QLC vs TLC: Which SSD Flash Type Should You Buy?

What is the difference between QLC and TLC?

TLC (triple-level cell) stores 3 bits per cell and must distinguish 8 voltage levels. QLC (quad-level cell) stores 4 bits and needs 16 levels. That fits about a third more data into the same number of cells. The trade-off: lower write speed after the cache and usually lower TBW.

The number of levels is 2 to the power of the bit count: 2 to the power of 3 is 8, 2 to the power of 4 is 16. Samsung's own data sheets call the 870 EVO flash "3bit MLC" and the 870 QVO flash "4bit MLC", which means TLC and QLC.

How many write cycles each cell type tolerates and what that means for lifespan is covered in our guide to SSD lifespan. This page focuses on the buying decision between QLC and TLC.

Is QLC slower than TLC?

For reads and short writes, barely: on Samsung's drives both cell types first write into a fast area called Intelligent TurboWrite. Once it is full, QLC drops sharply. Samsung quotes 80 MB/s for the 1 TB 870 QVO and 160 MB/s from 2 TB, versus 530 MB/s for the TLC 870 EVO from 1 TB.

The 2 Samsung SSDs make a rare like-for-like comparison: same form factor, same SATA interface, same MKX controller and the same peak figures of 560 MB/s read and 530 MB/s write. The difference is the flash.

Samsung 870 EVO (TLC) vs 870 QVO (QLC) per data sheet

Sources: 870 EVO data sheet, 870 QVO data sheet. Samsung measures peak figures with Intelligent TurboWrite active.

In everyday terms: installing a game or copying a few photos feels the same on QLC. Copy 200 GB of video in one go to a 1 TB QVO, though, and Samsung's figure drops to 80 MB/s, slower than many hard drives. The EVO stays at 530 MB/s from 1 TB up.

Can a QLC SSD be slower than a hard drive?

After the cache fills, small QLC drives can be. Samsung rates the 1 TB 870 QVO at 80 MB/s at that point. A NAS hard drive such as the 24 TB Seagate IronWolf Pro is rated up to 285 MB/s, an 8 TB WD Red Plus up to 215 MB/s. For random reads, every SSD stays far ahead.

Values from the Samsung 870 QVO and 870 EVO, WD Red Plus and IronWolf Pro data sheets. Seagate specifies its hard drive figure at the outer diameter (OD) of the platters, Western Digital gives a maximum.

This only matters if you write very large amounts of data in one go. For launching programs, loading games and handling many small files, even a QLC SSD is far ahead of a hard drive because it has no heads to move.

What is an SLC cache?

An SLC cache is part of the flash that temporarily stores only 1 bit per cell, which makes it fast to write. New data lands there first and is later rewritten into TLC or QLC cells. Samsung calls this Intelligent TurboWrite, SanDisk calls it nCache 4.0.

Many makers do not disclose the cache size. StorageReview describes nCache 4.0 in the WD Blue SN5100 as a pseudo-SLC cache that data is written to before it moves to the main QLC flash (StorageReview). Tom's Hardware found a pseudo-SLC cache of about 400 GB on the 2 TB Crucial P310 (Tom's Hardware, 07/17/2024).

The cache costs space: Tom's Hardware points out that 400 GB of pSLC cache occupies 1,600 GB of regular flash on the P310, because each cell in the cache holds 1 bit instead of 4. Samsung's data sheet also shows a size effect: the 1 TB 870 QVO writes only half as fast after the cache as the 2 TB and larger models.

Do QLC SSDs wear out faster than TLC?

Usually, but not always. Samsung rates the QLC 870 QVO for 360 TB written per TB of capacity and the TLC 870 EVO for 600 TB. SanDisk, on the other hand, rates the 1 TB WD Blue SN5100 with QLC for 600 TBW, the same as Samsung's 1 TB TLC drives.

TBW (terabytes written) is the amount of data the maker allows you to write within the warranty; coverage ends at the stated time or the TBW, whichever comes first. Samsung says its endurance figures comply with JEDEC's JESD218 standard. JEDEC is a standards body for the microelectronics industry, and JESD218 sets operating conditions and endurance verification requirements for SSDs (JEDEC).

TBW per TB of capacity per data sheet

Sources: Samsung data sheets for the 870 QVO, 870 EVO, 990 EVO Plus, 990 PRO, 9100 PRO, plus SanDisk's WD Blue SN5100 specs (data sheet 08/2025, also listed by StorageReview).

