Every file on your SSD, phone or memory card sits on NAND flash. Power off the device and the data is still there. That's the whole point of it. Inside the chip, billions of tiny cells hold your data by trapping electrons, and in 2026 AI data centers have been buying up so much of this memory that SSD prices went up quite a lot.
We'll go over how NAND works and how it stacks up against other memory. After that comes the part most people actually ask about, which is how long data lasts on it, plus why it costs more this year.
What Is NAND Flash?
In simple terms, it's non volatile memory. It doesn't need power to hold on to data. The name is taken from the NOT AND logic gate. Its cells are wired in a chain, one after the other, in a similar way to the transistors in that gate, and this chain layout lets the cells be packed very tightly. That's how a small chip ends up with so much storage.
Toshiba (the company is now called Kioxia) built the first NAND flash memory back in 1987. These days every SSD you can buy uses it. So when a listing says "NAND SSD", it isn't some special kind of drive. The word only refers to the chips inside.
How Does NAND Flash Store Data?
1. Trapping Electrons in a Cell
Picture each cell as a small sealed room. Its door is a thin layer of insulation. When a high voltage is applied, electrons get pushed through that door into a storage layer, and they stay stuck there once the voltage is gone. Reading works the other way around. The chip sends a small voltage and checks if current can flow past the cell. A full room blocks it. A nearly empty room lets it pass, and the chip reads that as a 0 or a 1.
2. Pages, Blocks and the Controller
Data gets written in small units called pages. Erasing is different, though, as NAND can only erase whole blocks, and one block can hold hundreds of pages. If one page needs to change, the drive writes the new version in a fresh spot and then marks the old copy as stale. Keeping track of all that is the controller's job. It also spreads writes over the cells so they wear more evenly. Stale blocks get cleared in the background.
It explains why a nearly full SSD can feel slower. There are fewer empty blocks left, so the controller has to copy and erase a lot more before it can write anything. Try to leave 10% to 20% of the drive free. Keep TRIM switched on too.
NAND vs DRAM vs NOR Flash
A computer uses a few kinds of memory chips, and they don't do the same job. IBM has a good overview, but the short version is below.
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Memory
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Keeps data with power off?
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Speed
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Cost per GB
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Typical use
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NAND flash
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Yes
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Fast
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Low
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SSDs, phones, cards, USB drives
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DRAM
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No
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Fastest
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High
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System RAM, graphics memory
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NOR flash
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Yes
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Fast reads, slow writes
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Highest
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BIOS and firmware chips
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Hard drive
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Yes
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Slowest
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Lowest
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Bulk and archive storage
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Where NOR does well is reading single bytes fast. The small firmware chip that starts up your PC is a good fit for that. Its code gets read on every boot and almost never rewritten. NAND handles pretty much everything else.
What Is NAND Flash Used For?
If a device stores files and has no moving parts, it most likely uses NAND:
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SSDs in laptops, desktops, game consoles and servers.
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Phones and tablets, with soldered UFS or eMMC storage.
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Memory cards for cameras, drones, dashcams and handheld consoles.
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USB flash drives, and portable SSDs too.
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Cars use it for infotainment, maps and driver assist data.
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In data centers, enterprise SSDs feed AI and cloud services.
Not every device needs the same thing from it. A dashcam cares about endurance, while a USB stick is mostly about price. If you're buying cards, our list of SD and microSD card manufacturers compares the main brands.
SLC, MLC, TLC and QLC at a Glance
One NAND cell can hold anywhere from one to four bits. It does this by storing different amounts of charge. SLC holds 1 bit and MLC holds 2. TLC holds 3, and QLC holds 4. Packing in more bits makes storage cheaper per GB, but the cell wears out sooner. With four bits, the charge levels sit very close to each other, and as the cell ages they get harder to tell apart. Most SSDs sold now are TLC. QLC tends to show up in big drives that are mostly read from.
How Long Does Data Last on NAND Flash?
