Micro SIM vs Nano SIM: which one to choose for your smartphone?

What is a SIM card?

Let’s start with the basics. The SIM card, “Subscriber Identity Module,” is a small chip that, when inserted into different types of mobile devices, allows connection to the mobile network of the operator that produced the SIM.

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What is a SIM card used for?

Do you really know all the functions of a SIM, beyond the most obvious one related to your number?
Let’s discover them together:

• It connects you to the mobile network: thanks to the SIM card, linked to a mobile network operator, you can make calls, send messages, and browse online.
• It stores data: the SIM contains some essential information, such as:
  – IMSI (International Mobile Subscriber Identity): a number that identifies a user on the mobile network… that is, your number!
  – ICCID (Integrated Circuit Card Identifier): the unique code that identifies the SIM card.

Types of SIM cards and sizes

While smartphones are getting larger, SIM cards are getting smaller! But as we know, size doesn’t matter; the functionalities remain the same!

Differences between SIM cards

As mentioned earlier, the size of the SIM does not affect its functionalities or the quality of the connection. It is simply an evolution driven by the potential of new technologies and the needs of smartphones over time.

• Mini SIM (2FF): Until , it was the standard SIM for mobile phones, a nostalgic memory for Millennials.
• Micro SIM (3FF): It appeared alongside first-generation smartphones, smaller than the Mini SIM but with the same “base.” Some operators provided a Mini SIM format pre-punched to become a Micro SIM when changing phones, while others who didn’t have this option could simply “cut” their Mini SIM to make it a Micro SIM.
• Nano SIM (4FF): The smallest on the market, which must be purchased as it is! It’s not possible to cut a Micro SIM to make it a Nano SIM, as its thickness (0.67mm) is less than that of a Micro SIM (0.76mm).

Advantages of the Nano SIM

It is simply the SIM suited for modern smartphones, which do not have a slot large enough for Micro SIMs. Additionally, the reduced size of the Nano SIM helps save plastic… but be careful when handling it, as it is very delicate!

If you’ve purchased a new smartphone and are still using a Micro SIM, you can request a replacement with a Nano SIM from your mobile operator.

eSIM: the digital SIM!

As we mentioned, SIM cards are getting smaller… until they disappear!
The eSIM, “Embedded SIM,” is a virtual SIM whose technology is integrated into the latest generation smartphones.

Advantages of eSIM

• No physical card: the eSIM doesn’t require a physical support, it is activated digitally through the QR-CODE provided by the mobile operator.
• Flexibility: you can change your operator with a click, without having to swap the card. You can install multiple eSIMs on your device at the same time (but only activate one at a time).
• Increasing compatibility: more and more smartphones, tablets, and smartwatches support eSIM technology.

eSIM.sm: the best choice for travelers!

If you love to travel, the virtual SIMs from www.esim.sm are the best solution for you, allowing you to connect to the internet in over 190 countries worldwide, without having to purchase a local physical SIM and without worrying about roaming costs.

Why choose eSIM.sm?

• Offer: On our portal, you can find one of the largest varieties of plans by country. This way, you can choose and pay based on your actual needs.
• Simplicity: Our eSIMs are installed in just over a minute, thanks to the QR-CODE you’ll receive via immediately after purchase.
• Support: Our customer service is available 24/7, in all languages.

But it doesn’t end here! Our list of compatible devices is growing every day! Remember to always check your smartphone’s compatibility before proceeding with the purchase.

How to choose the right SIM for you?

To choose the right SIM, you need to consider these factors:

• Smartphone compatibility: This applies not only to our eSIMs but to all types of SIMs, as different models support different types of SIMs. Generally, if you buy a modern smartphone, you will need to use a Nano SIM.
• If you travel often: Consider purchasing eSIMs for your destinations, so you don’t have to change your SIM card frequently (risking losing it) and reduce the plastic waste associated with using temporary SIM cards in the different countries you visit.

In conclusion, choosing the right SIM depends on the mobile it will be used in and any travel or international connection needs.

The number of IoT devices is growing rapidly worldwide. SIM cards are changing too. In the past, people used different types of SIM cards (like Mini/Nano SIM). Now, some devices use SIM cards soldered to the motherboard (MFF2 SIM). There is also a new type called eSIM, which can be set up remotely. Many device makers and customers ask: Which SIM is best for my device?

