How to Change CID on SD Card?

Some devices lock SD cards based on CID, blocking access even when the data is intact. A fixed CID becomes a roadblock if you’re trying to clone, repurpose, or reuse cards across systems.
Changing the CID can bypass hardware restrictions, enable cloning for kiosks or arcade machines, and allow custom ID tagging for deployment. However, most SD cards don’t support this natively, and Windows lacks built-in tools for the job.
In this guide, you will see how to change the CID on compatible SD cards using specific hardware and software on Windows. You’ll learn to read, backup, modify, and rewrite CID values safely, step by step, without bricking your card.

What Is an SD Card CID and Why Change It?

The CID is a factory‑burned identifier on every SD card. It holds the manufacturer ID, OEM ID, product name, revision, serial number, manufacturing date, and CRC. This 16‑byte string ensures each card is unique. Most cards lock this value to prevent fraud or cloning.
A non-changeable CID can block device compatibility tests, stop cloned card setups, or prevent custom labelling for apps that rely on unique IDs. Some devices check the CID before granting write access. Other users clone cards for batch setups in kiosks or arcade machines. Developers may need custom branding when distributing SD cards with proprietary firmware.
Changing the CID opens these possibilities. You can clone a master card for multiple devices. bypass device locks tied to original cards. You can assign your identifier to each card in a fleet. This step requires a “CID changeable SD card” model. Verify your card supports rewritable CID before proceeding.

Prerequisites and Tools You’ll Need

Before starting, ensure your SD card model explicitly supports CID rewriting. The following tools and conditions are required:

Recommended SD Cards for CID Rewriting

Not all SD cards support CID rewriting, even if they share the same brand or model name. Below is a list of tested cards and their compatibility:

Always test one card before bulk ordering — even minor revisions can change compatibility.

How to Read Your SD Card’s CID on Windows?

1: Insert and Open the SD Card

1. Insert your SD card into the reader. Plug it into your PC.
2. Right‑click the Start button and choose Command Prompt (Admin) or PowerShell (Admin).

2: Fetch the Raw CID

1. In the elevated shell, run: wmic diskdrive get Model, DeviceID
2. Identify your card’s device path (e.g., \\.\PhysicalDrive2).
3. Use a tool like sdptool or win32diskimager to read CID: sdptool read-cid \\.\PhysicalDrive2
4. Or open HxD, select Extras → Open disk, choose the PhysicalDrive, and read the first 16 bytes.

3: Interpret the Fields

The raw hex might look like 03534453553038478033012A2B00F5.
Break it into segments:

Change CID on SD Card: Step‑by‑Step Guide

Step 1 – Backup Original CID

Open your CID tool in Admin mode. Read the raw CID exactly as above. Paste it into a text file named original-cid.txt. Save that file in a safe folder.

Step 2 – Prepare Custom CID

Decide on your new CID. It must follow the format: 16 bytes in hex. Maintain valid manufacturer and OEM IDs if devices check those. You can manually assemble a hex string in a text editor or use an online “custom cid sd card” generator. Ensure no spaces or non‑hex characters.
For example: 0353445355303831323304567890AB12

Step 3 – Flashing the New CID

Launch your CID‑writer tool (e.g., sdptool or a dedicated GUI) as Administrator. Select the correct PhysicalDrive. In the CID field, paste your new 16‑byte string. Double‑check each character. Click “Write CID” or run:
sdptool write-cid \\.\PhysicalDrive2 0353445355303831323304567890AB12
Wait until the tool confirms success. Do not remove the card mid‑write.

Step 4 – Verify the Change

Re‑read the CID using the same command or tool from section four. Compare the output to your new string. They must match exactly. If they don’t, repeat the writing step. Only use on cards that advertise CID rewrite support. A failed attempt on a locked card can render it unusable.

Troubleshooting Common Issues

Write Errors

when you see a write‑protected or failed command, your reader may lack CID rewrite support. Try a different USB reader known to work with CID tools.

Unsupported Cards

Most consumer cards lock CID. If your tool reports “unsupported” or “invalid command,” switch to a specialty card model that lists “CID rewritable.”

Permission Denied

Ensure to run your tool as Administrator. Right‑click the executable and choose “Run as admin.” Temporarily turn off antivirus or Windows Defender real‑time protection.

Verification Mismatch

If the read‑back string doesn’t match your input, check your hex for typos. Confirm byte order. Try rewriting after a fresh reboot of your PC and card reader.

Tips for Successful CID Rewriting

Once you’ve mastered the basics, these advanced tips and best practices will help ensure reliable, repeatable CID rewrites without risking your hardware.

1. Use test cards first – Avoid risking important cards until your setup is verified.
2. Stick to known models – Use confirmed CID-writable cards like older Samsung EVO+ or industrial Transcend.
3. Avoid internal readers – Use USB readers with proven CID access (e.g., Alcor Micro, Realtek with patched firmware).
4. Physically label cards – Mark cards with partial CID or unique ID after rewriting.
5. Encrypt CID logs – Store original and new CIDs in encrypted files or password managers.
6. Check byte order – Match the tool’s endianness to avoid incorrect writes.
7. Reboot before flashing – Clears potential conflicts with drivers or memory.
8. Disable antivirus temporarily – Prevents interference with raw disk tools.
9. Log every write, track the tool used, result, and timestamp for each CID change.

Optimizing and Safeguarding Your SD Cards

After a CID change, format your card in exFAT or FAT32 for best performance. Enable the write‑protection switch on the card if you don’t want to rewrite it again. Set up BitLocker To Go or VeraCrypt to encrypt sensitive projects’ data. Regularly test your rewritten cards in target devices to confirm stability. Keep firmware and drivers updated on your PC to avoid future compatibility issues.

Conclusion

Changing the CID on an SD card opens up advanced use cases like cloning master cards, bypassing device locks, or managing large deployments with custom identifiers. With the proper hardware, software, and a tested process, CID rewriting on Windows becomes a precise, repeatable task, not a guessing game. Just remember: always verify compatibility before flashing, back up the original CID, and never assume a card is writable until it’s proven.
For tools, verified CID-compatible SD cards, and reliable card readers tested by the community, check out MRT3C, which stocks hardware that works for low-level access. Get your setup right the first time.

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