When you stand in your kitchen planning a renovation or a simple upgrade, it is easy to get caught up in the aesthetics. We all want that sleek glass finish or that robust stainless steel look that anchors the room. But there is a technical reality that sits behind the design, and it starts with a simple question. Does this thing actually fit? And more importantly, will it work once it is installed? This is where understanding the correct chimney size becomes the most critical part of your buying decision.
This involves more than just checking if the appliance physically fits between two wall cabinets. That is the easy part. The real challenge, and the reason so many kitchens still smell of curry leaves and burnt oil despite having a hood, is that the chimney size was never calculated based on the physics of cooking. It was likely picked because it looked good or was on sale.
At Kaff, we see this often. A beautiful kitchen with a high-end hob paired with a ventilation unit that is simply too small or too weak to handle the volume of smoke being generated.
To get this right, you have to look at size in three dimensions plus a fourth hidden dimension which is power. We are going to walk through exactly how to measure your space, what numbers actually matter, and why the standard advice you might hear from a local carpenter could be wrong.
Why Chimney Size Is More Than Just Width
Most people assume that if they have a 60 cm stove, they just grab a 60 cm chimney and they are done. While that is a starting point, it is a massive oversimplification. Smoke rises in an expanding V-shape rather than a perfectly straight column. As heat rises from your pan, it spreads outwards, a phenomenon known as the thermal plume. If you are boiling water, that plume is relatively contained. If you are searing a steak or frying puris, that plume is chaotic, hot, and spreads rapidly.
If your chimney size matches your hob exactly, you rely entirely on the motor to be powerful enough to drag that expanding smoke inwards before it escapes into the room. This is why you will often hear experts, including our own engineers, suggest that if you have the space, you should go wider. A wider capture area means the physical canopy catches the rising smoke before the motor even has to do its work. It is a passive way to improve efficiency without adding noise or electricity costs.
But let’s break this down into the specific measurements you need to take before you even look at a catalogue.
Measuring the Width
The golden rule of ventilation is that your hood must be at least as wide as your cooking surface. If you have a four-burner gas stove that is 60 cm wide, a 60 cm chimney is the absolute minimum requirement. If you install a 90 cm hob, a 60 cm chimney will be virtually useless. The smoke from the outer burners will simply bypass the hood and drift up to your ceiling, leaving a greasy film on your cabinets over time.
For most Indian kitchens, you are looking at two standard width categories which are 60 cm and 90 cm.
The 60 cm Standard
This is the most common size for compact city apartments and kitchens with standard two or three-burner stoves. If your cooking counter is tight and your hob is standard-sized, this chimney size aligns perfectly with your setup. It covers the basic heating zones and will clear the air effectively provided it has decent suction. It is the default choice for many, but it leaves little room for error. You must ensure your pots are centered on the burners to maximize capture.
The 90 cm Upgrade
If you have a larger hob, say a three, four, or five-burner unit with a wider spacing, you need a 90 cm model. But here is a tip that is often overlooked. Even if you have a 60 cm stove, installing a 90 cm chimney is a fantastic upgrade if your cabinetry allows for it. That extra 15 cm of overhang on each side acts like a safety net for smoke. When a sudden burst of steam rises from a pressure cooker, or when you are tossing vegetables in a wok, that wider canopy catches the drift that a narrower unit might miss.
When measuring for width, measure the gap between your wall units in addition to the hob itself. You need a few millimetres of clearance on each side for installation. If you are planning a new kitchen, tell your designer you want the option for a wider hood. It is one of the best functional decisions you can make.
Depth and Front-Burner Coverage
Width gets all the attention, but depth is where many designs fail. In a typical Indian cooking session, you often use the front burners for the heavy lifting like making rotis, stir-frying vegetables, or boiling milk. These are the burners that generate the most smoke and steam, yet they are the furthest away from the wall.
If your chimney size regarding depth is too shallow, the hood might not extend far enough to cover these front burners. You end up with a situation where the back burners are well-ventilated while the steam from your tea pot on the front burner rises straight up past the front of the hood and into the room.
Standard depths usually range between 450 mm and 550 mm. When you are looking at specifications, check this number against your stove’s position. Ideally, the canopy should cover at least half of the front burners. If you have a particularly deep counter or your hob is installed further forward, you need to be very careful with this measurement.
There is a trade-off here. Avoid units that are so deep they become a head-banger. We have designed our angled and inclined models specifically to solve this. They offer excellent coverage without protruding aggressively into your standing space, giving you the best of both worlds with safety for your head and capture for your smoke.
Depth and Front-Burner Coverage
This dimension relates to installation rather than the product itself. However, it dictates which chimney size you can buy, specifically regarding the vertical stack or the duct cover.
