If we are going to go by Starsector ship sizes, i made one a while back that is included in my mod.

These sizes are what starsector can handle regularly without consuming all memory and causing an OutOfMemory Crash, also the true and most commonly used sizes for sprite classification.

Arkship ~ 1750 - 2500 pix

Titan ~ 750 - 1750 pix

Dreadnought ~ 650 - 750 pix

Mothership/Supercarrier ~ 550 - 650 pix

Battleship/Battlecruiser ~ 350 - 550 pix

Superheavy Cruiser/Heavy Cruiser ~ 300 - 350 pix

Superheavy Destroyer/Cruiser ~ 225 - 300 pix

Heavy Destroyer/Destroyer ~ 175 - 225 pix

Heavy Frigate/Heavy Gunship ~ 125 - 175 pix

Frigate/Gunship/Heavy Corvette ~ 75 - 125 pix

Corvette ~ 50 - 75 pix

Heavy Fighter/Bomber ~ 35 - 50 pix

Fighter/Interceptor ~ 20 - 35 pix

Heavy Drone/Drone ~ 5 - 20 pix

/ValkyriaL

To be honest, it should state if the pixels are the length and/or width of the respective ship.

To have a really accurate scale of what the ship could be classified as, the actual pixelmass (total number of pixels the sprite has) would be of more significance IMO.

FRIGATES

Hyperion Frigate frigates HIGH 2418

Hound Frigate frigates LOW 2843

Wolf Frigate frigates HIGH 3032

Omen Frigate frigates HIGH 3037

Tempest Frigate frigates HIGH 3380

Lasher Frigate frigates LOW 3884

Vigilance Frigate frigates MID 3954

Brawler Gunship frigates MID 4402

Shade Phase Frigate frigates HIGH 4790

Afflictor Phase Frigate frigates HIGH 5707

DESTROYER

Buffalo Mk.II Destroyer destroyer LOW 9304

Hammerhead Destroyer destroyer MID 11496

Enforcer Destroyer destroyer LOW 12279

Sunder Destroyer destroyer MID 12594

Medusa Destroyer destroyer HIGH 12622

Condor Light Carrier destroyer LOW 13062

Mule Combat Freighter destroyer LOW 13590

Gemini Freighter destroyer MID 14405

Valkyrie Troop Transport destroyer MID 16474

CRUISER

Falcon Light Cruiser cruiser MID 18124

Eagle Cruiser cruiser MID 22093

Venture Cruiser cruiser LOW 22304

Aurora Cruiser cruiser LOW 23845

Apogee Cruiser cruiser HIGH 24082

Dominator Heavy Cruiser cruiser LOW 27120

Doom Phase Cruiser cruiser HIGH 29652

CAPITOL

Odyssey Battlecruiser capitol HIGH 40722

Conquest Battlecruiser capitol MID 51804

Onslaught Battleship capitol LOW 64812

Paragon Battleship capitol HIGH 73625