Essay · Hardware

How long does data last?

Every storage medium forgets eventually. Most of the lifespans quoted online have no source. We traced them back to the standards bodies, archives and test labs, and kept only the numbers that survived.

Published 22 October 2026 · Memory Decay

There is no single answer, and the honest ones are shorter and stranger than the internet suggests. A worn-out consumer SSD only has to keep data for a year without power. Recordable CDs tested by the US standards lab lasted more than 30 years. Pressed DVD and Blu-ray films are rated at 10 to 20 years, a fraction of a pressed CD. And for the two things most people actually keep files on, USB sticks and spare hard drives, no manufacturer publishes a figure at all.

The figures that have a source

Each figure below comes from a standard, a manufacturer’s own document, an archive or a large field study. The middle column matters as much as the number: almost every figure is measured under specific conditions, usually a cool, dry room, and real life is rarely that kind.

How long data lasts on each storage medium, with what each figure measures
Medium	Best-sourced figure	What it actually measures	Source
SSD, unpowered	At least 1 year at 30°C	The minimum for a consumer drive already worn to its rated write limit. A newer drive should last longer; heat shortens it	JEDEC
SSD, unpowered (enterprise)	At least 3 months at 40°C	The same, for data-centre drives	JEDEC
Flash chips in general	10 years at under 10% wear, 1 year when fully worn	A qualification target for the memory chips, not a finished stick or card	JEDEC, via Viking
USB stick or SD card	No published figure	No maker we checked states how long its sticks or cards keep data	Manufacturers
Hard drive, running	Failures peaked at 4.25% a year at about 10 years	Annual failure rate in an always-on data-centre fleet	Backblaze
Hard drive, on a shelf	No published figure	The datasheets we checked give storage temperatures, not how long data survives	Manufacturers
Recordable CD (CD-R)	Over 30 years for every product tested	Accelerated ageing, 25°C and 50% humidity, no light	NIST and Library of Congress
Recordable DVD	Most over 30 years; 2 of 15 under 15	The same tests; results varied widely by brand	NIST and Library of Congress
Pressed CD (music)	50 to 100 years	Average, temperature and humidity effects only	Canadian Conservation Institute
Pressed DVD or Blu-ray (films)	10 to 20 years	The same rating	Canadian Conservation Institute
Recordable Blu-ray (BD-R)	5 to 10 years for most types	The same rating	Canadian Conservation Institute
M-DISC DVD	1,332 years claimed	The maker’s own extrapolation from its own tests	Millenniata
LTO tape	At least 30 years	A tape maker’s accelerated tests. Drives only read recent generations	Fujifilm, LTO Program
Cloud storage	99.999999999% durability a year	Loss from hardware failure only, not deletion or a closed account	Amazon, Google

Figures checked against each source on 19 October 2026. Ratings for discs assume recommended storage; a disc left in sunlight can fail in weeks.

The numbers people quote, traced

Search for how long any of these last and the same figures come back again and again. We followed each one back as far as it would go.

Commonly quoted storage lifespans and what the sources actually say
The claim	What we found
“An SSD loses data after a week without power”	A misreading. JEDEC’s table does reach one week, but only for a fully worn drive stored at 55°C. The headline requirement is a year at 30°C.
“Consumer SSDs keep data for a year unpowered”	That year is a minimum for a drive at the end of its rated life, not a typical figure for a new one.
“QLC lasts 1 year, TLC 3, MLC 5, SLC 10”	No standard or manufacturer source found. These figures circulate on blogs.
“USB sticks last about 10 years”	No manufacturer says this. The nearest sourced figure is a chip-level target of 10 years at low wear.
“Hard drives keep data 10 to 20 years on a shelf”	No manufacturer or archive figure found. The UK National Archives calls hard drive shelf life “notoriously hard to predict”.
“Burned DVDs only last 2 to 5 years”	Too pessimistic for good discs stored well, too optimistic for cheap ones kept badly. Most tested by NIST lasted over 30 years; a few under 15.
“DVD films last as long as CDs”	Not according to Canada’s conservation institute: 10 to 20 years for pressed DVD and Blu-ray, against 50 to 100 for pressed CD.
“M-DISC lasts 1,000 years, proven by the US military”	The 1,332-year figure is the maker’s own test of the DVD format. The Navy test circulated by vendors gives no lifespan.
“Eleven nines means your cloud files are safe”	Durability covers disks failing. Amazon says it “does not protect against accidental or malicious deletes”, and free accounts can be closed for inactivity.

