Not understand iPhone resolution

Hello

I made a simple web app 800x600px on my browsers is all good but when I show this on my iPhone 6(s) plus (IOS9) I cannot see all of my 800x600px.

The resolution from the iPhone is ~2000px width what is the problem I cannot see 800px width?

Is an Web App not an IOS App.

Thanks for Ideas.
Roger

Things on iPhone render in points, not pixels. An iPhone 6 Plus is 414 x 736 points.

This page has some graphics that explain this pretty well:
http://www.paintcodeapp.com/news/iphone-6-screens-demystified

Many thanks Paul.