# Checking multiplication overflow

DevFeed: [Checking multiplication overflow](<https://devfeed.tech/articles/checking-multiplication-overflow-29405.md>)

Original publisher: [Read original article](<https://lemire.me/blog/2026/05/06/checking-multiplication-overflow/>)

Author: Daniel Lemire

Published: 2026-05-06T20:15:20Z

Content type: article

Language: en

Sources: [Daniel Lemire](<https://devfeed.tech/sources/daniel-lemire.md>)

Topics: [C](<https://devfeed.tech/topics/c.md>), [C++](<https://devfeed.tech/topics/c-plus-plus.md>), [Compiler](<https://devfeed.tech/topics/compiler.md>), [Go Language](<https://devfeed.tech/topics/go-language.md>)

Tags: [c](<https://devfeed.tech/tags/c.md>), [c-plus-plus](<https://devfeed.tech/tags/c-plus-plus.md>), [compiler](<https://devfeed.tech/tags/compiler.md>), [go](<https://devfeed.tech/tags/go.md>)

## AI overview

This article derives a condition for detecting multiplication overflow when an unsigned variable is multiplied by a non-zero constant. It concludes that overflow occurs if and only if the variable exceeds the relevant integer-division threshold, while noting that a direct comparison is likely more efficient and that the Go compiler does not perform this conversion.

## Source excerpt

Suppose that x is a variable of an unsigned type. In C/C++, it could be of type size_t for example. You have an expression like 6 * x and you want to know whether 6 * x overflows. That is, you want to know if 6 * x exceeds the range of values that can ... Continue reading Checking multiplication overflow