Bootstrap 03 : Standard grid with Even gutter widths
A non fix

This is the basic grid structure built using the Dreamweaver. It is identical to BS01 but has a gutter width set to 16px.

see: The Subtle Magic Behind Why the Bootstrap 3 Grid Works

Original gutter widths

The default bootstrap creates gutters between the columns that appear twice as wide as the margins on the outer side, this is because the margin is set either side of a column, which sits within a row that has a negitive margin of the same size. In this case the row has a margin of -15px and the columns a margin of 8px. Ad that row sit's in a container with a margin of 15px

So. the default is, in this order, container: padding 15px. row: margin -15px. column: padding 15px. Leaving a gutter of 30px between columns and a margin on 15px left and right of the container.

col-md-12
item
col-md-6
item
col-md-6
item
col-md-6
col-md-6
item
col-md-6
item
col-md-6
col-md-6
item
col-md-6
item
col-md-4
item
col-md-4
item
col-md-4
item

However

Changing the container padding to 0 and the row margin to 15px only works until you have to nest rows.
which is a shame.

col-md-12
item
col-md-6
item
col-md-6
item
col-md-6
col-md-6
item
col-md-6
item
col-md-6
col-md-6
item
col-md-6
item
col-md-4
item
col-md-4
item
col-md-4
item
col-md-3
item
col-md-3
item
col-md-3
item
col-md-3
item