Flash & EEPROM Endurance Calculator — how long until it wears out

How long your flash survives at a given write rate, and how much wear levelling buys you.

Example: At 100 writes a day, this memory lasts about 35 years — 0.8 physical erases per day against 10000 available.

Inputs

Memory type

Rated cycles (optional)

From your datasheet. Leave blank to use the type's typical figure.

Writes per day

Bytes per write

Pages for wear levelling

1 means no wear levelling — every write hits the same page.

Result

Lifetime

35 years

Physical erases per day: 0.78
Total erases available: 10000
Writes before an erase: 128
Write amplification: 1×
In days: 12800

Flash erases in 2048-byte pages, so 16-byte writes can be packed 128 to a page before an erase is needed. That gives 1× write amplification — sizing lifetime from logical writes alone would overestimate it substantially.
With no wear levelling, every erase lands on the same page. Spreading writes across 8 pages would give roughly 280.4 years instead of 35.
Rated endurance is specified at room temperature. It falls at elevated temperature, and retention — how long data survives unpowered — falls faster still. A part rated for 10,000 cycles and 20 years retention at 25 °C offers considerably less of both at 85 °C.

Lifetime against write rate

Writes/day	Erases/day	Lifetime
1	0.01	3504.4 years
24	0.19	146 years
144	1.13	24.3 years
1440	11.25	2.4 years
86400	675	14.8 days

Check it against real silicon

Chiprun runs your firmware on an emulated microcontroller and hands back the UART output, so you can confirm these numbers rather than trusting them.

Chiprun docs

Formula

lifetime = endurance × wear-levelled pages / physical erases per day

Worked example

At 100 writes a day, this memory lasts about 35 years — 0.8 physical erases per day against 10000 available.

writes per page = page size / bytes per write
2048 / 16
128
Flash must erase a whole page, so small writes are packed until the page fills.
erases per day = writes per day / writes per page
100 / 128
0.78
lifetime = endurance × pages / erases per day
10000 × 1 / 0.78
12800 days (35 years)

Frequently asked questions

How many times can flash be written?

Typically 10,000 erase cycles for MCU internal flash and 100,000 for EEPROM and serial NOR — per page, not per device. The figure is for erases, not writes, which is why page size and write size matter so much.

What is write amplification?

The gap between the bytes you write and the bytes the memory actually erases. Flash erases whole pages, so updating 4 bytes in a 2 KB page can cost a full erase. Packing several small writes into one page before erasing is how firmware libraries keep the ratio down.

Does wear levelling really help that much?

Yes, essentially linearly. Spreading writes across 64 pages instead of 1 gives 64 times the erase budget. It is the single most effective change for a design that writes frequently, and it is why emulated-EEPROM libraries exist.

Does temperature affect endurance?

Considerably. Rated cycles are specified at room temperature, and both endurance and retention degrade at elevated temperature. A part rated for 10,000 cycles and 20 years of retention at 25 °C offers noticeably less of both at 85 °C.

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