Memory Array Size Calculator

Work out memory array size instantly with clear inputs, formula shown and shareable results.

About Memory Array Size Calculator

Array area is bit count times cell area, inflated by peripheral overhead for decoders, sense amplifiers, write drivers and control. That overhead is 25-45% for a small array and is why many small memories are far less area-efficient than a few large ones.

Formula

Memory array

bits = rows x columns; area = bits x cell area x (1 + peripheral overhead)

Worked example

With the default values below, Memory Array Size Calculator returns Total array area of 7,431.8. Change any input above and every figure here is recalculated in your browser.

Inputs used

Rows: 1,024 rows
Columns: 256 columns
Bit cell area: 0.021 µm²
Peripheral overhead: 35 %

Results

Total array area: 7,431.8 µm²
Capacity: 256.00 kbit
Bit cell array area: 5,505.0 µm²
Effective density: 35.27 Mbit/mm²

Step by step

1Values used
2Memory array
3Total array area= 7,431.8 µm²
4Capacity= 256.00 kbit
5Bit cell array area= 5,505.0 µm²
6Effective density= 35.27 Mbit/mm²

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Why is overhead so high on small arrays?

Decoders and sense amplifiers are largely fixed cost per array. A 1 kbit array can be more than half periphery.

What bit cell areas are typical?

Roughly 0.021 um2 for 7 nm SRAM, 0.027 at 10 nm and 0.04 at 14 nm. SRAM scaling has slowed markedly at recent nodes.