Water Resistance: Decoding ATM & IP Ratings (2025 Guide)

Water Resistance: Decoding ATM & IP Ratings (2025 Guide)

If you plan to swim, surf, or even just wear your watch in the shower, you’ll need to understand water resistance ratings.
This guide explains ATM and IP ratings so you can pick the right smartwatch or training watch with confidence.

1. What does “ATM” mean?

ATM = atmospheres of pressure a watch can withstand.

  • 3 ATM (30m) → Splash-resistant. Fine for rain or washing hands, NOT swimming.
  • 5 ATM (50m) → Safe for swimming in shallow water. Many Fitbit and Garmin watches fall here.
  • 10 ATM (100m) → Suitable for swimming, snorkeling, and water sports. Most Garmin Fenix/Epix, Suunto, COROS.
  • 20 ATM (200m) → Professional diving level. Found in specialty models (Garmin Descent, dive watches).

⚠️ Important: “30m” or “50m” doesn’t mean you can dive that deep—it’s based on lab tests under static pressure. Real-world use (movement, waves, temperature changes) puts more stress on seals.

2. What does “IP” mean?

IP = Ingress Protection rating, used more often in smart devices.
It has two digits:

  • First digit = Dust protection (0–6).
  • Second digit = Water protection (0–9).

Examples:

  • IP67 → Dustproof + resistant to immersion up to 1m for 30 minutes.
  • IP68 → Dustproof + resistant to >1m immersion (varies by brand).
  • IPX7 → Water resistant only (no dust rating).

Some smartwatches (Apple, Samsung, Fitbit) use IP ratings in addition to ATM ratings.

3. Real-world scenarios

  • Daily wear (rain, hand washing) → 3 ATM or IP67 is fine.
  • Pool swimming → 5 ATM minimum.
  • Surfing, snorkeling → 10 ATM recommended.
  • Diving → Look for dive-specific watches (20 ATM + EN13319 certification).

4. Common manufacturer ratings

  • Apple Watch Series & Ultra → WR50 (50m), IP6X dust resistant. Ultra = WR100.
  • Garmin Forerunner → 5 ATM (50m).
  • Garmin Fenix/Epix/Instinct → 10 ATM.
  • Suunto Vertical → 10 ATM.
  • COROS Vertix 2 → 10 ATM.
  • Fitbit Sense/Versa → 5 ATM.
  • Samsung Galaxy Watch → 5 ATM + IP68.

5. Things to watch out for

  • Chlorine and salt water → Rinse your watch after swimming.
  • Hot water → Avoid wearing in hot tubs or saunas (seals degrade faster).
  • Button use underwater → Many watches warn not to press buttons while submerged.
  • Aging seals → Water resistance weakens over time; replace gaskets if needed.

Final takeaway

Water resistance is one of the most misunderstood specs.

  • ATM = lab-tested pressure resistance.
  • IP = dust + water resistance.

For most buyers:

  • Casual swimmers → 5 ATM is fine.
  • Serious water athletes → 10 ATM or higher.
  • Divers → specialized dive watches only.

Choose based on your real-world use—not just the number on the spec sheet.