eSIM Data Plans

Do I need two separate eSIMs for my smartphone and smartwatch?

You only need two eSIMs if your smartwatch uses its own data plan. learn how eSIM sharing works and how to connect both devices.

In most cases, yes. You’ll need a separate eSIM for your smartwatch if you want it to work independently: make calls, use data, or stream music without your phone nearby.

However, some carriers let you share one eSIM plan across both devices, so your smartwatch mirrors your phone number and data plan. Whether you need one or two eSIMs depends on your device model, carrier, and how you use your smartwatch.

In this guide, we’ll explain how eSIMs work on phones and smartwatches, when you need separate plans, and what to check before setting them up.

In this article

What is an eSIM?

An embedded Subscriber Identity Module, or eSIM, is a digital SIM card that’s built directly into your device. Here are some of the things people love about eSIMs

No swapping cards: Activate new plans in seconds, directly from your phone or watch.
Ideal for travel: Connect to local networks abroad without buying a physical SIM.
Multiple profiles: Store several plans on one device and switch as needed.
Works across devices: Modern smartphones and smartwatches now use eSIMs to stay connected, independently or together.

How eSIMs work on smartphones

Your smartphone acts as the main connection hub for all your devices, including your smartwatch.
When you install an eSIM on your phone, it gives you mobile data, calling, and hotspot access. Some carriers even let your smartwatch share that same eSIM plan, so both devices stay connected on the same number.

How it typically works:

Check if your phone is unlocked. If not, learn how to unlock an eSIM on iPhone.
You activate an eSIM on your phone by scanning a QR code or using your carrier’s app.
The same carrier can “mirror” that plan to your smartwatch (if supported), linking the two devices under one subscription.
If your smartwatch uses a different network or needs its own data plan, you’ll need a separate eSIM.

iPhones and Android devices handle this differently. For example, Apple calls it “Family Setup” when setting up a watch with its own plan, while Samsung uses “NumberSync.” Always check your carrier’s smartwatch support page before buying an eSIM.

💡Info: Do you already have your eSIM and it’s not working? Don’t panic, check these tips to solve your issue!

Smartwatches and eSIMs

Smartwatches with an eSIM can make and receive calls, send texts, and use data without needing to stay connected to your phone. This raises the central question: Does a smartwatch need its own eSIM?

In most cases, yes. If your smartwatch supports cellular connectivity, it usually needs a separate eSIM from your smartphone.

Cellular smartwatches are designed to function independently, unlike Wi-Fi-only models that rely on your phone’s Bluetooth connection.

Here’s how it works:

Your smartwatch connects directly to the mobile network through its own eSIM.
This allows you to make calls, send messages, use GPS, or stream music without your phone nearby.
Some carriers offer linked plans, letting your smartwatch share your phone number and data — but this depends entirely on the network provider.

If your smartwatch supports eSIM technology, check your device’s settings or your carrier’s smartwatch page to confirm whether plan sharing or independent activation is available in your region.

How do I buy an eSIM?

Buying an eSIM is simple and can usually be done directly from your carrier or an international provider.

💡 If you want a local eSIM: Many carriers today allow you to replace your SIM to an eSIM and keep the existing plan.

💡 If you want an international eSIM: Choose a global provider like Holafly to stay connected while traveling. These plans are digital, easy to activate, and designed for short-term data use abroad.

In this case, the process is simple:

Choose your destination.
Select an eSIM data plan that fits your usage (the number of days for unlimited data).
Scan the QR code you receive after purchase.
Follow your device’s setup instructions to activate your eSIM.

If you prefer a flexible option, Holafly offers both prepaid travel eSIMs and Holafly Plans — a monthly postpaid plan that keeps you connected in over 170 destinations. Both can be activated in minutes by scanning a QR code, so you’re online instantly, whether you’re at home or abroad.

Final answer: Do you need two eSIMs?

Whether you need one or two eSIMs depends on how you use your smartwatch.

💡 If you want your smartwatch to work on its own: To make calls, stream music, or use apps without your phone nearby, you’ll need a separate eSIM. This gives your watch its own mobile plan and number (unless your carrier supports number sharing).

💡 If you mainly use your smartwatch as a companion device: For notifications, fitness tracking, or syncing apps, you can usually share your smartphone’s eSIM plan. In that case, your watch and phone stay connected through Bluetooth or WiFi.

You can also link your Holafly eSIM to both your phone and smartwatch if your carrier supports plan sharing, perfect for travelers who want both devices online.

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Katarina M Arsic

Senior Writer

With a background in English literature and a focus on storytelling, I’ve turned my interests in travel and technology into a career helping others stay connected abroad. Originally from Serbia, I work remotely with my husband, experiencing local cultures firsthand and bringing that perspective to my writing for Holafly. Fun fact: before focusing on content creation, I was a professional volleyball player.

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