How to Size Your Cooker Hood to Your Kitchen

To work out the capacity you need, calculate the volume of your kitchen (length × width × height) and multiply it by 10–12: that is how many air changes per hour the hood should achieve. For a 4 × 3 m kitchen with a 2.5 m ceiling, that comes to 30 m³, so a hood of 300–360 m³/h at maximum normal speed. As for hood height, manufacturers’ manuals usually call for a clearance of 65–75 cm above a gas hob and 50–65 cm above an electric or induction hob; the exact figure is the one in your model’s manual. Below you will find the step-by-step calculation, a table by floor area and answers on duct diameter and energy consumption.

Choosing the right cooker hood for your kitchen is not just about design and extra features; above all, it comes down to its extraction capacity. An undersized hood will not remove steam and smells effectively, while an oversized one may use more energy than necessary.

How to Calculate Hood Capacity, Step by Step

1. Calculate the Volume of Your Kitchen

To establish the optimum hood capacity, first find out the volume of the room:

Kitchen volume = length × width × height

For example, for a kitchen 4 m long, 3 m wide and 2.5 m high: 4 × 3 × 2.5 = 30 m³.

2. Set the Air Change Rate

An efficient hood should be able to change the air in the kitchen roughly 10–12 times an hour. The capacity you need is calculated as follows:

Hood capacity (m³/h) = kitchen volume × air change rate

For the example above, at 10 changes per hour: 30 × 10 = 300 m³/h. If you want higher performance, choose a hood between 300 and 360 m³/h.

3. Consider the Way You Cook

If you cook often and use techniques that produce a lot of steam or smoke (frying, grilling, heavy cooking on several burners), choose a hood with capacity to spare, towards the top of the range or above it. That way the hood copes on its middle settings and does not have to run flat out all the time, which also means less noise.

4. Factor In the Length and Shape of the Extraction Duct

A hood’s performance also depends on the route of the duct. The longer the route and the more bends it has, the greater the losses. In that case, choose a model with a higher capacity.

5. Compare the Right Airflow Figure

The energy label of every hood lists three airflow figures: at minimum speed, at maximum normal speed and in intensive (boost) mode. For sizing, use the airflow at maximum normal speed, not the boost figure in the product title. For instance, the Haier HADG6CBS4BWIFI hood delivers 624 m³/h at maximum normal speed and 974 m³/h on boost.

Hood Capacity by Kitchen Floor Area

The table below is calculated for a ceiling height of 2.5 m. If your ceiling is higher, redo the calculation with the actual height.

Kitchen floor area	Volume (at 2.5 m)	Minimum airflow (10 changes/h)	Recommended airflow (12 changes/h)
6 m²	15 m³	150 m³/h	180 m³/h
8 m²	20 m³	200 m³/h	240 m³/h
10 m²	25 m³	250 m³/h	300 m³/h
12 m²	30 m³	300 m³/h	360 m³/h
15 m²	37.5 m³	375 m³/h	450 m³/h
20 m²	50 m³	500 m³/h	600 m³/h
25 m² (open plan)	62.5 m³	625 m³/h	750 m³/h
30 m² (open plan)	75 m³	750 m³/h	900 m³/h

For a kitchen that opens onto the living room, calculate the volume of the whole shared space, not just the cooking area. You will find layout ideas in our article on open-plan kitchen designs.

How High to Fit the Hood Above the Hob

The distance is measured from the surface where the pans sit on the hob to the lowest part of the hood. The figures vary from one manufacturer to another. In the manuals we consulted, the minimum distance is between 50 and 65 cm for electric and induction hobs and between 65 and 75 cm for gas hobs. The safe rule: read both the hood manual and the hob manual, and follow whichever distance is greater. A hood fitted too low gets in the way while you cook and, over a gas hob, can be dangerous; one fitted too high extracts less effectively.

Hood Dimensions: Width and Height

As a rule, you choose a hood at least as wide as the hob: a 60 cm hood for a 60 cm hob, a 90 cm hood for a wider hob. Chimney hoods usually have a telescopic flue with adjustable height; check the adjustment range on the technical data sheet and compare it with your ceiling height. For example, the Falmec Polar Black island hood adjusts between 84 and 124 cm. If you are choosing your hob now as well, you will find it in our built-in hobs category.

Hood Extraction Duct Diameter

The most common ducting diameters are 150 mm and 120/125 mm. Use the diameter stated in the hood’s manual: a narrower duct or a reducer fitted along the route increases the resistance to airflow, so the hood extracts less effectively and makes more noise. Wherever possible, choose rigid ducting, a short route and as few bends as you can. Where the duct exits to the outside, a vent grille or cap is fitted, ideally with a flap that closes when the hood is switched off.

How Much Energy Does a Cooker Hood Use?

Annual consumption is shown on the energy label, calculated on the basis of standard use as set out in the European regulation. For a few models from our store, at a price of 1.30 lei/kWh:

• Haier HADG6CBS4BWIFI (class A++): 26.2 kWh/year, roughly 34 lei a year;
• Haier HATS6CBS4BWIFI (class A+): 30.1 kWh/year, roughly 39 lei a year;
• Candy CBT625/2B/1 (class B): 27.1 kWh/year, roughly 35 lei a year.

Actual consumption depends on how long and on which setting you use the hood, but the order of magnitude shows that a well-chosen hood will not make a noticeable dent in your bill.

Noise Level

Besides capacity, check the noise level, expressed in decibels (dB), on the same energy label, at minimum and at maximum normal speed. A hood with a higher airflow used on a low setting can be quieter than a small one running at full power. We cover this in detail in our guide to the quietest cooker hood.

You will find every model, from built-in hoods to chimney and island hoods, in our cooker hoods category.

Frequently Asked Questions

How high should a cooker hood be fitted?

In manufacturers’ manuals, the minimum distance between the hob and the bottom of the hood is usually 50–65 cm for electric and induction hobs and 65–75 cm for gas hobs. Always follow the greater of the two figures given in the hood manual and the hob manual.

What diameter is a cooker hood extraction duct?

Most often 150 mm or 120/125 mm. Use the diameter given in the hood’s manual; a narrower duct reduces extraction and increases noise.

How much energy does a cooker hood use?

According to their energy labels, the three models above use between roughly 26 and 30 kWh a year, which works out at around 34–39 lei a year at 1.30 lei/kWh.

What capacity does a hood need for a 10 m² kitchen?

With a 2.5 m ceiling, the kitchen measures 25 m³, so you need at least 250 m³/h, ideally around 300 m³/h at maximum normal speed.

What size should the hood be?

The width of the hood is usually chosen to be at least equal to that of the hob (60 or 90 cm), while the chimney height of a chimney hood is adjusted to suit the ceiling, within the limits given on the technical data sheet.

Sizing your cooker hood correctly for the size of your kitchen is essential for clean air and optimum performance. By taking into account the volume of the kitchen, the air change rate, the way you cook, the mounting height and the extraction duct, you will make an informed and efficient choice.