Usually, if you want to use infrastructure to run your website in a cloud, you need to pre-pay and guesstimate your needs.

Cloud-hosting provider ElasticHosts is making matters easier today, by letting applications automatically scale out to match usage.

As a result, with ElasticHosts’ new Elastic Containers, companies can pay less money because they don’t need to over-provision. So every 15 minutes, companies are charged by how much they use, not how much they’re set up to use.

Highly configurable Infrastructure-as-a-Service (IaaS) clouds like Amazon Web Services and Google Compute Engine have been slashing prices and offering auto-scaling capabilities, but they still require companies to project their usage ahead of time. ElasticHosts, which offers fewer cloud services than those vendors, can meet the needs of individual developers and some businesses.

The advancement challenges basic cloud infrastructure providers like DigitalOcean and Linode, as they target small and medium-sized businesses just like ElasticHosts.

But still, the new pricing model could be appealing to current Amazon customers.

“The key thing about the usage is Amazon would say that they charge on usage, and they charge every hour. But they charge for the size of the server you’re running, not the use of the server you’re running,” ElasticHosts chief executive Richard Davies said in an interview with VentureBeat.

One enabling factor here: Rather than divide up individual cloud servers with virtual machines to handle application code, ElasticHosts uses Linux containers, which can be more lightweight. Docker has realized this, and the approach is becoming more pervasive all the time, with ElasticHosts being the latest vendor to try to take advantage of the technology.

As a result, ElasticHosts can offer auto-scaling and billing based on usage “in a way that no virtualized server provider will be able to,” Davies said.

London-based ElasticHosts started in 2008 and claims thousands of customers. It sounds like the Elastic Container addition could make ElasticHosts more popular.