---
title: "What is the visual monitoring diff threshold? — Lemwatch…"
description: "The diff threshold sets how much pixel change must accumulate before Lemwatch alerts — default 2% is right for most product pages."
canonical: "https://lemwatch.com/help/visual-monitoring-diff-threshold"
source: "https://lemwatch.com"
---

# What is the visual monitoring diff threshold?

> The diff threshold sets how much pixel change must accumulate before Lemwatch alerts — default 2% is right for most product pages.

## Quick answer

 The threshold is the % of pixels that must change (after ignore-zone masking) before an alert fires. Default is **2%**, which catches copy edits and layout shifts while ignoring anti-alias jitter.

## Recommended thresholds

- Pricing / legal pages : 0.5% (very tight)

- Product / hero : 2% (default)

- Blog / editorial : 5% (loose)

- Homepage with carousels : use ignore zones + 2%

## Where to find it in Lemwatch

 **Site → Visual Monitoring → <page> → Sensitivity**.

## FAQ

### Why not just alert on any pixel change?

 Browsers subtly re-render fonts and anti-aliasing between runs. 0% would page you constantly.

## Related

- CSS selectors

- Ignore zones


## Related

- [Help centre](https://lemwatch.com/help)
- [How do CSS selectors work in visual monitoring?](https://lemwatch.com/help/visual-monitoring-selectors)
- [How do I stop visual monitoring flagging ads or rotating banners?](https://lemwatch.com/help/visual-monitoring-ignore-zones)
- [How do I monitor a JSON API endpoint?](https://lemwatch.com/help/monitor-json-api-endpoint)
- [How does API endpoint degradation alerting work?](https://lemwatch.com/help/api-endpoint-degradation)
- [Lemwatch pricing](https://lemwatch.com/pricing)
- [Visual diff thresholds explained](https://lemwatch.com/help/visual-diff-thresholds)