This article will explain the differences between Nano SIM, MFF2 SIM, and eSIM. You will learn their pros, uses, and how they work in real devices. We will also share examples from Minew Cellular products. This will help your team give better advice to customers.

Understanding of Different Types of SIM Cards

Nano SIM

Nano SIM is the most widely used removable SIM card today. Its small size and wide compatibility make it a top choice for many devices.

Key Features:

• Size: 12mm x 9mm (about 40% smaller than older Micro SIM cards)
• Common Uses: Smartphones, tablets, IoT devices (like smartwatches or trackers), and prototype testing.
• Flexibility: Users can easily swap the SIM card between devices. For example, you can take it out of an old and put it into a new one.
• Reliability: Physical insertion ensures stable network connections in most environments.

Why It’s Popular?

Nano SIM works with almost all consumer electronics. Its standard design reduces manufacturing costs. It is also easy to test new devices during development – engineers can quickly replace SIM cards without special tools.

Limitations:

• Requires a SIM tray slot, which takes up device space.
• Not ideal for devices exposed to water, dust, or vibrations (e.g., industrial sensors).

MFF2 SIM

The MFF2 SIM is soldered directly onto a device’s motherboard during manufacturing. Unlike removable SIM cards, it cannot be replaced after installation.

Key Features:

• Size: 6mm x 5mm (50% smaller than Nano SIM, ideal for ultra-compact devices).
• Common Uses: Smart wearables (e.g., fitness bands), asset trackers, industrial equipment (like factory sensors or security cameras), and devices requiring anti-tampering features.
• Anti-Tamper Design: Once welded, it resists physical removal or tampering. This makes it perfect for security-focused applications.
• Durability: Withstands harsh conditions like extreme temperatures, vibrations, and moisture.
• Automation-Friendly: Fits seamlessly into automated production lines, reducing assembly time and human errors.

Why Choose MFF2?

This SIM type saves critical space in tiny devices. For example, a smart medical patch can’t fit a Nano SIM slot. Its permanent installation also prevents theft or misuse in public devices (e.g., shared bikes). Manufacturers like Minew use MFF2 SIMs in GPS trackers to ensure reliability in rugged environments.

Limitations:

• No user replacement – if the SIM fails, the entire device may need repairs.
• Higher upfront cost for equipment and specialized production processes.

eSIM

eSIM is a SIM chip built into devices that can be programmed remotely. Unlike traditional SIM cards, it uses over-the-air (OTA) updates to switch carrier profiles without physical replacement.

Key Features:

• No Physical Card: No SIM slot needed – saves space for slimmer designs (e.g., foldable phones).
• Remote Management: Users can switch carriers or plans via software. For example, travelers can buy a local data plan without buying a new SIM.
• Global Flexibility: Supports multiple carrier profiles, ideal for devices used across countries (e.g., logistics trackers or connected cars).
• Standard Compliance: Follows GSMA SGP.31/32 standards, ensuring compatibility with major carriers like Vodafone and AT&T.

Why Choose eSIM?

It simplifies device design and logistics. A smart thermostat using eSIM can activate service automatically after installation. Minew’s eSIM-enabled sensors allow customers to manage global deployments from one platform. Car manufacturers also use eSIMs to provide connected car services without regional SIM restrictions.

Limitations:

• Requires carrier support for remote provisioning (not all operators offer this).
• Device must have eSIM hardware pre-installed, limiting retrofitting options.

What Are the Differences of Several Types of SIM Cards

Feature Nano SIM (Removable) MFF2 SIM eSIM Removable Yes No No Installation Method Manual Insertion SMT Mounting SMT Mounting Remote Profile Provisioning No No Yes Development Cost Almost none Almost none High (requires carrier coordination) Data Cost Low Low High Security Easy to replace High High Production Process Compatibility Requires manual insertion Syncs with SMT process Same as MFF2 SIM Recommended Use Cases Replaceable devices requiring maintenance Space-limited/tamper-proof devices Smart homes, multi-device sharing, or scenarios requiring carrier switching

All three SIM types can work worldwide. But Nano SIM and MFF2 SIM need extra support:

• You must use a global roaming plan, or
• Choose a virtual carrier plan that already covers multiple countries.

