Adjusting the Xcode iPhone simulator scale and size [duplicate]

With Xcode 9 - Simulator, you can pick & drag any corner of simulator to resize it and set according to your requirement.

Look at this snapshot.

Note: With Xcode 9.1+, Simulator scale options are changed.

Keyboard short-keys:
According to Xcode 9.1+

Physical Size       ⌘ 1      command + 1Pixel Accurate      ⌘ 2      command + 2

According to Xcode 9

50% Scale           ⌘ 1      command + 1100% Scale          ⌘ 2      command + 2200% Scale          ⌘ 3      command + 3

Simulator scale options from Xcode Menu:

Xcode 9.1+:
Menubar ▶ Window ▶ "Here, options available change simulator scale" (Physical Size & Pixel Accurate)

Pixel Accurate: Resizes your simulator to actual (Physical) device's pixels, if your mac system display screen size (pixel) supports that much high resolution, else this option will remain disabled.

Tip: rotate simulator ( ⌘ + ← or ⌘ + → ), if Pixel Accurate is disabled. It may be enabled (if it fits to screen) in landscape.

Xcode 9.0
Menubar ▶ Window ▶ Scale ▶ "Here, options available change simulator scale"

Tip: How do you get screen shot with 100% (a scale with actual device size) that can be uploaded on AppStore?

Disable 'Optimize Rendering for Window scale' from Debug menu, before you take a screen shot (See here: How to take screenshots in the iOS simulator)

There is an option

Menubar ▶ Debug ▶ Disable "Optimize Rendering for Window scale"

Here is Apple's document: Resize a simulator window

You can't have 1:1 ratio.

However you can scale it from the iOS Simulator > Window > Scale menu.

Check this Image… You can change your simulator size from here

or press CMD+1, CMD+2 or CMD+3