You can divide an image in GIMP in a row-column way with guide rows and the guillotine (paper cutter) tool. From GIMP User Manual:

In addition to the image grid, GIMP also gives you a more flexible type of positioning aid: guides. These are horizontal or vertical lines you can temporarily display on an image while you are working on it.

 

To create a guide, simply click on one of the rulers in the image window and pull out a guide, while holding the mouse button pressed. The guide is then displayed as a blue, dashed line, which follows the pointer. As soon as you create a guide, the “Move” tool is activated and the mouse pointer changes to the Move icon.

 

The Guillotine command slices up the current image, based on the image's guides. It cuts the image along each guide, similar to slicing documents in an office with a guillotine (paper cutter) and creates new images out of the pieces. You can access this command from the image menubar through Image -> Transform -> Guillotine.

You can divide an image in GIMP in a row-column way with guide rows and the guillotine (paper cutter) tool. From GIMP User Manual:

In addition to the image grid, GIMP also gives you a more flexible type of positioning aid: guides. These are horizontal or vertical lines you can temporarily display on an image while you are working on it.

To create a guide, simply click on one of the rulers in the image window and pull out a guide, while holding the mouse button pressed. The guide is then displayed as a blue, dashed line, which follows the pointer. As soon as you create a guide, the “Move” tool is activated and the mouse pointer changes to the Move icon.

The Guillotine command slices up the current image, based on the image's guides. It cuts the image along each guide, similar to slicing documents in an office with a guillotine (paper cutter) and creates new images out of the pieces. You can access this command from the image menubar through Image -> Transform -> Guillotine.

I wonder how come nobody came to this yet but,

With Gimp 2 You can divide an image in a row-column way with guide-rows and 'guillotine' [massicot / massicotte]

Display the ruler around your image Drag a guide from the ruler to your image Select Image > Transform > Massicot

Enjoy.

You can divide an image in GIMP in a row-column way with guide rows and the guillotine (paper cutter) tool. From GIMP User Manual:

In addition to the image grid, GIMP also gives you a more flexible type of positioning aid: guides. These are horizontal or vertical lines you can temporarily display on an image while you are working on it.

To create a guide, simply click on one of the rulers in the image window and pull out a guide, while holding the mouse button pressed. The guide is then displayed as a blue, dashed line, which follows the pointer. As soon as you create a guide, the “Move” tool is activated and the mouse pointer changes to the Move icon.

The Guillotine command slices up the current image, based on the image's guides. It cuts the image along each guide, similar to slicing documents in an office with a guillotine (paper cutter) and creates new images out of the pieces. You can access this command from the image menubar through Image -> Transform -> Guillotine.