Need to measure sizes and distances without Photoshop? Try Avocode
No need to buy or install Photoshop. Open and export assets from layered Photoshop designs on Mac, Windows, Linux or in the browser with Avocode.
Open your design and make sure that you have pt set as Measure tool units (default for iOS projects). You can change the units in Design settings/Interface.
Choose the Measure tool (press R key) and click on layers to find out their precise size. If you hover your mouse to other layers, you'll get lines telling you precise distances.
You can also select multiple layers by dragging your mouse over them and then again find the size and distances to other layers. All measurements will show up on the design canvas as weel as in the Styles and Code panel in the sidebar.