How to use the reading ruler on Mac
The digital version of holding a ruler under the line you are on. Genuinely useful for dense documents, and free.
Wide lines of dense text are hard to track. Your eye reaches the end of a line, travels back across the page, and lands one line too high or too low. In a novel that is an annoyance. In a contract it is a mistake.
The reading ruler dims the page except for a clear horizontal band that follows your pointer. It is the digital version of holding a ruler under the line you are reading.
The reading ruler is free and always will be. There is nothing to sign up for and nothing is watermarked.
Turning it on
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Open the inspector
The panel down the right of the window. Under Reading there is a switch for the reading ruler.
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Switch it on
The page dims immediately and a clear band appears under your pointer.
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Move down the page
The band follows the pointer. The up and down arrow keys nudge it a line at a time, so you can read without touching the trackpad.
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Keep working
The ruler never gets in the way of clicking the page underneath. Select text, follow a link, or use a markup tool with it on.
Who it helps
It was built for anyone who finds tracking across wide lines difficult, and it does that job well. But it earns its place for a much wider group than that:
- Anyone reading a dense contract. Clause-by-clause reading is exactly the case where skipping a line matters.
- Anyone proofreading. Forcing your eye to one line at a time is the oldest proofreading technique there is.
- Anyone reading a wide two-column document. The band keeps you in the column you are actually in.
- Anyone reading late. Dimming most of a bright white page is easier on the eyes at the end of a long day.
The ruler keeps your eye on the line; Read Aloud reads the line to you and highlights each word as it goes. Together they are a genuinely different way of getting through a long document, and both are free.
Setting it as the default
If you want it on for everything you open, set it in Settings rather than turning it on per document. The switch in the inspector then becomes a per-document exception rather than something you have to remember.
Frequently asked questions
What is a reading ruler?
A clear horizontal band that follows your pointer while the rest of the page dims, so your eye cannot slide into the wrong line. It is the digital version of holding a ruler under the line you are reading.
How do I turn on the reading ruler in a PDF?
Open the inspector on the right of the window and use the Reading ruler switch. To have it on for everything, set it in Settings instead.
Can I still click the page with the ruler on?
Yes. It never blocks the page underneath — you can select text, follow links and use markup tools with it on.
Can I move the band with the keyboard?
The up and down arrows nudge it a line at a time, so you can read a long document without touching the trackpad.
Is the reading ruler free?
Yes, permanently, along with Reading View and Read Aloud. The reading features are the part everyone uses every day, so they are the part that is free.
Does it work on scanned documents?
Yes. The ruler dims the page and clears a band, which works whether the page holds text or a picture of text.