IP66 vs IP21
Head-to-head comparison of two IEC 60529 ingress protection ratings.
IP66 and IP21 are both IEC 60529 ingress protection codes, but they differ in solid-object protection (level 6 vs 2) and liquid protection (level 6 vs 1). IP66 is rated for dust-tight and powerful water jets (12.5 mm nozzle), while IP21 provides > 12.5 mm — finger and vertically dripping water.
IP66 is dust-tight and resists powerful water jets (12.5 mm nozzle, 100 kPa). A robust outdoor rating for equipment exposed to heavy rain, storms, or directed high-pressure hosing (but not high-pressure washdown).
Designed for environments requiring protection against solid objects larger than 12.5 mm and protection against vertically falling drops of water. Dripping water shall have no harmful effects., IP21 is an IEC 60529 code combining solid level 2 with liquid level 1.
Detailed comparison
The stronger rating on each row is highlighted in emerald.
Solid protection (first digit)
IP66
6 — Dust-Tight
IP21
2 — > 12.5 mm — Finger
Liquid protection (second digit)
IP66
6 — Powerful Water Jets (12.5 mm nozzle)
IP21
1 — Vertically Dripping Water
Dust-tight
IP66
Yes
IP21
No
Water-jet resistant
IP66
Yes
IP21
No
Submersible
IP66
No
IP21
No
Outdoor suitable
IP66
Yes
IP21
No
The exact difference (IP66 vs IP21)
Solid protection
IP66
Level 6 — Dust-Tight
IP21
Level 2 — > 12.5 mm — Finger
IP66 provides "Dust-Tight" (level 6), while IP21 provides "> 12.5 mm — Finger" (level 2). IP66 is 4 levels higher.
Liquid protection
IP66
Level 6 — Powerful Water Jets (12.5 mm nozzle)
IP21
Level 1 — Vertically Dripping Water
IP66 handles 100 kPa (Powerful Water Jets (12.5 mm nozzle)), while IP21 handles 0.1 mm/min drip rate (Vertically Dripping Water). IP66 provides 5 levels more liquid protection.
NEMA equivalents
Recommendation
IP66 offers higher overall protection than IP21. Choose IP66 for harsher environments; IP21 may suffice for milder conditions and can be more cost-effective.