On this page you can estimate the size of the ducts for the correct functioning of the ventilation system. The tool helps to calculate the cross-sectional area of the ducts according to the values of air exchange and air velocity of the air flow. Please note that the recommended velocity for residential areas is 3-5 m/s (but no more than 10 m/s). The required parameters for the calculation can be seen on the notation below. To get the result, click the "**Calculate**" button.

## How to calculate the cross-sectional air duct area?

Formula cross-sectional air duct area: S (m^{2}) = L / (3600 × V)

- L – indoor air exchange, m
^{3}/h; - V – air velocity, m/s.

Formula for calculating rectangular duct side (at A=B): A (mm) = 1000 × √S

Formula for calculating round duct diameter: D (mm) = 1000 × 2 × √(S / 3.14)

- L – cross-sectional area, m
^{2}.

## Recommended values of air velocity in the ventilation system, m/s

Apartment | Office | Manufacture | |

Supply grilles | 2.0-2.5 | 2.0-2.5 | 2.5-6.0 |

Main air ducts | 3.5-5.0 | 3.5-6.0 | 6.0-11.0 |

Branches | 3.0-5.0 | 3.0-6.5 | 4.0-9.0 |

Air filters | 1.2-1.5 | 1.5-1.8 | 1.5-1.8 |

Heat exchangers | 2.2-2.5 | 2.5-3.0 | 2.5-3.0 |