find out the gradient start and end values of small distance out of larger distance

Question

I have the following design with gradient

:

The gradient is 348px long, linear, starts with #F7F7F7 and ends with white #FFFFFF. I need to know what gradient color should I put as a starting point if I want my gradient to be not 348px, but 270px (shown by red line) with keeping to the original design. Is that possible?

Answer 1

I understand your question differently than boblet. What I think you want is a the colour that is interpolated by the gradient at 78px from the bottom of the gradient. I don't know a method to exactly determine it, only how to approximate it.

First create your original 348px gradient. For the colours I used black and white for clarity.

Then place a guide at 78px from the beginning of the gradient. Now select the rectangle that has the gradient, go to Object -> Expand, you will see this window:
Make sure you expand the gradient to objects, not as a gradient mesh.

Now you can double click the rectangle (which now is a group) to enter Isolation mode and select one "piece" of the gradient closest to the previously set guide.

The fill colour of that piece is displayed in the colour panel, you can drag it as a swatch to save it.

Now use that colour as the starting point of your new, 270px gradient.

Answer 2

Not entirely sure what you want, as I do not really understand the reference to the height of the boxes. But I am going to give it a go:

You could move the largest box up:

You could alter the starting point of your gradient to be "longer" on the darker side:

Or you could skip the bottom box entirely:

You can add as many incremental colour point in the gradient slider as you like, by clicking a point on the slider:

Edit: oh, I forgot Object > expand > choose increments. That should give you something like this, and you can pick the level.