A gutter size calculator

[#1]

"What's the best margins/gutter size to use for my book?"  This is a common question I often see.  While margins are more of an author's general preference, the gutter case could use a calculator.  The gutter calculator only works for perfect bound books of any type or size.  Here's the formulas, in C-programming style (there are two separate formulas, one for black and white (since it uses thinner paper) and another for color (since it uses thicker paper)):

BWGutter = TotalPages/1776.0 + StressLimit - (SmallestSideMargin-0.5);

ColorGutter = TotalPages/1600.0 + StressLimit - (SmallestSideMargin-0.5);

TotalPages - the number of pages the book has.  This should be rounded up to the next multiple of 4 (meaning 273 becomes 276 and 412 stays as 412) due to the addition of blank pages so it's a multiple of 4.  This rounding up can be omitted since it has very little effect.  444 B&W leaves and 400 color leaves make an inch but there's two pages to each leaf and two leaves simultaneously visible which is where the 1776 and 1600 come from.  A thinner book means fewer pages obstructing the central part (compare a big 1500-page dictionary to a 150-page book once).

StressLimit - the amount of stress the author wants on the book's spine and binding.  This is more of an arbitrary value.  The higher this, the less the pages need to be spread and forced apart in order to read the text on the inside.  I've proposed 5 choices with preset values.  Maximum uses 0, high uses 0.05, medium uses 0.125, low (recommended balance) uses 0.2, and minimal uses 0.3.  A lower value allows slightly more text on a page which can slightly reduce cost, but it puts more stress on the spine and binding.

SmallestSideMargin is the smaller of the left and right margins (e.g. if left was 0.6 and right was 0.7, you'd use the 0.6).  The higher the margins are, the less of a gutter is needed since the margins sort of play like the gutter.

If the end result is negative (from the margins part), the result displayed should be 0.  Otherwise, the result displayed is whatever turns up.

This calculator should only function as a guide line but it should be quite useful for the beginners, even experts.

As an example, let's say I have a book that's black and white, 420 pages, with margins being 0.6 all around and low stress.  The formula should return a value of 0.3365 (2 or 3 decimal places are fine).

[#2]

I can't understand that, but it sounds like a great idea to me.