How To Use A Chalk Line

Tips for making accurate, straight lines using a chalk line.

Hand holding a chalkline with a thumb on the string | Construction Pro Tips

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There's something almost magical in the way a simple chalk box creates a crisp, perfectly straight line in the blink of an eye. No other tool, except an expensive laser, makes a perfectly straight line over a long distance so quickly and reliably. In this article, we'll show you how to use a chalk line and provide tips that will make it easier to get good results.

Loading blue chalk into a chalkline | Construction Pro Tips

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Load the chalk

Fill the chalk box about half full with powdered chalk from a squeeze bottle. Tap the chalk box occasionally to settle the chalk. You’ll have a choice of red, blue, white or fluorescent chalk. Fill your chalk box with blue chalk for general use.

Hooking a chalk line on a nail to make a line | Construction Pro Tips

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Snap a basic line

Hook the end and stretch the string tight so it crosses directly over your mark. Reach out as far as you can and grab the string between your forefinger and thumb. To chalk a line, lift the string straight up about 4 in. and release it (it’ll snap to the floor).

Stretching past a mark to make a line with a chalkline | Construction Pro Tips

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Snap angle lines on wood

Mark angles on plywood by tacking a small nail to your mark, hooking the end of the string on it and stretching the string to the other mark.

Making a line on a piece of drywall with a chalk line | Construction Pro Tips

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Mark angle lines on drywall

Cut a slit in drywall with a utility knife and slip the string into it to secure the end. Cut the slit a little above the mark so the line will hit the mark when it’s extended for an angle cut.

Snapping a chalk line on shingles | Construction Pro Tips

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Snap lines on shingles

Chalk a line on shingles by hooking the end of your string into a slit cut in the shingle with a utility knife or hook blade.

Snapping an extra long line with a chalkline | Construction Pro Tips

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How to snap long lines accurately

Stretch the string taut. Use a helper or another nail to hold the chalk-box end of the string. Press down on the string about midway between the ends with your thumb or finger and hold it. Lift and snap the string on one side and then the other using the technique shown. This technique is good for irregular surfaces and will help prevent unwanted double lines.