Standard Enclosed Kitchen (Electric/Induction)
Standard Enclosed Kitchen (Gas Hob)
Open Plan / Kitchen Diner
Island Cooker (Any Type)
Total Kitchen Volume:0 m³
Minimum Extraction Rate (10 changes/hr):0 m³/h
Optimal Extraction Rate (12 changes/hr):0 m³/h
Note: For Island or Open Plan layouts, higher extraction rates are critical to prevent smells from spreading to living areas. We recommend aiming for the "Optimal" rate or higher.
Understanding Cooker Hood Extraction Rates
Choosing the right cooker hood is about more than just aesthetics; it is a matter of physics and air quality. The extraction rate, typically measured in cubic meters per hour (m³/h), determines how effectively the device can filter the air in your kitchen. If the rate is too low, grease, steam, and cooking odors will linger and spread throughout your home. If it is too high, you may waste energy and generate unnecessary noise.
How is Extraction Rate Calculated?
The industry standard calculation for determining the necessary airflow is based on the volume of your kitchen and the number of times the air needs to be "changed" or filtered per hour. Most manufacturers and ventilation experts recommend between 10 to 12 air changes per hour.
Kitchen Volume: Larger rooms hold more air, requiring a more powerful motor to cycle that air effectively.
Hob Type: Gas hobs generate significant heat and combustion byproducts compared to electric or induction hobs. If you cook with gas, aim for the upper end of the extraction scale (12+ changes per hour).
Kitchen Layout:
Enclosed Kitchens: Air is contained, making it easier to filter. 10 changes per hour is usually sufficient.
Open Plan / Kitchen Diners: Smells can easily drift into living spaces. Higher extraction rates are required to trap fumes immediately.
Islands: Island hoods are susceptible to cross-drafts from all directions, unlike wall-mounted hoods which are aided by the wall. They require higher extraction power to capture the rising plume of steam effectively.
Ducting: The length and shape of your ducting matter. Every 90-degree bend in your ducting reduces efficiency significantly (often equivalent to adding 1 meter of length). Always oversize your hood slightly to compensate for duct resistance.
Real-World Example Calculation
Consider a standard kitchen that measures 4 meters long, 3 meters wide, and has a ceiling height of 2.5 meters.
Calculate Volume: 4m × 3m × 2.5m = 30 m³.
Minimum Rate (10 changes): 30 m³ × 10 = 300 m³/h.
Optimal Rate (12 changes): 30 m³ × 12 = 360 m³/h.
If this kitchen were open-plan or used a large gas range, we would recommend looking for a model with at least 400-450 m³/h capacity to ensure peak performance.
CFM vs. m³/h
While most European specifications use cubic meters per hour (m³/h), some manufacturers use Cubic Feet per Minute (CFM). To convert m³/h to CFM, you divide by approximately 1.7. Conversely, 1 CFM is roughly 1.7 m³/h.
function calculateExtraction() {
// 1. Get Input Values
var lengthInput = document.getElementById('k_length');
var widthInput = document.getElementById('k_width');
var heightInput = document.getElementById('k_height');
var typeSelect = document.getElementById('k_type');
var l = parseFloat(lengthInput.value);
var w = parseFloat(widthInput.value);
var h = parseFloat(heightInput.value);
var type = typeSelect.value;
// 2. Validate Inputs
if (isNaN(l) || isNaN(w) || isNaN(h) || l <= 0 || w <= 0 || h <= 0) {
alert("Please enter valid positive numbers for all kitchen dimensions.");
return;
}
// 3. Calculate Volume
var volume = l * w * h;
// 4. Determine Multipliers based on type
// Standard baseline is 10 to 12.
// We will display a range.
// Adjustments:
// Gas: +10% recommended load
// Open Plan: +20% recommended load
// Island: +30% recommended load due to lack of containment walls
var minMultiplier = 10;
var optMultiplier = 12;
// Apply logic for specific types to adjust the "Optimal" suggestion
if (type === 'standard_gas') {
// Gas creates more heat/moisture, push optimal higher
optMultiplier = 13;
} else if (type === 'open') {
// Open plan needs to prevent smell spread
minMultiplier = 11;
optMultiplier = 14;
} else if (type === 'island') {
// Islands are least efficient at capture, need high power
minMultiplier = 12;
optMultiplier = 15;
}
// 5. Calculate Rates
var minRate = Math.ceil(volume * minMultiplier);
var optRate = Math.ceil(volume * optMultiplier);
// Convert to CFM for reference (1 m3/h = 0.588578 CFM)
var minCFM = Math.ceil(minRate * 0.5886);
var optCFM = Math.ceil(optRate * 0.5886);
// 6. Display Results
document.getElementById('res_volume').innerText = volume.toFixed(2) + " m³";
document.getElementById('res_min').innerHTML = minRate + " m³/h (" + minCFM + " CFM)";
document.getElementById('res_opt').innerHTML = optRate + " m³/h (" + optCFM + " CFM)";
// Show warning for open/island layouts
var warningBox = document.getElementById('island_warning');
if (type === 'open' || type === 'island') {
warningBox.style.display = 'block';
} else {
warningBox.style.display = 'none';
}
// Reveal result container
document.getElementById('results').style.display = 'block';
}