The cloud forgets differently

Cloud storage is the most durable option on this page and the easiest to lose. Amazon and Google both design their storage to lose fewer than one object in a hundred billion a year. But that figure says nothing about your account. A personal Google account unused for two years can be deleted, along with everything in Drive and Photos. Microsoft closes accounts not signed into for two years, and asks you to sign into Outlook.com and OneDrive separately at least once a year. Dropbox deletes files from free accounts with no activity for 12 months, after warning emails. The disks are fine. The data still goes.

Why everything decays

Each medium forgets for its own physical reason. Flash memory, in SSDs, USB sticks and SD cards, stores bits as electrical charge trapped in tiny cells, which slowly leaks away, faster when it is warm and faster as the cells wear out. Hard drives store bits magnetically, which is stable, but a drive is a machine, and machines fail. Recordable discs hold data in a layer of dye that breaks down with heat, humidity and light. Tape lasts, but the drives that read it go out of production: an LTO-9 drive reads only LTO-8 and LTO-9 tapes. And cloud data lives on someone else’s terms. The same pattern runs through the web, where a quarter of the links from 2014 no longer work.

How to keep data for decades

Archivists don’t trust any single medium, and their advice is consistent:

Keep three copies, on at least two kinds of storage, with one somewhere else. The Digital Preservation Coalition recommends at least three complete copies, not all in one place, and the UK National Archives advises mixing storage technologies.
Move everything to new storage every three to five years. That is the National Archives’ guidance, and it beats every lifespan in the table above.
Check the copies. Open the files, or compare checksums. A backup you have never restored from is a hope, not a backup.
Don’t leave an SSD or USB stick in a drawer as the only copy. Flash keeps data longest when it is cool and gets powered on now and then.
Log into cloud accounts you rely on at least once a year, so they are never closed for inactivity.

Method and limits

We started from the lifespans most often quoted online for each medium and traced each one to its origin, keeping only figures from standards bodies, manufacturers’ own documents, national archives, conservation institutes and large field studies. Every figure and quote was checked against its source on 19 October 2026. Some sources are old: the NIST disc tests used products bought around 2005, and the JEDEC figures come from a 2010 presentation of a standard that has since been revised. The current revision is not publicly available, so we could not confirm whether its figures have changed. Lifespans for discs and flash are statistical, so an individual disc or drive can fail much sooner.

Questions people ask

How long does data last on a hard drive?+

No manufacturer publishes how long data lasts on an unpowered hard drive, and the UK National Archives calls their shelf life “notoriously hard to predict”. For drives in use, Backblaze’s data-centre fleet saw failure rates peak at 4.25% a year at about 10 years.

How long does data last on an SSD without power?+

The JEDEC standard requires a consumer SSD worn to its rated write limit to keep data for at least a year at 30°C. A newer drive should last longer, and heat shortens it: every five degrees warmer roughly halves the time.

How long does data last on a USB stick?+

No manufacturer we checked publishes a figure. The flash chips inside are qualified to a target of 10 years when lightly used and one year when worn out, but that is not a promise about any finished stick.

How long do CDs and DVDs last?+

It depends on the type. Canada’s conservation institute rates the best recordable CDs at over 100 years, pressed music CDs at 50 to 100, pressed DVD and Blu-ray films at 10 to 20, and some recordable Blu-ray and DVD types at 5 to 10. Sunlight can ruin a disc in weeks.

Is cloud storage safe forever?+

The storage itself is very durable, but accounts are not permanent. Google can delete personal accounts unused for two years, Microsoft closes accounts not signed into for two years, and Dropbox deletes files from free accounts inactive for 12 months.

What is the best way to store data long term?+

Keep at least three copies, on more than one kind of storage, with one in a different place, and move everything to new storage every three to five years, as the UK National Archives advises. Check that the copies still open.