Garmin 40mm Vs 45mm | One Saves Charge, One Fits Small

This vs That / By

For Garmin sizes, choose Vivoactive 4S (40mm) for a lighter fit; pick Vivoactive 4 (45mm) for a bigger screen and longer battery.

Choosing a Garmin size affects comfort, battery rhythm, and how easily you read stats on the move. Both models here share the same platform; the bigger case simply leaves more room for screen and cell. You’ll get a fast verdict and the trade‑offs that nudge a buyer one way or the other.

In A Nutshell

The smaller case suits slimmer wrists and anyone who wants a watch that disappears under a cuff. The larger case suits runners and gym‑goers who want larger text and a little more time away from a charger. The feature set is the same: GPS with multi‑sat options, music on‑device, Garmin Pay, safety tools, and Connect IQ apps.

Side‑By‑Side Specs

Feature Vivoactive 4S (40mm) Vivoactive 4 (45mm)
Cost $349.99 MSRP at launch $349.99 MSRP at launch
Case Diameter 40 mm 45 mm
Display & Resolution 1.1″ MIP, 218×218 1.3″ MIP, 260×260
Glass Corning Gorilla Glass 3 Corning Gorilla Glass 3
Battery (Smartwatch / GPS / GPS+Music) Up to 7 days / 15 hr / 5 hr Up to 8 days / 18 hr / 6 hr
Band System Quick‑release 18 mm Quick‑release 22 mm
Water Rating Swim, 5 ATM Swim, 5 ATM
GNSS GPS, GLONASS, Galileo GPS, GLONASS, Galileo
Wireless Bluetooth, ANT+, Wi‑Fi Bluetooth, ANT+, Wi‑Fi
Payments Garmin Pay Garmin Pay
Music On‑device storage; streaming via apps On‑device storage; streaming via apps

Vivoactive 4S (40mm) — What We Like / What We Don’t Like

✅ What We Like

  • Smaller case sits lower on the wrist, so it vanishes under sleeves and gloves.
  • 18 mm quick‑release bands give slim wrists a better fit without extra bulk.
  • Same platform as the larger model: GPS with multi‑sat options, Garmin Pay, music, safety alerts, and app downloads.

⚠️ What We Don’t Like

  • One fewer day in watch mode versus the larger case.
  • Smaller screen; tiny text can mean extra taps during runs or rides.
  • Shorter GPS+music time on long workouts.

Vivoactive 4 (45mm) — What We Like / What We Don’t Like

✅ What We Like

  • Extra screen real estate (260×260) makes pace, heart rate, and maps easier to read.
  • Longer runtime: another day in watch mode and more time for GPS + music.
  • 22 mm band size; strap choices are everywhere, from nylon to leather to sport silicone.

⚠️ What We Don’t Like

  • Bulk is easier to notice during sleep or tight‑cuff layers.
  • Heavier feel than the 40 mm model.
  • Small wrists may need the tightest holes on many 22 mm straps.

Garmin 40mm Or 45mm: Which Fits You Better

Both sizes run the same software, track the same sports, and log the same health metrics. The choice is about day‑to‑day comfort, legibility, and battery rhythm. Here’s how the size changes the experience in the areas buyers ask about most.

Performance & Speed

Menus and widgets move the same on both sizes. The watch OS is identical, and both carry the dual‑button layout that makes mid‑workout actions simple. If you’re coming from a one‑button Garmin, the extra button helps with laps and starting a new activity without digging through screens.

Display & Build

The smaller model uses a 1.1‑inch round Memory‑In‑Pixel panel at 218×218. The larger model steps up to 1.3‑inch at 260×260. That extra pixel count isn’t about graphics tricks; it’s about reading numbers faster while you’re moving. The glass is Corning Gorilla Glass 3 on both. (Screen resolutions are listed on Garmin’s Connect IQ compatible devices page.) See display specs.

Battery & Charging

Size helps battery. In watch mode with activity tracking and wrist HR, the 40 mm case is rated up to 7 days while the 45 mm is up to 8 days. GPS time tilts the same way: up to 15 vs. 18 hours with music off, and up to 5 vs. 6 hours with music on. These figures come from the owner’s manual battery table. See the Battery Life table.

