Wire nut size and colour chart

Which Zone wire nut fits which wire: the wire range in AWG for every Zone cap, by colour, exactly as published on its listing.

Wire nut sizes by colour

Colour	Zone SKU	Type	Wire range	Listing	Packs
Orange	P3	Standard	22–14 AWG	UL 486C	500
Blue	P2	Compact, low profile	22–14 AWG	UL 486C	1000
Red	P6	Standard	22–10 AWG	UL 486C	500
—	R3	Waterproof, silicone-filled	20–10 AWG	UL 486G	100, 25
Yellow	P11V	Winged	18–10 AWG	UL 486C	500, 1000, 100
Green	P99	GroundingPigtail hole	14–10 AWG	UL 467	100
Tan	P12C	Winged	22–8 AWG	UL 486C	500
Red	P13	Winged	22–8 AWG	UL 486C	500, 1000
—	R6	Waterproof, silicone-filled	20–8 AWG	UL 486G	100, 20

Each pack size links to its Amazon listing. Wire range and listing as Zone publishes them there.

The same ranges, read the other way: a dot means the wire size is inside that cap’s published range.

Cap	22 AWG	20 AWG	18 AWG	16 AWG	14 AWG	12 AWG	10 AWG	8 AWG
P322–14 AWG	●	●	●	●	●
P222–14 AWG	●	●	●	●	●
P622–10 AWG	●	●	●	●	●	●	●
R320–10 AWG		●	●	●	●	●	●
P11V18–10 AWG			●	●	●	●	●
P9914–10 AWG					●	●	●
P12C22–8 AWG	●	●	●	●	●	●	●	●
P1322–8 AWG	●	●	●	●	●	●	●	●
R620–8 AWG		●	●	●	●	●	●	●

Find the sizes of the wires you are joining, in AWG. The size is printed on the wire jacket.
Pick a cap whose published range includes every one of them. The smallest and the largest wire in the splice must both be inside the range.
Read the range on the pack, not the colour alone. Colour marks the size range on Zone caps, but colours are not the same from one brand to another.
Wet, damp or buried? Use a silicone-filled cap listed to UL 486G: waterproof direct-bury wire nuts. Grounding? The green cap with a hole is listed to UL 467.