# How much disk space screen memory takes.

At Earlyn's default 2,560-pixel capture, a busy hour of screen memory takes about 9 MB, which is around 160 stored moments at roughly 52 KB of picture and 4.5 KB of text each, and a still screen stores nothing.

## Per hour, per day, per history window

Assumes every hour of the day is busy; real days are usually lighter. Meeting audio, when kept, adds about 14 MB an hour. Settings → Storage shows your own rate.

| Period | Pictures | Text | Total |
| --- | --- | --- | --- |
| One busy hour | 8.3 MB | 0.7 MB | about 9 MB |
| An 8-hour workday | 66 MB | 6 MB | about 72 MB |
| A month of workdays (22) | 1.5 GB | 0.1 GB | about 1.6 GB |
| Pro's 90-day window (≈64 workdays) | 4.2 GB | 0.4 GB | about 4.6 GB |

## Why so little

- Earlyn keeps a frame only when the text on screen changed; ScreenCaptureKit sends nothing while the screen is still.
- Frames go into HEVC video made by the Mac's hardware encoder, which stores the small differences between moments very compactly.
- Terminals change every second and produce the most moments, about 1.4 KB of text each.

## Resolution: what 2,560 pixels buys

A scripted 10-minute session, 27 stored moments, the same screens at each width. Encoding cost 0.6–2.7 ms per frame at every width.

| Capture width | Picture per moment | Text legibility |
| --- | --- | --- |
| 1,440 px | 30 KB | Readable but soft for 11–13 px text |
| 2,560 px (default) | 52 KB | Near crisp |
| Native (3,420 px on a 2× display) | 87 KB | Crisp |

When an app exposes no text, Earlyn reads the picture with on-device text recognition. On a 2× display the 1,440-pixel stream was useless for that (0–16% of words recovered); at 2,560 pixels recovery came within 4 to 9 points of a native-resolution screenshot:

Recall against the text the app exposes through Accessibility. Apple's slower “accurate” recognition added only a few points at three to four times the cost.

| App | Words recovered at 2,560 px | At native resolution |
| --- | --- | --- |
| Safari | 85% | 93% |
| Xcode | 75% | 79% |
| Zed | 88% | 92% |
| Slack | 50% | 59% |

## Cost of encryption

Scrubbing the timeline over encrypted segments took 5.7 ms per thumbnail and 6.6 ms per full frame, the same as unencrypted, because a segment is decrypted once into memory and then read from there.

## Questions

### Which Mac were these measured on?

Earlyn's development Mac, an Apple Silicon MacBook with a 2× Retina display, in September 2026, with the app's own debug benchmarks.

### Can I make it smaller?

Yes: shorten the history window, set shorter windows for busy apps, or lower the capture quality in Settings → Storage.

---
Canonical: https://www.earlyn.app/research/screen-memory-storage · Updated 2026-10-02