## What is the formula for calculating duct size?

Duct CFM Calculation Formula

- Room CFM = (Room load/Whole house load) ✕ Equipment CFM.
- 24,000 BTUs ÷ 12,000 BTUs in 1 ton = 2 tons ✕ 400 CFM per ton = 800 CFM.
- Room A = (2,000 BTUs ÷ 24,000 BTUs) ✕ 800 CFM.
- Room A = 66.67 CFM.

### How do you calculate duct air flow?

Calculate the duct air flow, or “q,” using the formula: q = v x A. For example, if v is 15 m/s and the A is 8 square meters, q is 120 cubic meters per second or 120 m^3/s.

**What size duct do I need for 2000 cfm?**

Rectangular equivalent diameter for air flows between 100 – 50000 cfm.

Air flow – q – (Cubic Feet per Minute, cfm) (m3/s) | Rectangular Duct Sizes (inches) (mm) x (mm) |
---|---|

1700 (0.77) | 10 x 22 14 x 15 |

1900 (0.86) | 12 x 19 14 x 16 |

2000 (0.9) | 10 x 25 12 x 20 15 x 16 |

2500 (1.13) | 14 x 20 15 x 18 |

**How do you calculate flexible duct?**

Measure the length and width of the room where the flex duct will be supplying the air. Multiply the length and width together to get the square footage of the room. For example, a 10-by-10 room will be 100 square feet.

## What size duct do I need for a 12×12 room?

A 12×12 foot room will need a 4×8 inch supply duct to get an adequate CFM rate, which is about 144 CFM.

### How many CFM do I need for 1000 square feet?

Heat and energy recovery ventilators

Total area of home (square feet) | Continuous ventilation rate |
---|---|

1,000 square feet | 50 CFM |

2,000 square feet | 100 CFM |

3,000 square feet | 150 CFM |

**How do you calculate CFM for duct size?**

Cubic Feet per Minute (CFM) Cubic feet per minute is calculated by multiplying the size of the HVAC unit (in tons) by 400. Divide the answer by your home’s square footage to find out total CFM. A duct sizing calculator uses CFM and other factors to determine what you need.

**What size duct do I need for 1600 CFM?**

24×12

12-Inch Rectangular Ducts Size Chart (150-3,050 CFM)

12″ Duct | 12″ CFM |
---|---|

20×12 | 1,250 CFM |

22×12 | 1,400 CFM |

24×12 | 1,600 CFM |

26×12 | 1,750 CFM |

## How many CFM are in a ton?

1 ton of cooling is equal to 400 cubic feet of air per minute. 2 ton of cooling is 800 cfm and so on. So a 4 ton unit will have 1600 cubic feet of air passing through the system every minute.

### How many CFM do I need per room?

One cfm is needed per square foot (1 cfm/sq ft) of floor area. This is the average air quantity required for a room or an entire building. This number is based upon an averaged heat load calculation for comfort cooling. There is an assumption of an 8-ft ceiling, no unusual window areas, and average insulation.

**How many CFM do I need for a 10×10 room?**

135 CFM is needed per square foot of space. So, a 100 square foot room would need 13.5 CFM. A 1,000 square foot room would need 135 CFM.