Take a look guys:
"When CD Projekt claimed that The Witcher 3 will be absolutely massive in scale, they weren’t joking. Thanks to a few NeoGaf users we can finally compare the map size of The Witcher 3 to several other open world games. So far the Witcher 3 map is around 136 km2 which only includes Novegrad, No Man’s Land and Skellige Islands. There are are around 4-6 regions more who sizes are unknown at this point.
That means The Witcher 3 is at least 3.7 times bigger than GTA: San Andreas (36 km2), 1.5 times bigger than GTA 5 (81 km2), 3.3 times bigger than Red Dead Redemption (41), 3 times bigger than Far Cry 4 (46 km2) and 3.5 times bigger than Skyrim (39 km2). In short, the final map will be absolutely massive in scale.
Read more at
http://gamingbolt.com/witcher-3-map-size-compared-to-gta5-skyrim-far-cry-4-new-screens-show-different-visual-settings#GWHtZdIhYADGh02M.99
Their sources is Neogaf. What do you think?