Azure · Free tool

Azure Blob storage tier cost calculator

Plug in storage size, retention, transaction volume, and retrieval. See Hot, Cool, Cold, and Archive side by side with the minimum-duration penalty already applied. The cheapest tier for archival data is usually wrong for warm data, and the math is what shows you which is which.

Cheapest tier for this profile

Hot

$0/mo · $0/year

Tier	Storage	Transactions	Retrieval	Penalty	Monthly

Penalty column shows minimum-duration billing if your retention is shorter than the tier minimum (30 days Cool, 90 days Cold, 180 days Archive). Empty means retention covers the minimum.

When the cheap tier is the wrong tier

Three patterns show up over and over in audits. First, lifecycle policies that drop everything to Archive after 30 days, then a security review pulls the whole bucket and the rehydration cost is a five-figure surprise. Second, backup tools writing to Cool with a 14-day retention. The 30-day minimum means you pay 30 days of storage for every 14 days of actual data. Third, application logs on Hot tier when 95% of reads come in the first 7 days. Move them to Cool after 30 and the storage line drops by 45%.

The right tier depends on access pattern, retention, and how often you need data back within minutes versus hours. The calculator covers the math; we cover the operational details as part of the 14-day audit.

Frequently asked

Which blob tier is cheapest?

Archive at $0.00099 per GB-month, but only if you keep the data 180 days or more and almost never read it. Rehydration takes hours and costs around $0.022 per GB. For data you might need within minutes, Cold tier at $0.0036 per GB-month is usually the right floor.
How does the minimum duration penalty work?

Cool bills 30 days minimum, Cold bills 90 days minimum, Archive bills 180 days minimum. If you delete or change tier before the minimum, you still pay storage to the minimum. A 14-day backup on Cool tier pays roughly twice the storage you actually use.
When is Cold tier the right choice over Cool?

Cold is roughly a third of the storage price of Cool ($0.0036 vs $0.01 per GB-month) but charges 3x more on retrieval ($0.03 vs $0.01 per GB) and has a 90-day minimum vs 30. The break-even depends on read percentage. Below about 5% of data read per month and retention over 90 days, Cold wins. Above that, Cool wins.
Does redundancy choice change the math much?

LRS is the cheapest. ZRS adds about 25%, GRS roughly doubles, GZRS sits around 2.5x. The relative ranking between tiers stays the same; the absolute numbers move. The calculator below uses LRS to keep comparisons honest. Multiply the storage line by your redundancy factor for an approximation.