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SIM Card Sizes, and What they Mean

Kyle Reyes
October 17, 2022

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Interested in the inner workings of your phone’s sim card? Well, you’re in luck! This article is all about SIMs. If you are looking to change providers, phones, or something related you may have come across the fact that there are, in fact, four different SIM card sizes. There are full-size SIM cards, mini SIM cards, micro SIM cards, and nano SIM cards. 

All of the above-mentioned cards are pretty small. Small enough to fit in your phones! This article will cover all the information surrounding the different sizes of SIM cards, what a SIM card is, and all the information that’s contained inside of it. 

What are all the Different SIM Card Sizes?

The chip is the same no matter the sim card size. This lets different models all take the standard chip. Image courtesy of Mint Mobile

Different phones have different SIM card sizes, generally trending towards smaller and smaller cards on newer phones. The four major SIM cards in play today are: 

  • Full-Size (standard) SIM cards at 85mm x 53mm
  • Mini SIM cards at 25mm x 15mm
  • Micro SIM cards at 15mm x 12mm 
  • Nano SIM cards at 12.3mm x 8.8mm

Full-size SIM cards have not been the standard since 1996 when the first mini SIM entered the playing field. The mini held the top spot until 2003 when Apple introduced the micro SIM with their groundbreaking iPhone 4. After that, the nano SIM entered serious circulation in 2012, and has remained that way until today! Who knows, the next scale-down might be on its way. 

The actual size of the SIM chip is exactly the same across all the different card sizes. The only difference is in the amount of plastic that surrounds the chip. As phones got smaller and smaller they didn’t have enough space for the bigger SIM card sizes, leading companies to ponder how to get their chips smaller and smaller to match the phones. 

SIM Card Size Differences

SIM cards, though they come in different sizes, all have the same meat inside. This subsection will cover the different SIM card sizes and when they came into the market. 

Standard SIM Card Size

Standard SIM cards, while the original size, have fallen out of favor long ago. They are so big (relatively speaking) that most phones don’t have the real estate to house them and are instead opting for one of their smaller cousins. 

Mini SIM Card Size

Introduced in 1996, Mini SIM cards were the next step from the standard size. Since they were smaller, they could better fit into these phones that were getting thinner and thinner. 

Micro SIM Card Size

Micro SIM cards, the next step in SIM cards, sized down once more (starting to see a pattern here?) as phones continued to develop. 

Nano SIM Cards

The current smallest SIM card, Nano SIMs are so small you almost can’t see them! They’ve been in circulation since 2013 and are standard in many of the newest phones. 

What SIM Card Size is in Your Phone? 

Nano SIM cards are in almost all phone models since 2010, but you can make double-certain by searching your specific phone model to see what size it takes. You can also remove your SIM card, but we don’t recommend doing that unless you are switching carriers or switching phones! If you must know, here’s how to remove your SIM card if you have an iPhone:

  • Look for the SIM tray on your phone. It is most likely on the right-hand side, but some older models have the SIM tray on the top of the phone. If you want, you can look online to see where the tray is for your particular model.
  • There’s a little indent in the tray that’s the perfect fit for a small tool like an unbent paperclip or if you have one, a SIM Ejector Tool.
  • A slight push at the indent will release the tray, allowing you to remove the SIM card. 

For a Samsung phone:

  • Check to see if your phone has a removable back cover, typically seen in older Samsung phones.
  • If so, the SIM is located behind the battery. Remove the back cover, remove the battery, and the SIM should be in sight.
  • If the back is sealed, check the phone’s manual to see where the tray is located. The spots vary based on the manufacturer and model of the phone.
  • Once you find it, do the same trick with the paperclip and you can remove the SIM tray once it’s been released. 

Sim Cards

SIM cards have gotten smaller and smaller because the chip itself is the same within each one. The only real change was in the amount of plastic that surrounded the cards, which was originally so because it needed to be that big. As phones evolved and got sleeker and sleeker it made sense to dispense with the extra material, leaving us with the nano-SIM, which is basically just the chip itself. 

When you are changing phones or changing SIMs, make sure to get the right size. Phones cannot take SIM cards bigger or smaller than their intended size as the housing will not fit any other size. For example, the iPhone 13 takes a nano SIM card and nothing bigger than that will fit in the card. You could, if you were really feeling it, cut the card to size yourself, but that is a high-risk low-reward path when you could just contact your provider and get a new SIM! 

What is a SIM Card? 

Sim cards should come with every phone purchased from your provider. They even give you a punchout board that allows you to pick the correct size for your phone. Don’t punch it out too soon! 

Over the years you may have come in contact with a SIM card or two as you switched phones or providers, but they most likely took a backseat to what was more exciting at the time, being, well, the new phone or the new wireless carrier. SIM cards have changed a lot over the years, too! This section will cover the ins and outs of SIM cards and what they do. 

