I have a layer of color Red. It is a little transparent. I want to find actual RGBA value of it. The opacity is in percentage an I want the hex value of it. Is there any way, thanks.
If you have a background layer or any layers underneath the colour you wish to sample, hide them in the layers panel by unchecking the Eye icon, so that you can see the transparency grid through the colour. You can unhide them later.
Do Windows > Dockable dialogs > Sample points
Hold down Ctrl and click and drag from the ruler to drop a sample point on the colour you wish to sample.
The RGBA values will be displayed in the Sample Points Panel.
Convert the decimal numbers to hexadecimal using an online converter. For example the above sampled values would be #ff00006d