One of the most common mistakes Australians make when purchasing a rangehood is choosing it primarily for looks — and ending up with a beautiful appliance that doesn't actually do its job properly. Correct sizing is the single most important factor in rangehood performance, and getting it right isn't complicated once you understand the basic principles. This guide walks you through everything you need to know to match a rangehood to your cooktop and your kitchen.

Width: The Most Important Dimension

The fundamental rule for rangehood sizing is that your rangehood should be at least as wide as your cooktop, and ideally wider. The logic is straightforward: if the capture area of the rangehood is narrower than your cooktop, steam and smoke from the burners or zones at the edges will escape into the kitchen rather than being drawn into the hood.

Most Australian cooktops come in standard widths: 60cm, 75cm, 90cm, and occasionally 120cm. If you have a 60cm cooktop, a 60cm rangehood is the minimum — a 90cm rangehood above a 60cm cooktop gives you comfortable capture margin and is worth considering if your cooktop sits on an island bench or if you do a lot of high-heat cooking. For 90cm cooktops, a 90cm rangehood is the standard pairing, with some high-performance cooks opting for a 120cm hood. For 75cm cooktops, a 90cm rangehood is the usual recommendation.

The extra width matters most if you cook at high heat, do a lot of wok or frying work, or if your kitchen has ceiling fans or air conditioning that disrupts the natural thermal plume rising from the cooktop.

Height Clearance: Complying with Australian Requirements

Australian building standards specify minimum clearance distances between your cooktop and the underside of the rangehood's filter:

• Gas cooktops: minimum 650mm clearance
• Electric (ceramic) cooktops: minimum 600mm clearance
• Induction cooktops: minimum 750mm clearance (the cooler surface creates less of an upward thermal current, so the hood needs to be positioned lower to capture effectively — but induction also generates significant steam, and condensation on a cold rangehood surface is a real consideration)

These are minimums. In most kitchens with standard ceiling heights, rangehoods end up installed somewhere between 650mm and 800mm above the cooktop surface, which is a practical working zone for most cooking scenarios. Installing a rangehood too high above the cooktop significantly reduces its effectiveness regardless of how powerful it is.

Extraction Power: Understanding Airflow Ratings

Rangehood extraction power is rated in cubic metres per hour (m³/h), measuring how much air the fan can move. Getting this specification right is just as important as getting the physical dimensions right.

For Australian kitchens, a rangehood with 600–700 m³/h is considered adequate for moderate cooking. 800–1,000 m³/h is the range considered powerful and appropriate for heavier cooking styles or larger kitchens. Commercial-style rangehoods used above 5-burner gas cooktops or professional wok burners can exceed 1,200 m³/h.

A useful rule of thumb: for every 10 cubic metres of kitchen volume, you want approximately 10 times that in extraction capacity, on a 10 air-changes-per-hour basis. A typical open-plan kitchen of 30–40 cubic metres benefits from a rangehood rated at 700–900 m³/h. Open-plan living areas that flow directly from the kitchen will benefit from stepping up in extraction power since there's a larger volume of air to manage.

For ducted rangehoods, duct diameter matters too. A narrow or kinked duct will restrict airflow and cause a powerful motor to underperform. Most ducted installations work best with 150mm round ducting with minimal bends — every 90-degree bend in the duct run effectively reduces the system's practical airflow.

Depth Matters Too

Rangehood depth — the front-to-back dimension — determines how much of the cooktop's surface falls within the capture zone. A hood that's too shallow will struggle to capture smoke from the front burners of a deep cooktop. Most quality rangehoods have a depth of around 500mm, which suits the majority of standard cooktops. If you have a particularly deep cooktop (some 5-burner models are 70–80cm deep front to back), checking the rangehood's canopy depth is worthwhile.

Island Cooktops

If your cooktop is on a kitchen island, sizing requirements are more generous than for wall-mounted situations. Without a wall behind the cooktop to act as a barrier, thermal plumes are affected by air currents from all directions. For island installations, a rangehood 10–20cm wider than the cooktop is strongly recommended, and extraction power should be stepped up compared to equivalent wall-mounted setups.

Getting your rangehood sizing right from the start costs nothing extra and ensures the appliance you invest in actually performs the way it should for years to come.