And eSIM works differently. It uses an eUICC platform. This platform lets you add or switch carriers remotely. No physical changes are needed.

For more information, please visit What's a Nano Sim Card.

How to Choose From Different Types of SIM Cards

Here are some tips that can help you choose the right types of Sim cards:

If your customer wants to replace SIM cards easily (for device testing or switching carriers), Nano SIM is recommend:

• Users can swap cards manually.
• Best for devices needing frequent updates or trials.

If the device is for long-term use (anti-tamper design + mass production), MFF2 SIM is recommend:

• Soldered to the board – no physical removal.
• Works perfectly with automated SMT assembly lines.
• Reduces manual labor and errors.

If the device needs global coverage or remote carrier switching, eSIM is the solution (but costs more):

• Uses eUICC platforms to manage carriers remotely.
• Requires partnerships with eSIM service providers.

Two Key Standards to Judge eSIM

To confirm if a device uses real eSIM (not a soldered SIM), check these two requirements:

1. Does It Follow GSMA eUICC Standards?
   1. Real eSIM must use an eUICC platform.
   2. This lets you download and manage carrier profiles remotely (via servers like SM-DP+).
2. Can It Switch Carriers Remotely?
   1. The device should automatically switch to local networks when used in different countries.
   2. Example: A tracker in Germany connects to Deutsche Telekom, then switches to Verizon when shipped to the US.

Important: Only devices that meet both requirements are true eSIM. If not, it’s just a soldered SIM card.

Benefits of SIM Cards for IoT Devices:

1. Wide Device Compatibility

SIM cards have been the industry standard for decades, ensuring seamless compatibility with most IoT devices.

Nano SIM: Works with smartphones, tablets, and legacy IoT devices (e.g., smart meters, GPS trackers).

MFF2 SIM: Designed for compact devices without SIM slots (e.g., wearables, industrial sensors).

eSIM: Requires eUICC-enabled hardware but is becoming common in newer devices (e.g., connected cars, smart cameras).

2. Global Connectivity

Nano SIM & MFF2 SIM: Pair with global roaming plans or multi-country virtual operators.

eSIM: Automatically switches to local carriers via remote profiles (e.g., a logistics tracker in Japan uses SoftBank, then switches to T-Mobile in the U.S.).

3. Easy Scalability

Nano SIM: Swap cards manually for testing or upgrades (e.g., replace a SIM in a prototype device).

eSIM: Update thousands of devices remotely (e.g., deploy new data plans to smart city sensors via software).

4. Strong Security

MFF2 SIM: Tamper-proof design for public devices (e.g., prevents SIM theft in shared bikes).

eSIM: Encrypted carrier profiles block unauthorized access (e.g., protects medical IoT devices from hacking).

5. Cost Efficiency

MFF2 SIM: Reduces assembly costs through automated SMT production (e.g., no manual SIM insertion).

eSIM: Avoid roaming fees by activating local profiles (e.g., a smart thermostat uses cheaper regional data plans).

6. Durability

MFF2 SIM: Built to withstand extreme conditions (e.g., factory vibrations, outdoor weather).

eSIM: No physical card to damage (e.g., ideal for ruggedized field equipment).

Minew’s SIM Card Strategy

Minew uses Nano SIM and MFF2 SIM flexibly across different scenarios:

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Nano SIM (Removable)

• Current Usage: The most widely adopted SIM type.
• Best For:
  • Prototype testing and pilot deployments.
  • Customers needing post-deployment SIM replacement (e.g., field-upgradable devices).
• Advantages:
  • Universal compatibility.
  • Easy to source and replace.
  • Our default option for most customers.

MFF2 SIM (Embedded)

• Best For:
  • Tamper-proof, long-term deployments.
  • Mass-produced devices requiring automated assembly.
• Ideal Scenarios:
  • Disposable trackers (e.g., logistics tags).
  • Cold chain monitoring tags (no SIM replacement needed).

Custom Solutions

• Minew offers flexible SIM strategies. We can switch between Nano SIM and MFF2 SIM based on your project needs.

Conclusion