There is a sweet spot for installation height.
• Too Low: It becomes a fire hazard. If the filters are too close to a naked flame, accumulated grease can catch fire. It also makes cooking uncomfortable as you might bump your head or feel the heat radiating back down.
• Too High: The suction becomes ineffective. Air follows the path of least resistance. If the hood is too high, cross drafts in the room from a fan or an open window will blow the smoke away before it reaches the filters.
For a standard gas stove, we recommend a distance of between 650 mm and 750 mm from the burner to the base of the hood. For electric or induction hobs, you can go slightly lower, around 550 mm to 650 mm, because there is no open flame.
You need to measure the distance from your countertop to your ceiling. Then subtract the recommended installation height. The remaining number is the space you have for the chimney unit itself. Most of our models come with telescopic duct covers that can be adjusted to fit various ceiling heights, but if you have a very low false ceiling or a very high loft style roof, you need to check the minimum and maximum height specifications of the unit.
Suction Capacity as a Size Metric
We often think of size in centimetres, but in the world of air movement, size is also volume. The "size" of the motor’s capability is measured in cubic metres per hour (m³/hr). This is arguably the most confusing part for buyers. How much suction do you actually need?
There is a scientific way to calculate this, and it relates directly to the size of your kitchen. The air in your kitchen needs to be cycled roughly 10 to 12 times an hour to keep it fresh during heavy cooking.
Here is a simple calculation you can do at home:
1. Measure the Length, Width, and Height of your kitchen in metres.
2. Multiply them to get the volume in cubic metres.
3. Multiply that volume by 12.
For example, if your kitchen is 3m x 3m x 3m, the volume is 27 cubic metres. Multiplied by 12, you get 324 m³/hr.
Now, you might look at that number and think that a 350 m³/hr chimney is sufficient. This is where theory meets reality. That calculation assumes a sealed room with perfect airflow. It accounts for neither the resistance of the duct pipe nor the bends in the pipe. It also ignores the fact that Indian cooking involves frying spices which releases heavy, oily smoke that requires much more force to move.
For an Indian kitchen, we almost always recommend looking at a suction capacity significantly higher than the theoretical minimum. A chimney size in terms of power should ideally be above 1000 m³/hr for anyone who cooks regularly. If you do a lot of deep frying or non-vegetarian cooking, looking at 1200 m³/hr or higher is wise. It ensures that even when the filter is slightly clogged or the duct has a bend, you still get adequate performance.
The Impact of Duct Sizing
This is the measurement everyone forgets until the installer arrives. The exhaust pipe that connects your chimney to the outside world has a specific diameter, usually 4 inches or 6 inches.
The rule of physics here is simple. You cannot push a large volume of air through a tiny hole without creating noise and back pressure. If you buy a high-suction chimney that moves 1200 m³/hr but connect it to a narrow 4-inch pipe, you are choking the machine. The motor will work harder, it will be louder, and the actual air movement will drop drastically.
Most high-performance chimneys require a 6-inch duct. Before you buy, check the hole in your wall. If your builder has left a 4-inch hole, you have two choices. Widen the hole or use a reducer, although the latter will compromise performance. Ideally, avoid forcing a large chimney size output into a small duct without understanding the trade-offs.
Island Kitchens: A Different Set of Rules
If you are one of the lucky ones with an island kitchen, where the hob is on a central counter, the rules for chimney size change slightly. In a wall-mounted setup, the wall acts as a guide for the smoke, helping to channel it upwards. On an island, the smoke is free to drift in any direction. Cross breezes affect it from all sides.
Because of this, an island chimney needs to be wider and more powerful than its wall-mounted counterpart to do the same job. If you have a 60 cm hob on an island, we strongly advise considering a 90 cm island chimney. You need that extra canopy width to compensate for the lack of a back wall. The height positioning is also more critical here. It needs to be high enough so you can see across the room but low enough to catch the fumes. This is a delicate balance that often requires professional planning.
Why Getting the Size Wrong Costs You Money
It is tempting to save money by buying a smaller unit or one with lower suction. But the cost of a wrong chimney size is hidden and cumulative.
If the unit is too small, grease bypasses the filters and settles on your expensive kitchen cabinets, your ceiling, and your curtains. Over a year, the cost of cleaning supplies, repainting, or replacing grime-coated fabrics can easily outweigh the difference in price between a correct-sized chimney and a compromised one.
Furthermore, an undersized motor has to run at maximum speed all the time to cope. This wears out the bearings faster and uses more electricity than a larger motor running comfortably at medium speed. It is similar to a car engine where a small engine screaming at high RPMs wears out faster than a big engine cruising along.
