How We Test Cooker Hoods - Which?

We've tested dozens of cooker hoods from a range of big brands in our specialist test lab every year. But what do we actually do to them, and why are Which? tests some of the most rigorous around?

Unlike free-to-access websites that typically get all the cooker hoods they review free from manufacturers or their PR representatives, we buy all the appliances we test ourselves. That means you can have complete trust in our verdicts. Stainless Steel Under Cabinet Hood

How We Test Cooker Hoods - Which?

The Which? overall percentage score is calculated purely on the measurements and ratings supplied by our laboratory, meaning there's no room for unconscious bias when giving our ratings.

See the top-scoring models on our best cooker hoods page.

A quick guide to the recommendations you'll see on our reviews.

A cooker hood needs to score 70% in our tests to get our Best Buy recommendation.

Best Buy-rated cooker hoods eliminate odours in double-quick time and help to to keep your surfaces grease-free – all without making a racket.

They also excel at removing smells, grease and steam.

Cooker hood prices vary significantly, with some premium models costing more than £1,400.

Great Value cooker hoods are at least 20% cheaper than the average cooker hood we test, and score 65% or more - so you can be sure you'll be getting a decent product at a decent price.

Look out for Great Value models that also score highly enough to be Best Buys.

Cooker hoods that score 45% or less are ones to avoid and are highlighted as Don't Buys.

Don't Buy cooker hoods have massive struggles in important areas such as extracting airborne grease or clearing out a steamy kitchen, and aren't worth spending your money on.

The Which? overall score is a percentage. This score only takes into account the results of our tests and ignores price completely.

This means all the cooker hoods are tested on exactly the same scale, so you can compare any cooker hood at any price and see how it measures up against its rivals in key areas.

All the tests described below contribute to the overall test score, which we then turn into the percentage score.

However, some assessments are more important than others. For example, you've told us that a cooker hood's most important task is extracting grease, odours and steam, so we give this a high weighting when calculating the overall score.

To keep things simple, the most important scores are shown as star ratings out of five on each cooker hood's Test Results section as an easy-to-compare list of strengths and weaknesses. This means you can quickly work out if a cooker hood is right for you.

The score is broken down as follows:

Below are the key cooker hood testing categories and how we evaluate each one.

Please note that all our tests are undertaken in evacuation mode, where the steam and smells travel out of the kitchen via a duct. If you use a hood in recirculation mode, you might get different results.

Key question: How well does the cooker hood remove steam?

We test how well a cooker hood will remove steam from a kitchen by boiling four pans of water on the hob until humidity levels in our test chamber reach 90%. We then switch on the hood and record how quickly it reduces the humidity to 60%. 

The worst simply aren’t powerful enough to clear the steam and can take nearly twice as long as the best to do the job, leaving your kitchen uncomfortably humid for longer.

Key question: How well does the cooker hood remove grease?

We see how well each cooker hood can clear the kind of grease produced when you're frying, by dripping vegetable oil and water into a hot pan on a hob for 30 minutes. 

This creates a horrible, greasy atmosphere and is a tough test for any hood. We weigh the cooker hood filters before the test, and again afterwards, and record how much grease has been captured.

The best cooker hoods are excellent and will capture around 80% of the grease. But the worst struggle to remove much more than 50%, which means you'll be left with unpleasant, greasy kitchen surfaces.

Key question: How well does the cooker hood remove smells?

To test how well a hood removes smells, we use the pungent chemical methyl ethyl ketone, which smells like nail polish remover. 

This is dripped with water into a hot pan to make our test chamber very smelly. We then record (using a flame ionization detector) how smelly the chamber is at four points around the room before the cooker hood is turned on, and again after the cooker hood has been on for 30 minutes.

A powerful cooker hood, set up and installed correctly, should have no problem removing smells. But less powerful cooker hoods will leave you with lingering odours.

Grease, odour and steam extraction accounts for 60% of a cooker hood's score.

Key question: How easy is it to use and clean?

First, we assess how easy each hood is to install and we rate the clarity of the supplied instructions.

We then see how easy the cooker hood is to use, taking into account variation in people's height, hand size and strength. A cooker hood with stiff or fiddly controls won't enhance your cooking experience, and we mark down any hoods that are awkward to use. 

We also measure the brightness of the light and see how evenly it will light up your pots and pans.

If your cooker hood has hard-to-reach nooks and crannies or obvious places for cooking grime to collect, it will be a pain to clean. We make the cooker hoods grubby, then assess just how easy each one is to clean, and whether it's awkward to get around any controls or edges. We also use an abrasive detergent to find out which ones can tolerate this without being damaged.

Ease of use and cleaning accounts for 20% of a cooker hood's score.

Key question: How noisy is it?

A cooker hood is basically a big fan, so it's bound to make a bit of noise. But some are a lot louder than others.

We record how noisy each cooker hood is in our noise chamber and listen out for any strange sounds, rattles or vibrations. The cooker hoods we’ve tested range from a quiet 50 decibels (about equivalent to the hum of a refrigerator) to around 67 decibels, which is more like the noise you get from a vacuum cleaner or hair dryer.

If you have an open-plan kitchen where you'll be eating after you've cooked, or if you like to listen to the radio and chat while cooking, then opt for one of the hoods that scores four stars or more in our noise tests.

Noise accounts for 15% of a cooker hood's score.

Key question: What's the build quality like?

Cooker hoods need to be attached to a wall, hung from the ceiling or built into a kitchen cabinet, so they must be well made.

In our tests, we check for build quality, sharp edges and finishing. The best cooker hoods feel solid on the outside and when changing the grease filter. A poor cooker hood has a flimsy feel.

Build quality accounts for 5% of a cooker hood's score.

In our independent, scientific cooker hood tests, we've found models less effective than an open window and a waving dishcloth, models that make quick work of any lingering odours or fumes, and everything in between.

Only a small proportion of cooker hoods manage the 'holy grail' of quiet, effective extraction and are good enough to become Which? Best Buy cooker hoods. Price is not a reliable indicator of quality – we've tested some high-end models that barely clear the air, despite costing hundreds of pounds.

We can help you to steer clear of ineffective cooker hoods that are noisy and leave your kitchen filled with cooking smells or smoke.

Go to our cooker hood reviews to discover the best and worst models of each type.

How We Test Cooker Hoods - Which?

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