nano-banana Reference Sizes

Corresponding resolutions and aspect ratios.

The size parameter can accept either dimension or ratio.

nano-banana and gemini-2.5-flash-image do not support 2k and 4k sizes.

nano-banana-pro and gemini-3-pro-image-preview support 2k and 4k sizes.

var sizeMap = map[string]struct{ k, aspectRatio string }{
	"1024x1024": {"", "1:1"},
	"2048x2048": {"2k", "1:1"},
	"4096x4096": {"4k", "1:1"},
	"832x1248":  {"", "2:3"},
	"848x1264":  {"", "2:3"},
	"1696x2528": {"2k", "2:3"},
	"3392x5056": {"4k", "2:3"},
	"1248x832":  {"", "3:2"},
	"1264x848":  {"", "3:2"},
	"2528x1696": {"2k", "3:2"},
	"5056x3392": {"4k", "3:2"},
	"864x1184":  {"", "3:4"},
	"896x1200":  {"", "3:4"},
	"1792x2400": {"2k", "3:4"},
	"3584x4800": {"4k", "3:4"},
	"1184x864":  {"", "4:3"},
	"1200x896":  {"", "4:3"},
	"2400x1792": {"2k", "4:3"},
	"4800x3584": {"4k", "4:3"},
	"896x1152":  {"", "4:5"},
	"928x1152":  {"", "4:5"},
	"1856x2304": {"2k", "4:5"},
	"3712x4608": {"4k", "4:5"},
	"1152x896":  {"", "5:4"},
	"1152x928":  {"", "5:4"},
	"2304x1856": {"2k", "5:4"},
	"4608x3712": {"4k", "5:4"},
	"768x1344":  {"", "9:16"},
	"768x1376":  {"", "9:16"},
	"1536x2752": {"2k", "9:16"},
	"3072x5504": {"4k", "9:16"},
	"1344x768":  {"", "16:9"},
	"1376x768":  {"", "16:9"},
	"2752x1536": {"2k", "16:9"},
	"5504x3072": {"4k", "16:9"},
	"1536x672":  {"", "21:9"},
	"1584x672":  {"", "21:9"},
	"3168x1344": {"2k", "21:9"},
	"6336x2688": {"4k", "21:9"},
}