The Aesthetic of Proportion
Finally, let us briefly return to looks. A chimney is a large appliance. It creates a focal point. From a design perspective, proportion is key. A tiny 60 cm chimney hovering over a large cooking range looks unbalanced and spindly. Conversely, a massive 90 cm hood squeezed into a tiny kitchenette can look overwhelming and top-heavy.
When you plan your kitchen layout, draw the elevation. See how the chimney size relates to the cabinets on either side. We design our products to be visually pleasing by using tempered glass, sleek steel lines, and unobtrusive controls. But they need to sit in harmony with your other furniture.
If you are opting for a wall-mounted unit between cabinets, leaving a tiny gap of 2-3 mm on either side is practical for cleaning and vibration, but large gaps can look unfinished. If you are going for a standalone look without adjacent cabinets, a wider chimney often looks more luxurious and intentional.
Summary Checklist for Buyers
Before you head to a showroom or click buy, have this checklist ready:
• Hob Width: Is it 60 cm, 75 cm, or 90 cm?
• Cabinet Gap: What is the exact space available between wall units?
• Duct Hole: What is the diameter of the existing outlet in the wall?
• Ceiling Height: What is the vertical clearance available?
• Cooking Style: Heavy frying requires high suction while light boiling needs standard suction.
Getting the chimney size right is the foundation of a clean kitchen. It is the difference between a device that just makes noise and a device that keeps your home fresh. Take the tape measure out, get the numbers right, and you will thank yourself every time you walk into a kitchen that smells of nothing but fresh air. At Kaff, we believe that technology should fit your life rather than the other way around, and it starts with a perfect fit.
The Hidden Importance of Makeup Air
There is one final concept that often gets missed in size conversations, and that is makeup air. A chimney is essentially an air pump. It removes air from your kitchen. But for it to remove air, new air must come in to replace it. If you have a tightly sealed modern apartment with double-glazed windows and excellent insulation, a powerful 1200 m³/hr chimney can actually create a vacuum effect.
When this happens, the chimney struggles to suck air out because there is no air coming in to push it. It is like trying to suck a milkshake through a straw when the cup is sealed tight. You might notice doors becoming hard to open, or the chimney making a straining noise.
The solution lies in better airflow management rather than a smaller chimney. When you run a high-power chimney, you need to crack a window open slightly or ensure there is a ventilation path from another room. This allows the cycle of air to move freely. We design our motors to be robust, but they rely on this basic law of physics to function at their peak.
Understanding this relationship between the size of the motor and the "breathability" of your home ensures you get the performance you paid for. It is a small detail, but it separates a professional installation from an amateur one.
Maintenance and Long-Term Sizing
Size also dictates maintenance. A larger chimney often means larger filters or more filters. This can be a good thing. Larger surface area means the filters take longer to clog up compared to a smaller unit doing the same amount of work.
However, you also need to consider the physical size of the filters relative to your sink. Can you easily fit the baffle filters into your kitchen sink for scrubbing? If you have a compact sink and a massive 90 cm chimney with large single-piece filters, cleaning day becomes a chore.
Many of our larger 90 cm models come with split filters specifically to address this practical issue. It is a design choice we made after observing how real people clean their kitchens. When you are measuring for size, think about the cleaning process too. Will you need a stepladder to reach the controls? Is the oil collector tray accessible without contorting your body?
These ergonomic dimensions are just as real as the width and height. A chimney that is easy to reach and easy to clean is a chimney that stays efficient for years. One that is awkwardly sized or positioned tends to get neglected, leading to performance drops and eventual breakdowns.
Final Thoughts on Future-Proofing
Kitchens are long-term investments. You generally do not remodel them every two or three years. Because of this, we always advise sizing for the future, not just for today.
You might be a family of two right now cooking light meals. A 60 cm, moderate-suction chimney seems fine. But five years down the line, if your family grows or you start entertaining more, that same unit might feel inadequate. It is much harder to upgrade a chimney later because you might have to cut cabinets, widen duct holes, or move electrical points. It is far easier to install a slightly more capable unit today.
Think of the chimney size as a capacity buffer. Ideally, you have reserve power available for when you need it. You might run your chimney on speed 1 most days, but when you burn the toast or decide to fry fish for a dinner party, you will be grateful for the extra width and the extra suction power that a properly sized unit provides.
We build Kaff chimneys to last. By taking the time to measure correctly and understanding the nuances of width, depth, height, and power, you ensure that this appliance serves you faithfully for the decade to come. It is about precision, foresight, and the simple joy of a smoke-free home.
