How does Amazon S3 Calculate Storage Used

by Steve


The pricing model for Amazon’s S3 storage is like a math problem with too many variables.  There is storage used, bandwidth used, puts and gets and surely more that get poured into the simmering pot that is your S3 billing charge.  This post will be the first in a series of short posts explaining how the different components are charged for by Amazon.

Storage Used

In simple terms Amazon averages out the storage you have in use, on a daily basis and charges you for the storage used at the end of the month.  The cleverly call this average “TimedStorage-ByteHrs”.

Here’s an example from their website:

Storage Example:
Assume you store 100GB (107,374,182,400 bytes) of standard Amazon S3 storage data in your bucket for 15 days in March, and 100TB (109,951,162,777,600 bytes) of standard Amazon S3 storage data for the final 16 days in March.

At the end of March, you would have the following usage in Byte-Hours:
Total Byte-Hour usage
= [107,374,182,400 bytes x 15 days x (24 hours / day)] + [109,951,162,777,600 bytes x 16 days x (24 hours / day)] = 42,259,901,212,262,400 Byte-Hours.

Let’s convert this to GB-Months:
42,259,901,212,262,400 Byte-Hours x (1 GB / 1,073,741,824 bytes) x (1 month / 744 hours) = 52,900 GB-Months

This usage volume crosses three different volume tiers. The monthly storage price is calculated below assuming the data is stored in the US Standard Region:
1 TB Tier: 1024GB x $0.140 = $143.36
1 TB to 50 TB Tier: 50,176 GB (49×1024) x $0.125 = $6,272.00
50 TB to 450 TB Tier: 1,700 GB (remainder) x $0.110 = $187.00

Total Storage Fee = $143.36 + $6,272.00 + $187.00 = $6,602.36

GOOD GRIEF – Who writes this stuff for them?

Here’s another way of looking at it:

They take measurements of your storage used throughout the month, and charge you based on Actual storage used.  The charges begin at 14 cents per GB and drop from there based on volume.

Here’s a simple example – you have 6 GB of data and that data remains constant throughout the month.  You’ll be charged 6 x .14 or .84 (84 cents) for the storage portion of your bill.

If you keep your storage under 5 GB there is no charge for the storage during your accounts first year.

The next post will deal with data transfer.






{ 4 comments… read them below or add one }

Kirti December 13, 2011 at 1:46 am

Nice Article..
Its always nice to know how much people are interested in Amazon S3 and its services.
You can try my very own tool bucket explorer Try to use the services of S3 and manage data at S3…


Steve December 13, 2011 at 10:42 am

Thanks – It looks like your company has assembled quite a team for Bucket Explorer, which is a very well regarded program. Thanks for stopping by. For those considering Bucket Explore it is a great program if you’re looking for a paid product.


Danny Briere March 22, 2012 at 7:58 am

Great post! Do you know what they do about the following? We need to ‘transit’ S3 for the creation of uploads to YouTube. So we will dump a 2GB file on S3 for about 5 mins., and then delete it. If we did this 100 times a day, would they charge us for 200GB, for the amount that is there when they check (which would be n x 2GB where n happens to be the number of transits going on at the time, so n=0…100 conceivably)?


Steve March 22, 2012 at 8:29 am

Thanks – In the case you describe there would probably be no storage cost but there would be bandwidth costs, which can add up. The constantly track bandwidth used (see this post for more information on how they calculate it)

For storage my understanding is that they charge for bytes used per hour so I’m sure they have a way of tracking how much actual storage your using but in your example that number is fairly small – assuming you really do only keep the files on their storage for 5 minutes. If so the transfer time would exceed the length of time you’re storing the file so at any given time you’d only be storing a single 2 GB file.


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