There used to be a free website that provided cabin information but they went to a fee basis. Yes, Carnival generally has larger standard cabins than the other lines. 185 square feet is the norm for their standard cabins. RCCL's older ships (Sovereign, Monarch, Majesty, Empress) have really small standard cabins (119 sq ft) but they got away from that type of thinking with the newer builds, although they still don't approach Carnival's standard size. However, RCCL has a larger range of cabin choices and many of their categories are bigger than 185 sq ft.
Interior state rooms on board the Freedom of the seas:
PR--149 sq.ft; L/M/N/O--152 sq.ft
Ocean view state rooms:
Family suteroom: FO 293 sq.ft; F--214 sq.ft; H/I: 161 sq.ft
Deluxe Ocean view staterooms with balcony:
E1/E2--177 sq.ft; D1/D2--189 sq.ft
Presidential family suite--1,215 sq.ft, balcony 810 sq.ft
Holland America "Rotterdam and Statendam Class ships":
Inside Staterooms = 182 sq ft
Outside Staterooms = 197 sq ft
Veranda Suites = 292 sq ft (incl veranda)
Deluxe Veranda Suites = 556 sq ft (incl veranda)
Penthouse Suites = 1159 sq ft (incl veranda)
Regent Seven Seas Voyager:
From Standard Suites
~386 sq. ft.
~Suite: 306 sq. ft.
~Balcony: 80 to 137 sq. ft.
To Master Suites
~1,335 sq. ft.
~2-Bedrooms
~Suite: 1,152 sq. ft.
~Balcony: 183 sq.ft.
The Regent Seven Seas Mariner has some different sizes:
From Category MS
~2,002 sq. ft.
~Suite: 1,204 sq. ft.
~Side Balcony: 71 sq. ft.
~Fwd. Balcony: 727 sq. ft.
~2 bedrooms
To Deluxe Suite
~301 sq. ft.
~Suite: 252 sq. ft.
~Balcony: 49 sq. ft.