Is this coffee mug printable?

That is a really small mug. Did you make sure to assign the correct Unit scale? On default I think the up-loader is set to Millimeters. Edit your model and on the second page check your Unit scale and make sure it is set to centimeters.

Piece of advice: if you plan to post the Mug on other 3d print sizes outside of cgtrader, convert your unit scale to millimeters. Most people who purchase models to print on their home printers have their slicing software set to use millimeters.

Thanks for help! I changed the unit to cm and now it shows 0.01 cm in every dimension. In blender I'm useing the metric system where the object has the correct size.

I think you have the display scale set to metric, but not the system scale to match and thus Blender is exporting at whatever it thinks 1 unit equals. I haven't used blender in a while so I don't remember how to set the system scale in blender.

You could always download netfabb and fix the scaling in the program. Netfabb is free.

I checked the file with netfabb. Everything fine there.

What are the dimension that nefabb gives you? If you say you model is 12 cm x 8 cm x 8 cm. That should translate to 120 mm x 80 mm x 80 mm. If it doesn't say that, then you should scale the model and export it out of netfabb.

The dimentions in netfabb are correct, 116.00mm X 83.90mm X 88.25mm. I also checked the file with cura and slic3r. Also there everything correct.

If you can find a contact link for support, notify Cgtrader of the website bug. Thats weird that the site is displaying incorrect dimensions.