Cameras & Sensors

There’s no camera on either watch. The sensors match: wrist HR with Pulse Ox, accelerometer and gyroscope, compass, and barometric altimeter. For positioning, you can pick GPS alone or pair GPS with GLONASS or Galileo for tougher skies. Garmin documents the satellite options and notes that multi‑sat tracking uses more power.

Software & Updates

Both sizes support Garmin Pay, on‑device music with streaming app downloads, safety features like LiveTrack and incident detection, and Connect IQ apps, data fields, and watch faces. The music player works with Bluetooth headphones and stores tracks for phone‑free runs; file support and storage guidance are in Garmin’s help pages.

Ports & Connectivity

Wireless is the same on both: Bluetooth for your phone, ANT+ for sensors, and Wi‑Fi for music and updates. That means you can pair foot pods, chest straps, bike sensors, and gym treadmills. If you’re coming from a tracker that only syncs by phone, Wi‑Fi feels faster for playlists and big app updates.

Pricing & Packages

Both sizes launched in the U.S. at $349.99. Street prices change with promos and colorways, so treat the official store as the reference point and shop around if you’re open to last‑season colors. The band situation matters more than you think: the 40 mm uses 18 mm straps and the 45 mm uses 22 mm, so check your spare bands drawer before you buy new.

ℹ️ Good To Know: The small watch takes 18 mm quick‑release bands while the large watch takes 22 mm. If you love a strap you already own, match the size so it fits your new watch.

Garmin lists both strap widths in the band‑change instructions. The water rating is Swim/5 ATM for both sizes. The battery table and water rating reference live inside the official manual (linked above), while screen resolutions appear on Garmin’s developer page (linked above).

Ownership & Value Snapshot

Here’s the bottom‑line math buyers care about after the sticker price. The picks stay feature‑equal; the shifts come from fit, readability, and how often you reach for the charger.

Factor Vivoactive 4S (40mm) Vivoactive 4 (45mm)
Daily Charging Rhythm About weekly for mixed use A bit longer between charges
Long Workout Margin (GPS + Music) Around a 5‑hour window Around a 6‑hour window
Strap Ecosystem 18 mm quick‑release 22 mm quick‑release
Readability At A Glance Good for small wrists Best for fast checks mid‑run
Sleep Wear Comfort Easier to forget on the wrist Noticeable for some side‑sleepers

Where Each One Wins

Where Each One Wins:
🏆 Comfort — Vivoactive 4S (40mm)
🏆 Battery — Vivoactive 4 (45mm)
🏆 Readability — Vivoactive 4 (45mm)
🏆 Small‑Wrist Fit — Vivoactive 4S (40mm)
🏆 Strap Choice — Vivoactive 4 (45mm)

Decision Guide

✅ Choose Vivoactive 4S (40mm) If…

  • Your wrist is slim and you prefer a watch that stays out of the way during desk work and sleep.
  • You want the same apps, payments, and safety tools as the larger model in a smaller footprint.
  • You already own 18 mm straps you like and want to keep using them.

✅ Choose Vivoactive 4 (45mm) If…

  • You value bigger text and data fields during runs, rides, or gym sets.
  • You want more margin for long GPS workouts with music.
  • You prefer 22 mm straps or already own a set you’d like to reuse.

Best Fit For Most Daily Wearers

For a broad range of buyers, the 45 mm case is the safer start. The extra screen and runtime ease daily use, especially if you glance at pace or power often or you stream playlists on long sessions. If your wrist is on the small side or you want a watch that disappears under sleeves, the 40 mm case delivers the same features in a friendlier size. You’re not trading away payments, music, safety tools, or apps either way—just comfort versus charge interval.

Use this rule of thumb: pick the size you can wear for a full week without thinking about it. If that’s the smaller case, you’ll still get Garmin Pay, on‑device music, multi‑satellite GPS, and app support. If that’s the larger one, you’ll get the same tools with more legibility and longer sessions between charges.

Sources: Garmin’s owner’s manual for battery and water rating and Garmin’s developer site for display specs. MSRP references align with U.S. launch pricing and may vary today.