Extraction Rate Calculator

To help you determine the appropriate extraction rate for your bathroom, kitchen, utility room, etc, we have created a user-friendly and completely free Extraction Rate Calculator.

By using this tool, you can ensure that you pick the right size extractor fan for your application.

Simply enter the measurements of your room and click calculate to find out the correct cubic metres per hour or litres per second figure you need.

Extractor Fan Extraction Rate Calculator

What are the Regulations on Extraction Rate?

The Building Regulations Document F includes regulations for how much ventilation your bathroom requires.

It is an extremely long document but the important points are as follows:

  • For best results, aim for 15 litres per second or 54 m3 per hour of ventilation in your bathroom.
  • To keep a UK bathroom fresh and healthy, it needs proper ventilation. You can do this by either having a window or an extractor fan.
  • If you have a bath and a shower, you’ll need an extractor fan. This is because new builds are airtight, so natural ventilation is usually lower.
  • If your bathroom only has a toilet, a window will do.

Popular Extractor Fan Extraction Rates

To give you an idea of different extraction rates, we have put together a table below of the most popular extractor fans, together with their extraction rates, to help you decide which extractor fan you need.

NameExtraction Rate in m3/hExtraction Rate in l/s
Manrose MF100T24568
Envirovent SIL100T9627
Xpelair C4TS7621
Manrose QF100T7621
Vents Silenta7822
Airope Silenta 1007822
Vent-Axia VASF100T7621
Blauberg Calm 1009727
Blauberg 100 Quiet Style TH9727
Kair Smart18050

Frequently Asked Questions (FAQs)

Can I use this extraction rate calculator for my kitchen?

Yes, you can use this calculator for your kitchen. Kitchens typically require a larger, more powerful extractor fan, due to all the cooking and humidity caused by an oven or hob. Owing to this, a more optimal solution may be a cooker hood.

If you do still want to use this calculator, use the output or calculation as a minimum requirement for your kitchen.

I have used the calculator, now what?

Now that you have run the calculator and worked out what extraction rate you need from an extractor fan, you simply look for a decent model that has this extraction rate.

You can take a look at the earlier table for some inspiration and ideas.

How do you calculate the extraction rate?

Aside from using our extraction rate calculator, you can use the following formula:

Extraction rate (m3/hr) = room volume (m3) x recommended air changes per hour.

For example, if your bathroom is 3 meters long, 2 meters wide, and 2.5 meters high, the volume would be 15 cubic meters.

If you want to achieve 8 air changes per hour, the extraction rate would be 120 m3/hr (15 x 8).

This means the fan needs to be able to extract 120 cubic meters of air per hour to effectively ventilate the bathroom.

What is the minimum extraction rate for a bathroom?

The minimum extraction rate for a bathroom in the UK is 15 litres per second (l/s) or 54 cubic meters per hour (m³/h).

This is the minimum requirement set by the Building Regulations Part F and is based on the size of the bathroom.

For bathrooms that are smaller than 6 square meters, the minimum extraction rate is 15 l/s.

For larger bathrooms, an additional 3 L/s is required for every square meter over 6 square meters.

It is important to have proper ventilation and extraction in bathrooms to prevent the buildup of moisture, which can lead to mould and other problems.

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