Over time, the trapped electrons slowly leak out. This means a drive left unplugged can lose data. The speed of that loss comes down to how worn the cells are. Temperature matters as well, and a warm drive loses charge faster.
JEDEC's retention rules set a minimum. A client SSD that has used up its rated endurance still has to keep data for one year without power at 30°C. For an enterprise SSD the bar is three months at 40°C. A new drive, or one that's lightly used, will hold data far longer than that. Often it's several years. Heat and heavy wear cut that down.
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⚠ Storing data on an unplugged drive?
Plug the drive in every few months and leave it connected for a bit, so the controller has time to refresh weak cells. Store it in a cool, dry place. If the files really matter, keep a second copy on another drive or in the cloud.
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Want to know if a drive is wearing out? Our guide to SSD lifespan and warning signs covers what to look for.
Why Is NAND Flash So Expensive in 2026?
Many buyers have watched an SSD that cost about $129 a year ago climb to around $400. The cause is AI. Data centers running AI services buy enterprise SSDs by the rack, and servers now account for more than 40% of NAND demand, according to TrendForce.
Makers haven't added much new capacity, so prices rose every quarter of 2026. NAND makers earned a record $46 billion in revenue in Q1 2026, based on Counterpoint Research data. Supply isn't expected to get close to balance until the second half of 2027, at least going by most forecasts.
Who Makes NAND Flash?
Five groups make nearly all of the world's NAND: Samsung, SK Hynix with its Solidigm unit, Kioxia with SanDisk, Micron and China's YMTC. Drive brands buy these chips and add their own controllers and firmware. Cheap knockoff drives have shipped with recycled or relabeled NAND, so buy from known brands and check reviews before trusting a deal that looks too good.
See who turns these chips into drives in our list of top internal SSD manufacturers. Digiera builds SSDs, memory cards and USB drives for OEM buyers with the NAND source stated up front, and you can request a quote on Digiera's SSD manufacturing page.
FAQs
What is the difference between a NAND SSD and a normal SSD?
None, really. All SSDs store data on NAND flash, and putting "NAND" in a product name just points to the chips. What actually sets drives apart is the interface, the controller and the cell type, and our NVMe vs SATA SSD guide goes into those.
Why is NAND flash so expensive right now?
Mainly because of AI. Data centers have been buying enterprise SSDs faster than makers can add new capacity, which caused a supply shortfall in 2026. TrendForce still expects NAND contract prices to go up 15% to 20% in the fourth quarter.
Is NAND flash the same as RAM?
No, they're different. RAM uses DRAM, and it's faster, but it forgets everything once the power is off. NAND is slower and keeps your files without power. That's why a computer uses DRAM for the work it's doing right now and NAND for storing things.
Does an SSD lose data if left unplugged?
Yes, it can, though it happens slowly. A new SSD will usually keep data for years without power. A heavily worn drive kept somewhere hot could start losing data within a year, so it helps to plug it in every few months and let the controller refresh the weak cells.
What does NAND stand for?
It's short for NOT AND, which is a basic logic gate. Flash memory got that name because its cells are wired in series, the same way the transistors in that gate are arranged. This layout is also why NAND can fit so many cells in one small chip.
Who invented NAND flash memory?
Fujio Masuoka and his team at Toshiba came up with flash memory during the 1980s. Toshiba then produced the first NAND flash chip in 1987, and its memory business is now known as Kioxia. Early on, NAND was used in digital camera cards. Phones, music players and SSDs came later.
Is NOR flash better than NAND flash?
For storage, no. NOR can read single bytes quickly, which is useful for firmware chips. It's slow at writing, though, and it costs a lot more per GB. NAND is denser and cheaper, and that's why almost all files end up on it.
How long does NAND flash last?
That depends on the cell type and on how much data you write. A typical TLC SSD is rated for hundreds of terabytes written. For normal home or office use, that works out to many years before the cells wear out.
