What is a proportion grid?

A proportion grid divides both your reference image and drawing surface into equal squares. You then draw the contents of each small square one at a time, making it much easier to maintain accurate proportions when scaling up or down.

How many grid squares should I use?

For most drawings, 4-6 columns works well. More squares (8-12) give you more accuracy for detailed subjects like portraits. Fewer squares (3-4) are fine for simpler subjects or quick compositions.

Can I use a grid for any size change?

Yes. A proportion grid works for scaling up (enlarging) or scaling down (reducing). The grid preserves the relative proportions regardless of size change. The key is that both grids have the same number of rows and columns.

How do I draw the grid lines?

Use a hard pencil (2H or 4H) and a ruler to draw light lines on your drawing surface. Draw them lightly so they can be erased later. On your reference, you can draw directly on a photocopy or use a clear acetate sheet overlay.

ArtCalcs

Proportion Grid Calculator — Scale Reference Images

Calculate grid dimensions for scaling a reference image onto your drawing surface.

Reference Width

Width of your reference image

Reference Height

Height of your reference image

Drawing Width

Desired width of your drawing

Columns Across

Number of grid squares across

How We Calculate This

This calculator works out grid dimensions for both your reference and drawing surface using the formula:

Drawing height = Reference height x (Drawing width / Reference width)

The grid columns are set by your chosen number of squares across. The rows are calculated proportionally from the aspect ratio. Each square on the reference maps exactly to a corresponding square on the drawing.

Frequently Asked Questions

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Last updated: February 2026

All calculations are estimates. Always verify quantities before purchasing materials.