Can You Reduce Your AWS Bill?
Running a server on AWS does not have one fixed price. Depending on how you purchase and use it, the exact same server can cost dramatically different amounts — in some cases up to 90% less.
Understanding which option fits which situation helps you save money in real life and score well on the exam.
---
Think of EC2 Purchase Options as Types of Transportation
Imagine five ways to get around town.
On-Demand is a taxi. Hop in any time, pay for exactly how far you go. Most expensive, but no contracts or commitments required.
Reserved Instances are a monthly bus pass with a 1 or 3 year commitment. You agree upfront to use the bus for a year, but the per-trip cost drops dramatically.
Savings Plans are a more flexible version of a transit card. Like Reserved Instances, you commit to spending a certain amount per hour over 1 or 3 years. But you are not locked into a specific instance type or region.
Spot Instances are standby airline tickets. The airline sells empty seats at huge discounts. But if a paying full-price customer shows up, your seat gets cancelled with 2 minutes notice. Up to 90% cheaper, but interruptible.
Dedicated Hosts are buying your own car instead of renting. You get an entire physical server to yourself. Mainly used when companies need to bring their existing software licenses with them (called BYOL — Bring Your Own License).
---
Purchase Options at a Glance
| Option | Discount | Commitment | Best Situation | |--------|----------|------------|----------------| | On-Demand | None | None | Short tests, unpredictable traffic spikes | | Reserved Instances | Up to 72% | 1 or 3 years | Production servers running 24 hours a day | | Savings Plans | Up to 72% | 1 or 3 years | Same as Reserved but more flexible | | Spot Instances | Up to 90% | None | Batch jobs or analysis that can be interrupted | | Dedicated Hosts | Varies | Optional | Bringing existing licenses (BYOL), compliance needs |
!EC2 purchase options compared
When Should You Use Spot Instances?
Spot Instances let you use AWS's unused server capacity at a steep discount. But when AWS needs that capacity back, they take it with only 2 minutes of warning.
This makes Spot Instances suitable only for interruptible work. Good examples: encoding videos, large-scale data analysis, and automated software testing pipelines (CI/CD). Bad examples: web servers customers connect to, payment processing systems, and databases. Never put critical systems on Spot Instances.
---
AWS Free Tier — Try AWS at No Cost
AWS offers free usage for people who are just getting started.
For the first 12 months after signing up, you can use EC2 t2.micro (or t3.micro) instances up to 750 hours per month and S3 up to 5 GB — both at no charge.
Some services stay free forever, regardless of how long you have had your account. Lambda gives you 1 million requests per month free. DynamoDB gives you 25 GB of storage free. These never expire.
---
Understanding Data Transfer Costs
Data transfer fees can surprise people on their first AWS bill. Here are the basics:
Data coming into AWS from the internet (inbound) is free. Data leaving AWS to the internet (outbound) costs money. Data moving within the same Availability Zone is free. Data moving between different Availability Zones in the same region costs a small fee.
---
Exam Quick Reference
"Pay as you go, no commitment, most expensive" — On-Demand "1-3 year commitment, up to 72% off, fixed instance type" — Reserved Instances "1-3 year commitment, up to 72% off, flexible usage" — Savings Plans "Up to 90% off, can be interrupted at any time" — Spot Instances "Use existing software licenses as-is (BYOL)" — Dedicated Hosts "Inbound data transfer" — Free "Lambda 1 million requests/month, DynamoDB 25 GB" — Always Free Tier Spot Instances should only be used for work that can tolerate interruption