Track mould risk. Understand your air. Protect your space

The Mould Risk Calculator is a free tool that helps you spot when your indoor environment could be at risk of mould before it becomes a problem.

It analyses temperature and humidity data over time using established scientific models. Whether you're using a Smart Air CO₂ Monitor, a QP device, or uploading your own data, the calculator shows how changing indoor conditions can lead to mould growth.

Why we built this

Mould affects health, damages homes and thrives under the radar. Yet many companies now charge a premium for tools like this, bundling them into expensive devices or apps, often without explaining the limits of what their models can really show.

We’ve taken a different approach. This calculator is:

• Free and open source
• Not limited to our own monitors
• Built from peer-reviewed research
• Designed to be transparent about what it can and can’t do

Before you dive in, it’s worth being clear: no mould risk calculator can give a perfect answer. The science behind mould growth is complex, and while this tool is based on a peer-reviewed model, it comes with real limitations, just like every other tool out there. What sets this one apart is that it’s free, open-source, and upfront about what it can and can’t do. We don’t lock the results behind a paywall or tie it to expensive hardware. If you're just looking to get a rough sense of risk based on your temperature and humidity data, this will do the job - no subscription needed!

But if you’re dealing with a serious mould problem, skip the calculators and talk to a qualified professional who can assess your home properly.

Understand the caveats

We’ve kept this tool open so you can explore the data yourself, but it’s important to understand the assumptions and limitations behind the results (see disclaimer below).

Start Calculator Disclaimer