The SIM card connects to your carrier’s networks so you are able to access data on the network. This is your calling, your texting, and your mobile internet. Alongside that, the SIM houses your International Mobile Subscriber Identity (IMSI), an ID number that informs the network about your active mobile account. There are a few other bits of data encoded on the SIM, which we will get into later. What’s awesome about the SIM card is that it can move from one phone to the next (as long as it’s the right size!) so you can transfer all of that detailed and account-specific information from the phone to your new phone as you get your next upgrade. Practically, it means you can retain your phone number and contacts even if you move to a new phone. 

What Happens to Phones Without SIM Cards? 

If a phone doesn’t have a SIM card then it isn’t connected to a phone number and it can’t connect to any mobile network. It’s a lot like a tablet. At this point, they can, however, return to form when a new SIM card is imputed into their slot. As long as it is a valid SIM card to a valid account, any phone can return to being a fully-functioning device. 

Replacing Your SIM Card

This is a common occurrence, and, fortunately, it is very easy! Following the information above you can find your SIM card tray and take out the old one and pop the new one right in its place. You should notice a bit of a notch cut into one corner of the SIM card and you should see a notch of the same profile on your SIM tray. Once you insert the SIM in the right way, the tray should slide right back in, and then you’ll be back in business. 

Switching SIM Cards

Just about everyone switches SIM cards at some point, and, if you follow the steps to switch them out it should be a breeze! But you should not switch out your SIM cards on a whim. Here are the three major reasons why you might want to switch out your SIM card. 

  • You’re switching from one phone to another on the same plan, keeping your number and other account information
  • You are switching out an old and busted SIM card for a new one because you’ve noticed some problems in your service
  • You’re switching to a new carrier entirely! 

Regardless of your reason, note that your SIM card doesn’t hold much of your phone’s data. While we’ll get to what’s stored on your SIM card in the next section, it is enough to know that your phone’s data is stored in the phone while your account data is stored in the SIM. Especially if you are changing phones or changing carriers it is important to figure out ways to back up your app data, contacts, photos, and anything else you want to keep that was on your phone. 

What’s Stored on my SIM Card?

Switching from one SIM card to the next does not affect any information that’s stored on the phone itself. Image courtesy of Mint Mobile.

At this point in the article, we’d wager you are feeling like a SIM card aficionado, but there’s one more section about SIMs before you can consider yourself a master of the card. Your SIM card stores a lot of specific data like your phone number, account info, and identification. These work to protect against theft and help a bit with security if your phone were to fall into the wrong hands. 

Information Your SIM Card Stores

Your SIM card has a lot of specific data on it. It does not hold a lot of data, and that data is not often changed. Here’s some of the most salient information stored on your SIM card:

  • Authentication Key: A string of numbers on your SIM (unique to you) that authenticates it on the network in which it is currently running 
  • Advice of Charge: An estimation of the mobile services cost for your phone
  • Local Area Identity: Identifying code that combines with your phone number and mobile country code
  • Mobile Country Code: This well-named piece of information shows the country from which you are calling
  • Service Provider Name: Put simply, it’s the name of the company from which you get your service
  • Service Dialing Number: Numbers you can dial to get information related to your mobile account
  • Unblocking Code: This is the code you need to open your phone if you put in the wrong PIN one too many times
  • Short Message Service Center: The process that delivers your text message
  • Voice-Added Services: Additional services you’ve purchased for your phone
  • Integrated Circuit Card ID: A unique number for your SIm that helps identify it. No two SIM cards can have the same number. If that ever happens it would lead to a lot of confusion. A lot.

This varies from phone to phone, but your IMEI number might also sit snugly in your SIM card. SIM cards generally store anywhere from 8 KB to 256 KB. Like we said, not a lot. For a better comparison, a gigabyte contains 1000000 kilobytes. The info stored on your SIM card is not data-intensive, rather it allows your phone to be your phone. 

Accessing Your SIM Card’s Storage

There are a few different ways to access your SIM card’s storage if you find yourself so desiring it. You can buy a SIM card reader, where you can take your SIM card out of your phone and place it in the reader, which then connects to your computer and outputs all the data stored on the card. 

On an iPhone, you can go into your settings and poke around until you see the info on your SIM card. On an android, you can go through a similar process to find the information in your phone’s settings. 

What Happens When You Take Out Your SIM Card?

Not much! Your phone turns from a smartphone to a smart device, but all the data is still there. You lose connection to your mobile data, but your phone won’t crash or factory reset, or anything scary like that. You’ll still have all your contacts and pictures and all that good stuff. While your phone will lose access to your number, it should sync right back up when you put your SIM card back into your phone. 

compare phone plans and save up to 80%

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Kyle Reyes
Kyles Reyes is a journalist from Pittsburgh, PA that specializes in the wireless industry, phone plan comparisons & advice.
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