Field manual / Memory

A practical guide to numeric array memory

A packed numeric array has a predictable payload size based on element width.

Element count compared with the result of Numeric Array Memory; the example conditions stay fixed
Figure 1. Calculated scenarios for numeric array memory. The highlighted point uses the example input. Lines connect sampled points and do not imply valid fractional counts.

Start with the relationship

The question this tool answers is specific: given element count, bytes per element, what value follows from the stated model? The result is expressed in MiB. The calculation below makes that relationship visible, so the answer can be checked independently instead of accepted as an unexplained number.

element count × bytes per element

Write down whether a size uses decimal or binary prefixes and whether a rate counts bits or bytes. Compare the same system boundary on both sides of a performance calculation. Measured throughput is usually a more useful planning input than the maximum number on a product label.

A worked example

Use the following values as a reproducible starting point. They are illustrative inputs, not measurements of your situation or a recommendation for a particular project. The calculator opens with the same values, making it possible to compare a manual calculation with the on-screen answer.

InputExample valueUnit
Element count1,000,000count
Bytes per element8bytes

Substitute these quantities into the displayed relationship: element count = 1,000,000 count; bytes per element = 8 bytes. Carry out the operations before rounding the final value. This gives 7.629395 MiB. The number is a result for this particular set of inputs; changing the measurement basis or the conditions can change its practical meaning.

What changes when an input changes?

In the illustrated range, changing element count from 600,000 to 1,400,000 count moves the result from 4.577637 to 10.681152 MiB. The output increases between those endpoints. The table gives intermediate samples so you can see whether the response is smooth, stepped or nonmonotonic; the endpoints alone do not establish that behaviour.

Every other input keeps the value shown in the example table. This controlled comparison isolates one relationship at a time. For a real decision, try a lower, central and higher plausible input instead of treating an uncertain measurement as perfectly exact.

Element count (count)Result (MiB)
600,0004.577637
800,0006.103516
1,000,0007.629395
1,200,0009.155273
1,400,00010.681152

The assumption that matters

General object arrays may also contain pointers, headers and allocation overhead.

A valid numerical result only means the entered values can be evaluated by this formula. It does not confirm that the formula describes every feature of the real situation. Read the unit labels, check the measurement method and keep the specific limitation above with the result when sharing it.

Use the result in your own work

Open the calculator, replace the example values and select Calculate. The result is evaluated on your device. Reset example restores this article's scenario, while Copy result keeps the quantity and unit together. If an input is outside the model's allowed range, correct it before interpreting the output.

Keep more digits during a chain of calculations than you show in a finished note. Displayed values are rounded for readability; extra decimals do not make a rough measurement more accurate. When your decision depends on a tight tolerance, compare the original measurements and assumptions before relying on the last displayed digit.

Open Numeric Array Memory

Further reading & method notes

NIST — units, prefixes and measurement conventions provides background for this subject. This article's numerical examples and chart were calculated from the formula shown above. See the editorial policy for how this collection presents assumptions and corrections.

Keep exploring