The Building Services Portal Fan Sizing Method
The building Services Portal fan sizer is the easy to use, simple concise method to accurately calculate fan duties. Dive right in and use the below embedded spreadsheet (desktop and tablet only), or scroll down for further options. Download the free version now which includes detailed instructions and general fan sizing guidance.

Please be patient as the spreadsheet below loads.
Tips…
White cells are to be filled in as required, with shaded cells displaying automatically calculated values. Further instructions and useful general fan sizing tips are contained within the downloadable free spreadsheet in the link below. Also see below for the basic and premium versions.
Fan sizing options
Free

£ Free
Features
- Excel format
- Download now or try using the embedded spreadsheet above
- For systems with up to 6 separate sections (6 calculation rows), ideal for smaller ventilation systems.
- Clear and easy to follow instructions included
- Building Services Portal general fan sizing tips included
- No sizing charts required. As a result, the Fan Sizer is quick and simple to use.
Basic

£ 10 (incl. VAT)
All features of the free version plus…
- For systems with up to 20 separate sections (20 calculation rows) and ideal for small to large domestic and commercial ventilation systems.
- Enter project information to organise your calculations for multiple systems and projects
- Note, this version does contain the Building Services Portal logo and basic version watermark.
Premium

£ 49 (incl. VAT)
All features of the basic version plus…
- For systems with up to 30 separate sections (30 calculation rows). As a result, the Premium Fan Sizer ideal for any sized domestic or commercial ventilation system.
- Features your company logo and watermark removed for professional presentation of your calculations.
- Option to change advanced variables- roughness, air temperature, density and viscosity.
- Option to display advance fluid dynamics calculations including dynamic viscosity, Reynolds number, Lamda and pressure velocity, all automatically calculated.
- Customer support- Our team of Chartered Engineers respond to all product related questions within 1 working day.
Design Pack

£ 98 (incl. VAT)
Premium Design Pack Includes…
- The Premium Building Services Portal fan sizer spreadsheet
- The Premium Building Services Portal Pump sizer spreadsheet
- The Premium Building Services Portal Water Efficiency Calculator
- Free delivery
- 90-Day, money back guarantee
Fan Sizing Options, Further Details...
Free Version
Easy to Use
Simply enter the variables for your chosen system and the fan duty calculator will do the rest. Fan duties can be calculated from entering the below information;
- Ductwork size for each system section
- Flow rates for each system section
- Quantities of each fitting type and length of flexible duct
- Design allowances
- Addition losses such as louvres/ grilles/ diffusers
There is no need for duct sizing charts, velocities and pressure losses are all calculated automatically! As a result, the Fan Sizer is extremely quick and simple to use.
The spreadsheet can be used to select appropriate duct sizes for each section of your system. Thus making the system ventilation system sizing a swift and easy process.
Instructions and general Fan sizing guidance included
The fan sizing spreadsheet includes detailed instructions for use and general fan sizing advice. Simply click on the relevant tab at the bottom of the page to display the different sheets containing the guidance.
Download the free version now to experience the ease of use that makes the Building Service Portal fan sizer the choice for your building services design needs.


Basic Version
Instructions and general Fan sizing guidance included
The basic version includes an expanded 20 calculation rows which makes it ideal for domestic and commercial ventilation systems.
Enter you project information to organise your calculations across different ventilation systems and projects.
Note, this version does display the Building Services Portal logo and basic version watermark. To display your company logo and watermark removed, up grade to the Premium version.
Basic Fan Sizer – £10 (incl. VAT)

Premium Version
Present your calculations professionally
The Premium version is ideal for professionally presenting your calculations. The premium version includes your company logo and no watermarks. Therefore, the Premium version is ideal for presenting calculations to clients. Your company logo will be in place of the Building Services Portal logo.
Include up to 30 rows of calculations per sheet so can be used from small domestic up to large commercial systems.
Includes the option to display advanced fluid dynamic calculations including dynamic viscosity, Reynolds number, Lamda and pressure velocity, all automatically calculated.
Option to change advanced variables, including roughness (to suit different materials), air temperature, density and viscosity.
The spreadsheet is suitable for many different pump applications including commercial, residential, industrial, domestic etc. Importantly, all calculations are to industry recognised methods.
The Premium version comes with the added benefit of customer support. Our team of Chartered Engineers will respond to any questions relate to the fan sizer within 1 working day.
Once more, we are confident that you will be happy with your purchase but offer a no quibble 90-day money back guarantee.
Premium Fan Sizer – £49 (incl. VAT)



Building Services Portal- Premium Design Pack
The Premium Design Pack Includes the following;
- The Building Services Portal Premium Fan Sizer
- The Building Services Portal Premium Pump Sizer
- The Building Services Portal Premium Water Efficiency Calculator
- Customer Support
- 90-Day Money Back Guarantee
Premium Design Pack – £98 (incl. VAT)
The Building Services Portal Fan Sizer is powered by Microsoft Excel.