It depends on the used type size. It should be good visible for common eyes. So its big on 9pt and very big if you set smaller text. On larger text sizes it becomes smaller. So you should choose a size for what your design best fits for - mostly body text or display.

I think the R in the registered sign should have the same size (caps high) as the TM mark - but maybe it depends on personal taste. I see very often a different approach.

Lots of fonts don't care much about such issues and use a standard sign and size.

my suggestions to start from:
(percentage of the caps high)

4-8pt: bigger
9-12pt: 55 - 47%
16-28pt: 45 - 40%

--astype.de--

I also think you need to consult with your legal department. TM, ®, SM are all legal designations and there are rules for their use.

I'm working on a logo design right now, where I'm supposed to add an registered (R). Does anyone no about any legal or typographic rules how to place the (R)? Can I place it anywhere close to the logo or does it have to be at the lower or upper right corner? Any certain rules about the size? Or is there a minimum percentage for the size in relation to the logo?

They just needs to be legible. I usually make them as small as I can, while still being legible.

In fact legally they aren't even mandatory at all, but they provide additional legal protection in case of a lawsuit. Here's a quote from the International Trademark Association:

"Use of the registration symbol or other statutory notice is not mandatory, but it is important not only because it provides notice of the owner's registration of the mark, but also because it allows the owner to assert certain types of damages in lawsuits against infringers. Failure to use a registration notice limits the remedies available to a trademark owner in a lawsuit..."

So in other words, the government doesn't require them, but if company X sues company Y for infringement, the lawyer for company X can say, "They should have known it was a registered trademark because we put the symbol on it."

But it does actually have to be registered to warrant the ® symbol. If you use the symbol on a trademark that has not been accepted for registration, that could be construed as fraudulent.

> But it does actually have to be registered
> to warrant the ® symbol

Yes, the International Trademark Association says:

"A ™ is usually used to indicate an unregistered trademark. It is an informal notification that there is a public claim as a trademark...

"The ® (commonly pronounced "R-in-a-circle" or "Circle-R") is a warning notice to advise the public that the mark is registered and their use provides legal benefits. This notice can be used only with registered marks. Use of a ® with any unregistered trademark may result in claims of fraud..."

This is one factor that may influence the designer to make different optical sizes for a logo. See this thread

In fonts, the informal standard is that "Registered" and "Copyright" are cap-height.
"Trademark" is generally rendered as a superscript, about the same relative size as other superiors such as figures and ordinals.

"Registered" and "Copyright" are cap height, even thought they will be reduced in the main text, because they are also required in reference footnotes, so it is up to the typographer to superscript and downsize them for use in running text and logos: there are defaults for this in Quark and InDesign, around 60 -70 %, IIRC, which is therefore the de facto standard.

"Trademark" is not cap height, because if it were, there is the likelihood it would be read as part of the preceding word, and be too wide in footnotes. So it can look too small in some footnotes. However, it doesn't require special superscript treatment by the typographer.

For logos, it's up to the discretion of the graphic designer/art director, but it's quite alright to make them very small, with the proviso, as Ben says, that if it is part of a logo that is going to be scaled, then the graphics standards for a corporation should provide different versions of the logo for use at different sizes.

AFAIK, infringement has never been legally defended on the grounds that the infringer didn't see the mark because it was too small in a document, but I'm not a trademark lawyer, so perhaps it has happened!

In a few typefaces (such as those of my Modern Suite), there are alternate, optically scaled glyphs for "Registered" and "Copyright", accessible through the OpenType "Superscript" feature.

thanks everyone for the helpful answers! and - yes - it is a registered trademark, so I'm on the save side using the (R).

Correction: it's only the "Registered" that is provided as a superscript in the Modern Suite (along with Dagger and Double Dagger).