Serverless computing is gaining a lot of attention.  To some, it is the answer to providing the most cost effective computing services the cloud has to offer. Amazon's serverless product, AWS Lambda, is a top choice when moving to a serverless systems architecture. But just how much are you going to spend?  What does AWS Lambda cost?

Detail Breakdown

The first thing to understand about AWS Lambda cost is that you get a large chunk of it free every month.  The “Free Tier” as it is called is used up first before you are billed for any AWS Lambda cost.

The Free Tier thresholds are:

  • 1 Million requests per month
  • 400,000 GB seconds of compute time per month

The first is pretty straight forward.  Any request to AWS Lambda, whether triggered through events, API interactions, or manually through the test console is counted as a request.  Until you reach 1 million requests in a month, this component of AWS Lambda cost is free!

After you exceed the 1 million request threshold, you will be charged $0.20 per each additional 1 million requests.  So a total of 2 million requests in a month would cost $0.20 and 3 million would cost $0.40.

The second, GB seconds, takes some explaining.

What is an AWS Lambda GB Second?

Amazon measures a GB second in terms of memory utilization and duration.  AWS Lambda lets you configure different levels of memory to allocate to your Lambda functions ranging from 128 MB to 3008 MB.

To the amount of GB seconds you've consumed with a particular operation you multiply the number of seconds the operation took to complete by the amount of memory utilized and divide by 1024.

Let's look at a example to illustrate

GB Second Example

Let's say you have 512 MB of memory configured for your AWS Lambda operation.  A single request takes two seconds to complete.  You would multiply two by 512 to reach 1024.  You would then divide that by 1024 and arrive at 1 GB Second.

You now have 399,999 GB seconds remaining in the Free Tier before you begin to incur AWS Lambda cost for GB compute seconds.

But what does a GB second in AWS Lambda cost once you've crossed the free threshold?

AWS Lambda GB Second Pricing

The memory level you allocate to your AWS Lambda function determines the price per GB second.  At 128 MB you will pay $0.00000208 per 1 second and at 3008 MB you will pay $0.00004897 per 1 second.

So in our example of a 512 MB function the price is $0.00000834 per GB second.  At that price 1 million GB seconds of compute time would cost $8.34.

That's over eleven days.

Are there any other Costs?

AWS Lambda Cost accounts for the compute time involved within your Lambda function.  If you are utilizing services like S3 storage you will incur cost for those additional services.

But!  You will not be incurring infrastructure costs of on premise networking, servers, or utilities to support your computing systems.  Also, the systems administration overhead and procurement overhead for your technology will be drastically reduced.

Next Steps

Go, take a look at AWS Lambda.  Experiment with your own serverless applications.  Determine if the reduced infrastructure and administrative cost make a significant impact and if your architecture fits with AWS Lambda.

You can experiment in the Free Tier and learn what you need to know and if AWS Lambda is the right strategic direction for you.

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— Nat