Grid Systems : Calculate grids for layouts in InDesign with the help of the Easy Grid Calculator

One of the tools I have used while calculating a grid for a layout was an Excel file I had used to experiment with different kinds of calculation methods. A collection of over a dozen different calculators for finding out different elements of the grid. I finally glued the different parts together and placed online as the Easy Grid Calculator – Square Units, or if you prefer, Easy Grid Calculator – Proportional Units, free for everyone to use (donations welcomed of course). The Easy Grid Calculator will save you a lot of time-consuming calculations and allow more time experimenting. Now it is time to dive into what this calculator is all about.

Usually, I prefer to base my layout grids on equal sided squares, each square being a grid unit to calculate the layout. The height of the squares is the same as the leading of the main text in the document. The width is as close to the height as possible. It’s rare to get 100% square, but the calculator gets you very close. More about that later on.

Let me guide you through the elements of the calculator one by one to explain what they do.

Page Size

Start by setting the size of your page, poster, business card or whatever you are designing in millimeters into the Paper Height and Paper Width.

Then you put in the leading you want to use the Original Leading field. In the example here the page height is 297 mm. Dividing into this with 12 pt leading you would get 70.15 lines for the grid lines. What the calculator does is to round this number to 70 and then use it to divide into the page height again. The result gives us 12.027 pt as a new leading. This Correct Leading (see next section) is very important. It is the key to the whole calculation. It is used to calculate the grid and also to set the Document Grid and Baseline Grid in InDesign.

Grid Settings

In this section, we get all the starter results which we calculated from the page size and leading.

First we have the Correct Leading as explained above. The Horizontal Leading 11.905 pt is the result of the same kind of calculation as the Correct Leading but for the width. The result gives us the width of the Grid Units and a number we can use to fill in the Horizontal > Gridline Every in InDesign.

As you see in this example, the height and the width of the Grid Unit is not a perfect square. But it’s very close, in this case, 0.12th of a point. You will have to zoom very deep to see a difference. Ratio H:W is simply to see how far we are from a one by one proportion.

Baselines is the number of lines from top to bottom of the page when Correct Leading is used. Baseline and Horizontal Lines are mainly useful to those who are making grids in Illustrator. In InDesign, you don’t need to know.

Imagelines are always one less than the Baselines and are an aid to adjusting the height of pictures to the type. The start of the first Imageline is calculated in the Imageline-section.

Margins, Columns and Rows

You have to play with the Margins, Columns and Rows all at the same time. It’s a good idea to start experiment with your layout by deciding on the Margins. You will undebatably have to change it few times before you complete your calculations.

Start by putting in numbers in the Left and Right input fields of the Margins. These are Grid Units and you can see in millimeters how wide your margins will be. Put 2 in Left and Bottom fields. These play with the Columns section. Let’s say you want to divide your layout into three columns. You see immediately that Line in Columns gives us 14.666 lines. This does not add up and we need to make some adjustments. In the Total Column Units we have 44 grid units at the moment. Closest match is 45 grid units. This means we can need one unit from the Margins to make it fit. But that would make the Margins too narrow. So instead we’ll go the other direction and add more units to the margins. Set Left to 3 units and you will see from the Closest match that now we only need only to add one more unit to the Margins. Set Right to 3 and everything fits.

Gutter units are for the gutter as the name implies. This field is good to have if we want wider gutters and when we are using very small leading. Then we might want to have more than one units for the gutter

We use the same method for the Rows as for the columns. Try 3 units for both Top and Bottom fields. Let’s say you want to divide your layout into 6 rows. You see immediately that Line in rows gives us 9.83 lines. In the Total Row Units we have 59 grid units at the moment. Nearest match is 60 grid units. We only need to move one unit from the Margins to make things fit. Let’s change Bottom to 2 units and we are ready to go. Try various unit numbers to get a better feeling of how this works.

In the case when you want to use greater leading, smaller page size or even more columns and rows you will find it harder to make things fit. There are a number things you can do to make it easier.

Consider to use smaller grid units that at the same time can be divided into the original leading you had in mind. For 12 pt you could use 6 pt leading in the Original Leading or even 3 or 4 pt. The Easy Grid Calculator takes care of the math, and when you start to put your numbers into InDesign, you can multiply inside the fields. As you probably already know all input fields inside InDesign and Illustrator are little calculators. You can for instance type for 6 pt leading: 6.013*2 and get 12.027 pt and so on. Using smaller grid units gives you much more flexibility.

You can also try to adjust the Original leading. Let us say that 15 pt leading is giving you problems calculating. Try to use 14.75 or 15.25. It’s all a matter of experimenting.

Size of textbox

This is the result of the page size minus the margins. Aligning the top of images to the imagelines. You may never have to use this information, but this can be handy to have in special cases, like when you want to make use of scripts like the included Make Grid.jsx or Add Guides.jsx.

Imagelines

Imagelines are an optional guidelines you can add to your layout to align the top of images to. They are based on the height of the f or the l (lower case L). Some even prefer to use the x height of the font.

To find out the height of the f, type it into InDesign in the font size you are going to use. Select the f and go to Type > Create Outline. Select the outlined f and the height should be displayed in the Control Panel. For example 9 pt Helvetica Neue turns out to be 2.292 mm and this number is put into the field. The output number tells where the first line should be put. Then it’s just the matter of using Edit > Step and Repeat to add the rest of the guides. Take the Imageline number from the Grid Settings section (69) and use the Original Leading (12.027 pt) for offset. It’s a good idea to have the imagelines on a separate layer to avoid clutter.

This is all you need to calculate your layout grid for either InDesign or Illustrator. I hope I managed to explain the use of the Easy Grid Calculator and that this will save you some time.