Using to Optimize EC2 Costs

We created a while ago to make it easier to decide which EC2 pricing option to use. Since then, we’ve gotten some questions on how to use it most effectively. To clarify its usage, I’ll walk through a couple of examples.

First generation Standard Medium instance, 100% utilization, 8 months

Hypothetical scenario: continuous integration box for a medium-term project (8 months). Since it’s a CI box for your hardworking global team, it needs to be running 24/7.

In the controls at the top, configure your desired region, and then select “Standard 1st gen” (since this is an m1 instance) and Medium. We’ll leave days at 365 since 8 months is close enough to the default.


8 months is about 244 days, and surprisingly enough the 3 year light utilization reserved instance turns out to be the cheapest.


However, 1 year light, 1 year medium, and 3 year light are all almost exactly the same cost. 1 year light is the cheapest before 8 months, while 1 year medium is the cheapest after 8 months. If it was up to me, I’d pick the 1 year medium in case an 8 month project becomes a 10 month project, but the cost of all 3 is fairly close. Then again, if it turns out to be a 14 month project, the 3 year light would be the best choice.

Second generation Standard XL instance, 60% utilization, 1.5 years

Hypothetical scenario: server used to run reports during business hours.

I’ve set up this graph at 730 days and 60% utilization, and the cursor highlight is at 1.5 years (548 days).


This time, with fractional utilization being taken into account, the heavy instances are nowhere near competitive price-wise, which makes sense. The 3 year light is the definite winner this time.

High CPU XL instance, 20% utilization, 2 months

Hypothetical scenario: short-term need for data processing once or twice a week.


An on demand instance is dramatically cheaper than the other options. Lest the previous two examples make it appear that reserved instances are the way to go, this should serve as a reminder that a lot of the value that EC2 offers is in cost-effectively handling occasional workloads.

Posted by Marshall Pierce

Marshall specializes in highly tuned and immensely scalable web and mobile applications. Experienced in front-end web and iOS development, he constantly pushes the boundaries of the latest browsers and mobile platforms. He splits his time with back-end development, where he is considered a domain expert in Java concurrency, distributed systems, systems design, and network security. Prior to co-founding Palomino Labs, Marshall was director of software development at Ness Computing where he led their initial launch. Before Ness, Marshall was a senior software developer at, where he built the best-in-class integration with

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