# What is a GB-second?

> Learn what a GB-second is in AWS Lambda, the metric that multiplies how long your function runs by the memory it uses to measure your serverless usage.

Author: [Flavio Copes](https://flaviocopes.com/about/) | Published: 2020-03-23 | Topics: [Web Platform](https://flaviocopes.com/tags/platform/) | Canonical: https://flaviocopes.com/what-is-a-gb-second/

[AWS Lambda](https://aws.amazon.com/lambda) measures your usage time with a metric called GB-second.

Every month you are given 1M free requests, and 400.000 GB-seconds.

GB-seconds are the number of seconds your function runs for, multiplied by the amount of RAM memory consumed.

It's a computed metric, calculated by multiplying two other metrics, and it's a reasonable way to measure how many resources your serverless functions consume, in relation to time and memory.