It's Not "All You Can Eat"
The "Free Tier" is not a single switch you flip when you sign up. It is a collection of specific discounts applied to specific services, with specific limits, that expire on specific schedules. Treating it as a blanket guarantee is the most common and most expensive mistake beginners make.
There are three distinct categories of "Free":
1. Always Free
These never expire, regardless of how long your account has been open.
- AWS Lambda: 1 million requests/month and 400,000 GB-seconds of compute time.
- DynamoDB: 25 GB of storage and 25 write/read capacity units.
- CloudWatch: 10 custom metrics and 10 alarms.
Goal: You can build and run small serverless applications indefinitely at $0.
2. 12 Months Free
These start the clock the moment you create your account and expire exactly 12 months later — not when you first use the service.
- EC2: 750 hours/month of
t2.microort3.micro(Linux or Windows). - S3: 5 GB of standard storage.
- RDS: 750 hours/month of
db.t2.microordb.t3.micro.
Trap: 750 hours/month sounds like a lot, but one instance running 24/7 consumes exactly 720–744 hours. If you run two t2.micro instances simultaneously, you exhaust the free tier in 15 days and pay for the rest of the month. In Month 13, you pay full price from the first second.
3. Short-Term Trials
These last for a fixed window — days or months — from the moment you first activate the service.
- Amazon Redshift: 2 months of a
dc2.largenode. - SageMaker: 2 months of Studio notebook usage.
Trap: These are expensive enterprise tools. A Redshift dc2.large node costs roughly $0.25/hour. If you forget to delete it after the trial ends, you are paying $180/month for a data warehouse you are not using.
The Region and Instance Type Rules
The Free Tier applies only to specific instance types in specific regions. This is not always clearly communicated during the launch wizard.
| Action | Cost |
|---|---|
t2.micro in us-east-1 |
Free (within limits) |
t3.micro in eu-west-1 |
Free (within limits) |
t2.large anywhere |
Paid immediately |
t2.micro in ap-southeast-2 |
Free (within limits) |
| Any GPU instance anywhere | Paid immediately |
Practical rule: Before launching anything, search "[service name] free tier limits" in the AWS documentation. Verify the exact instance type and region eligibility. Do not guess.
Interviewers sometimes ask: "How does the AWS Free Tier work?" A weak answer is "You get free services for a year." A strong answer distinguishes the three categories, explains that the 12-month clock starts at account creation (not first use), and notes that running two Free Tier–eligible instances simultaneously halves your free hours. This shows you understand the billing model, not just the marketing copy.