I'm curious if there are any known ergonomic effects of font weight choice. I already understand, for example, that the relative contrast of font color and background is important to reduce eye strain, and it seems intuitive that if the weight is decreased or increased too much that characters will become more difficult to read, but I'm curious if there are any known effects within more typical ranges - say the difference between "Calibri" and "Calibri Light."

It also seems intuitive that lighter font weights save on toner/ink in documents that are likely to be printed or reproduced frequently, but I have no data to support this conclusion either.

TL;DR: Does font weight matter for any non-aesthetic reasons?

2 Answers 2


Short answer: Yes.

With some printing methods, the actual accumulation of link on the page is a serious consideration -- it's why many fonts have/had small nicks ("ink traps") between the serif and the base, where excess ink could pool without distorting the letter shape.

In modern offset printing, the amount of ink spread/dot gain that occurs is important to consider for ultimate readability and appearance. With some paper stock, you might want to use a lighter font weight because it will gain some additional weight through ink spread. In other cases, you might use a heavier weight because a particular stock/ink/screening combination could result in letterforms breaking up.

Some things to watch out for: non-solid colors used for text in offset printing with lower-grade stock; text landing on multiple color plates (registration problems); and especially, small (< 10 pt or so) reversed text in very light weights (registration problems result in letters filling in).

There are probably entire chapters and even books on the subject, but I hope that gives you some aspects to look at.


I would say balance is the right word.

The costs are part of the effort you want to put in conveying your message.

I've put balance in bold to emphasise the importance of it for this statement. If this was printed on paper, it would technically cost me more to emphasise it but I do want to put that effort into it as it enriches the message.(gain)

If a text is too light(or small), it will get lost and/or not read at all which makes the complete effort(writing, design, printing and publishing) go to waste.

So balance the effort/gain (how important is your message) and make sure to keep Light for headers/titles.

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