Using the Measure tool (Photoshop)

The Measure tool calculates the distance between any two points in the work area. When you measure from one point to another, a nonprinting line is drawn and the options bar and Info palette show the following information:
• The starting location (X and Y)
• The horizontal (W) and vertical (H) distances traveled from the x- and y-axes
• The angle measured relative to the axis (A)
• The total distance traveled (D1)
• The two distances traveled (D1 and D2), when you use a protractor
All measurements except the angle are calculated in the unit of measure currently set in the Units & Rulers preference dialog box. For information on setting the unit of measure

To display an existing measuring line:

Select the Measure tool .

To measure between two points:

1. Select the Measure tool .
2. Drag from the starting point to the ending point. Hold down the Shift key to constrain the tool to multiples of 45°.
3. To create a protractor from an existing measuring line, Alt-drag (Windows) or Option-drag (Mac OS) at an angle from one end of the measuring line, or double-click the line and drag. Hold down the Shift key to constrain the tool to multiples of 45°.

To edit a measuring line or protractor:

1. Select the Measure tool .
2. Do one of the following:
• To resize the line, drag one end of an existing measuring line.
• To move the line, place the pointer on the line away from either endpoint, and drag the line.
• To remove the line, place the pointer on the line away from either endpoint, and drag the line out of the image.
Note: You can drag out a measure line on an image feature that should be horizontal or vertical, and then choose Image > Rotate Canvas > Arbitrary. The correct angle of rotation required to straighten the image will already be entered into the Rotate Canvas dialog box.