On the SN5100, TBW per TB falls as capacity grows: 600 TB at 1 TB, 450 TB at 2 TB and 300 TB at 4 TB. For most people, every value here lasts many years. Writing 50 GB a day adds up to about 18 TB a year, so 360 TBW would take roughly 20 years.

How much do QLC and TLC SSDs cost per TB right now?

The cheapest SSD with QLC per data sheet costs $167.99 per TB on amazon.com right now (WD Blue SN5100 1 TB), the cheapest with TLC $200.00 per TB (Samsung 990 PRO 2 TB).

SSD lines with cell type per data sheet, cheapest new offer on amazon.com, as of Oct 29, 2026 at 1:17 AM UTC

We only list lines whose data sheet names the cell type. A missing line had no new offer on amazon.com in our latest fetch. The cheapest offer may be any capacity, so per TB values mix sizes. For comparison, the TB index for all M.2 NVMe SSDs is $133.85 per TB, and for 2.5-inch SATA SSDs $122.93 per TB. Many budget SSDs do not state their cell type at all, so their data sheets cannot settle whether they use QLC or TLC.

The direct Samsung comparison: the 870 QVO costs $182.50 per TB right now (Samsung 870 QVO 8 TB), the 870 EVO $312.48 per TB (Samsung 870 EVO 4 TB). Here QLC is 41.6% cheaper per TB. Long-term SSD prices are on our SSD price history page, and the wider trend is in our guide to SSD prices.

Are there QLC NVMe SSDs?

Yes. The WD Blue SN5100 uses QLC according to SanDisk and reads at up to 7,100 MB/s over PCIe 4.0. The Crucial P310 also uses Micron QLC according to Tom's Hardware. On peak figures, these drives sit close to TLC models like the Samsung 990 EVO Plus.

We have no data sheet stating the cell type for the Crucial P310, so its values come from Tom's Hardware's review and not from the maker. It is left out of the price table above for the same reason. Peak figures apply while the fast cache has room.

How can you tell if an SSD uses QLC or TLC?

The manufacturer's data sheet is the most reliable source. Samsung states the cell type explicitly, and so does SanDisk for the WD Blue SN5100. Many other brands only say "3D NAND" without a bit count. Warranty, TBW and post-cache write speed can give hints.

1. Read the data sheet: Look for QLC, TLC, "3bit" or "4bit". If it only says "3D NAND", the cell type is unknown.
2. Compare warranty and TBW: A 3-year warranty and low TBW per TB hint at QLC, as with the 870 QVO. It is not proof: the SN5100 has QLC and a 5-year warranty.
3. Check reviews: Outlets such as Tom's Hardware and StorageReview often name the flash, as with QLC in the Crucial P310.
4. Listing titles: Sellers sometimes put QLC or TLC in the title. That is a seller claim and may be wrong.

Among the Samsung lines covered here, "QVO" means QLC, "EVO" and "PRO" mean TLC, each according to the data sheet. Other brands follow no fixed naming scheme.

Who should buy QLC and who should buy TLC?

QLC suits large game libraries, media archives and secondary drives that are read a lot and rarely hit with huge writes. TLC is the better choice for a boot drive, video editing, virtual machines and anything that writes large amounts of data regularly.

Price decides too. If a TLC SSD costs barely more per TB than a QLC one, take TLC. If QLC is clearly cheaper and the drive is mostly storage, skip the premium. For pure bulk storage, hard drives remain much cheaper per TB, see our guide SSD vs HDD.

Is QLC good enough for gaming or a PS5?

Yes, QLC is usually fine for games. Once installed, games are mostly read, and for reads QLC and TLC are close on manufacturer specs. The QLC WD Blue SN5100 reads at up to 7,100 MB/s according to SanDisk, the TLC Samsung 990 EVO Plus at up to 7,250 MB/s.

QLC slows down when installing large games once the cache fills up. Which SSDs fit a PS5 and what Sony requires is covered in our guide to the best SSD for PS5, recommended lines in our best SSD guide, and whether NVMe or SATA is enough in our guide NVMe vs SATA.

How does ratioDB classify QLC and TLC?

ratioDB only labels an SSD line QLC or TLC if the manufacturer's data sheet states the cell type. Prices are fetched from amazon.com at regular intervals and converted to price per TB, with 1 TB equal to 10^12 bytes.

We do not take cell types from listing titles because they are unverified. The table shows the cheapest new single drive per line, in any capacity. We do not run our own measurements; all technical values come from the linked data sheets. All rules are on our methodology page, and every offer is listed under M.2 NVMe SSDs and 2.5-inch SATA SSDs.