---
title: "Memory pressure on a Mac · MacMelon"
description: "Memory pressure is how hard macOS is working to find memory for running apps. It, not memory used, says whether a Mac is short on memory. Sentinely reads it."
url: "https://macmelon.com/glossary/memory-pressure"
---

# Memory pressure

How hard macOS is working to make room in memory. The signal that a Mac is actually short on memory, not just using it.

A Mac using most of its memory is normal. macOS keeps recently used data in memory as cache because empty memory does nothing. Memory pressure is different: it tells you whether macOS is struggling to find room. The kernel tracks it as a level, and Activity Monitor shows it as a green, yellow, or red graph on its Memory tab.

When pressure rises, macOS compresses memory first, then writes some of it to disk as swap. That is when app switches start to lag. [Sentinely](https://macmelon.com/apps/sentinely) uses the kernel's pressure level, together with how often the Mac reads memory back from swap, to decide whether anything is wrong. See [Find out why your Mac is slow](https://macmelon.com/use-cases/find-out-why-your-mac-is-slow).

## Apps

[No more Force Quit in the middle of a build. ### Sentinely](https://macmelon.com/apps/sentinely)

## Related guides

[### How to find what's slowing down your Mac](https://macmelon.com/guides/how-to-find-what-is-slowing-down-your-mac)

## Related use cases

[### Find out why your Mac is slow](https://macmelon.com/use-cases/find-out-why-your-mac-is-slow)[### Get memory back from local AI models and Docker Desktop](https://macmelon.com/use-cases/get-memory-back-from-ollama-and-docker)

## Related terms

[Memory macOS has moved from RAM to the startup disk because RAM ran short. ### Swap](https://macmelon.com/glossary/swap-memory)[Memory macOS has squeezed in place to make room, before it writes anything to disk. ### Compressed memory](https://macmelon.com/glossary/compressed-memory)[The memory macOS charges to a process, including memory it has compressed. Sentinely's unit for estimates and receipts. ### Memory footprint](https://macmelon.com/glossary/memory-footprint)