What is the air change rate?

It tells how many times the room air is replaced per hour. Homes ~0.5 1/h.

How do I convert m³/h to L/s?

Divide by 3.6. E.g. 36 m³/h = 10 L/s.

Ventilation Calculator

Name: Ventilation Calculator
Author: Miikka

Calculate a room's ventilation need (m³/h and L/s) from volume and air change rate.

By Miikka · CalcBrew · Updated Jun 30, 2026

Area: 215 sq ft

Ceiling height: 8.2 ft

Air changes per hour: 2.00 1/h

58.9 cfm

Airflow need

Volume	65.40 cu yd
Airflow	58.9 cfm
Liters per second	58.9 cfm

ℹ️ For homes the guideline is ~0.5 1/h; higher for wet rooms and kitchens. 1 m³/h = 0.278 L/s.

The ventilation calculator works out how much airflow a room needs for adequate ventilation. Enter the area, ceiling height and air change rate, and you get the required airflow both in cubic metres per hour and litres per second.

How the calculator works and what it’s for▾

How the airflow is calculated

The calculator first works out the room volume by multiplying the area by the ceiling height. It then multiplies that volume by the air change rate, which tells you how many times per hour the room's entire air content is replaced.

The result is also converted to litres per second, the unit often used in ventilation design. The conversion is based on the relationship 1 m³/h = 0.278 L/s.

What you enter and what you get

You enter the room area in square metres, the ceiling height in metres and the desired air change rate in units of 1/h.

The result shows the volume, the required airflow in cubic metres per hour and the same value in litres per second.

Choosing the right air change rate

For homes a common guideline is around 0.5 1/h, meaning half the room's air is replaced each hour. Wet rooms and kitchens need a higher rate to remove moisture and odours.

Pick the rate to match how the space is used: a bedroom is fine with a modest value, while a damp room needs more effective ventilation.

What the calculator is for

The calculator helps you gauge the rough capacity needed from a ventilation unit or extractor fan, for example when planning ventilation during a renovation or for a cabin.

Exact ventilation sizing always requires whole-building design and compliance with regulations, so treat the result as an indicative estimate.

🔄 Reviewed June 2026

Frequently asked questions

Cite this calculator

APACalcBrew. (2026). Ventilation Calculator. https://calcbrew.com/ventilation-calculator

MLA“Ventilation Calculator.” CalcBrew, 2026, calcbrew.com/ventilation-calculator.

Link to https://calcbrew.com/ventilation-calculator. Results are estimates; cite the underlying formula or data source for academic work.

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