have control of their customer data. With AWS, customers can: Determine where their customer data will be stored, including the type of storage and geographic region of that storage.”

    Read 2026-09-12 · official site · Report a correction

  • Cloud Regulatory Compliance — Backblaze B2 ↗

    “Backblaze adheres to General Data Protection Regulation (GDPR) privacy policies. Data Processing Agreement Addendums (DPAs) for EEA/EU and UK residents are available for compliance standards.”

    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.
Backblaze B2
Card processing is handled through Stripe, which combined with Backblaze's internal security controls contributes to PCI-DSS adherence — not a direct PCI-DSS certification of Backblaze's own storage platform.
Sources (2) →

When these numbers change, hear about it. Sources are re-checked monthly; a repricing goes out as a short note.

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03.

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.

When the free offer endsAmazon S3: 6 months after account creation; Free Tier credits expire 12 months after that date.
Pricing modelAmazon 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.
Support on entry paid planBackblaze B2: Giga support with every subscription. Tera and Peta are paid add-ons bought per service.
Response time commitmentBackblaze B2: Target response for email support: one business day on Giga, the included plan; 4 business hours on Tera; 2 business hours on Peta. Email support runs 9am to 5pm Pacific.
04.

Questions this comparison answers.

Egress over allowance: Amazon S3 or Backblaze B2?

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.

Backblaze B2: Free up to three times your stored capacity each month on the $6.95/TB tier; unlimited free egress on the $15/TB tier. Egress beyond the 3x allowance is chargeable.

Storage (entry plan): Amazon S3 or Backblaze B2?

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.

Backblaze B2: 10 GB free, permanently — 'First 10GB storage is always free.' The statement is a row-level note on Backblaze's pricing-model table, so it applies to B2 storage rather than to one plan, and it is an ongoing allowance rather than the 'Start Free' trial the page advertises separately.

Should I choose Amazon S3 or Backblaze B2?

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 Backblaze B2 if Bulk capacity where egress is predictable — free up to three times what you store each month, which covers most backup and archive patterns comfortably at $6.95 per terabyte.

Provider pages

Amazon S3AWS object storage, priced per region — every figure here is us-east-1 (US East, N. Virginia) from the published price list.Backblaze B2S3-compatible object storage sold per terabyte, with free egress capped at a multiple of stored capacity.

Related comparisons

Amazon S3 vs Azure Blob StorageAmazon S3 vs Bunny StorageAmazon S3 vs TigrisAmazon S3 vs WasabiAzure Blob Storage vs Backblaze B2Backblaze B2 vs Bunny StorageBackblaze B2 vs StorjBackblaze B2 vs Tigris

Comments

Every page here is sourced and dated.