Print a grid at its exact scale so that, for example, each square is exactly 1/4" and not slightly off?

Precise grids can be really important for some projects, yet printing graph paper with grids that are precise is challenging for many home and office printers. The process of sending a file to a printer and how it processes it for printing can introduce slight distortions that affect grid accuracy.

IF your printer is not printing precisely accurate grids, correcting the distortion may require a bit of perseverance because printed results vary with combination of the printer and software (printer drivers) being used. While some printers can print to the edge of a page, most do not. Some printer drivers (software) compensate for the un-printable page margins and adjust (scale) what is being printed so that everything fits on the page. Unfortunately, it can take a bit of trial and error to correct the problems introduced by the printers and drivers that use scaling. For many tasks, a slight shrink in what is being printed does not matter. However, if you need precise sizing (for example, to print graph paper), it matters a lot! There is no single, quick fix — however — the suggestions below should help you find a way to control printer scaling.

PRINT PDF FROM A MAC OR PC COMPUTER
It's not surprising you may have trouble printing at the correct size directly from your phone or tablet. Printing from an iPhone or iPad is often “simplified” so that you don't have all the options and controls available that one has when printing from a Mac or PC computer.

Therefore, the first thing to try is to email (or AirDrop) the PDF to your computer.

From the More menu '•••', choose PDF. On the PDF page choose More, then Share.

Then, once the graph paper is uploaded, print the file from your computer after adjusting the settings to turn off scaling. For example, on a Mac confirm that “Scale to Fit” is NOT checked, and the scale is set to 100%.

Another advantage of sending the PDF to a computer for printing is that one can use the computer’s print scaling to print at a different scale. For example, if you wanted to print half size, use the print controls on the computer to print at a 50% scale.

PRINT PDF DIRECTLY FROM AN IPHONE OR IPAD
There are three modes for printing accessible from the PDF More menu '•••'. Two under Print and the other under Share.

Through trial and careful grid measurement, you'll likely find one of these will work with your printer and print drivers such that you will be able to print graph papers at an exact scale.

Print PDF option --
The “Print” option has two modes, General and Photo. Both options, General and Photo, communicate with your printer to try and find the proper size of paper. If you are using a “non-standard” size paper, one of these options may work successfully.

General
The printer/driver may try to “shrink” printing to fit within paper printing margins.
Photo
The printer/driver may try to “expand” printing for edge-to-edge paper printing.

Share PDF option --
The “Share” option assumes you are trying to use a “standard” size paper in your printer. Because printing a Custom size paper has its own challenges, the Share-to-Print mode may not be a viable choice to print a graph paper at the exact scale.

ALTERNATIVE APPROACH TO PRINT AT THE EXACT SCALE
If you can't get exact scale printing of a PDF using one of the app options above, there is one more approach to try. Following the iterative steps below will hopefully get you the proper result.

This example, from a iPhone (or iPad), show the steps necessary to correct for print scaling problems. Two approaches are explained in detail. One example uses an AirPrint capable printer and other uses the Brother iPrint&Scan app.

To make testing easier, I created a PDF with a grid that filled the page — edge-to-edge — for a 1/2” Grid, 5 Divisions per Grid. I'd expect these settings to print a grid with lines every 0.1”.

First, set paper size and margin settings:

Set page to US Letter size paper (8.5” x 11”)
Adjust margins to 0” on all sides

Set margins to zero

Open More menu for PDF

To print, choose PDF in the More menu. Then, on the PDF page, open More and tap Share. In the image below, behind the pop-up, you can see the PDF that is ready to be printed --

Share brings up two print options:

Print — near the bottom of the screen for AirPrint
Brother iPrint&Scan app — in the row of icons, scroll to find

Print: Select Print for the AirPrint option. It will show the preview screen below. Notice the grid runs to the edge of the page.

When the page is printed, the grid is printed at 1x (100%) scale (Which is good!). However, because the printer cannot actually print to the edge of the page, the image is chopped off around the edges.

Of course, having the image 'chopped off around the edges' may or may not be what you want. For a better finished page, leave the app set to the default print settings margins and the grid will be placed within the margins. If you want to control placement of the grid, read another How do I? write up, "How to Adjust grid placement on page".

Brother iPrint&Scan: Select the Brother iPrint&Scan app to get the preview screen shown below. Again, the grid runs to the edge of the page.

From the preview I can see that the image is shrunk to fit within a margin framing the edges. Unfortunately, the image has been scaled so that it fits inside the printer’s margins when printed. While this type of scaling is typically not a problem for text or many other documents, however, it is adds exactly the distortion we are trying to get around.

Follow these steps to find the proper adjustments to make:

Print the page
Carefully measure the printed area. In this case, the printed area was about 8.14” across by 10.56” down.
Use these dimensions to re-set the page size. (We are assuming the printer driver will act in the same way, adjusting the margins for printing so that the page size will be what we expect.)

Open Page Settings.
Scroll page size to "Custom".
Using the Custom setting, specify the page width and length (in this example 8.14" x 10.56")
Set the margins to 0” (to prevent doubling-up margins.)

By using the custom page size to control the printed area, the overall effective scaling should come out at 1x (100%). Print and measure again. If it is just 'pretty close', repeat the process of fine-tuning/printing/measuring until it is just right. (It's tough to measure accurately to 1/100”!)

A CLOSING THOUGHT
Compensating for printer driver scaling takes persistence. Congratulations for sticking with it!

If you find that your best option for controlling printing is to use Custom page size, you may find it helpful to write down the custom page size that works so you don’t have to go through the process of calculating it again for other papers... or create a "master" grid with these settings and duplicate it as the starting point for new papers. (TIP: A long press on a paper on the list page will quickly bring up file options including Duplicate.)