Ruler/Measure Tool

[Graham.M 1]

Maybe I've just not found it yet. Is there a tool that will allow me to measure the distance between two points in my image?

[Dave Quail 56]

I use

1/. the Rectangle Tool (U) to drag out a measurement, shown just above the cursor before you lift your finger off the mouse button.

2/. The Node Tool (P), which also displays the the measurement before you lift off the mouse button.

At this stage there is no direct equivalent to the Ruler Tool (I) on the Eyedropper Tool (I) in PS.

[dmstraker 378]

If you're using regular sizes, you can set a grid and snapping (so no need to measure). Otherwise a non-snapped grid will still let you get a quick approximate measurement.

You can also set guides and snap to these. Guides also show absolute position (needs a bit of subtraction).

When I'm doing frequent same sizes, I'll sometimes set up a bunch of rectangles for each size and then snap to these. Or sometimes a 'square wave' with the pen tool (good for rescaling).

Rectangles are also a good way to transfer a measure from one place to another. You can even rotate a rectangle (and hold down shift for snapped 15' increments).

If you go to the Transform tab it will show you the position/size of selected rectangle (including after you have released it). You can set/change the rectangle size from here too.