How much space goes between the counter and the upper cabinets
Eighteen inches, almost everywhere, which puts the undersides of your wall cabinets 54" off the floor. Five minutes on why it is 18 will tell you when to use 15 or 20 instead, and it separates the one number on this wall that you may not change from the several that are yours to set. Inches first, millimetres in brackets.
Leave 18" (457 mm) between the countertop and the bottom of the wall cabinets. Anything from 15 to 20" is in normal use, and the difference is a straight trade between working room and reach. Above a cooktop the number is not yours to pick: building code calls for 30" (762 mm)of clearance to a combustible surface, which is why the cabinet over a range is a short 18"-tall box. A microwave mounted over the counter should have its bottom no higher than 54" (1372 mm) off the floor, or you are lifting hot liquid above your own shoulders.
Why 18 inches, specifically
Most answers to this question miss the reason. Nobody wrote 18" down as a rule. It is an arithmetic leftover that turned out to be comfortable, and then stuck because of what it lines up with.
Stack the standard kitchen and see where it lands. A base cabinet is 34½". A countertop is about 1½". Add the 18" gap and the wall cabinets begin at 54". That 54 is the number the rest of the kitchen is built around: add a 30" wall cabinet and you finish at 84", a 36" one and you finish at 90", a 42" one and you finish at 96", the three standard heights for a pantry or tall cabinet. Line a run of wall cabinets up against a pantry and the tops meet exactly.
The gap does two jobs at once. It is the room you need to work on the counter without knocking your knuckles, and it is the shim that makes the whole vertical grid close. Change it and you have moved the top of the room as well as one shelf. The full dimension grid shows the rest of that arithmetic.
A third reason it survived is prosaic. Eighteen inches is a convenient backsplash, taking a whole number of standard tiles in most common sizes, which means fewer cut edges along the top where the cut shows.
15, 18 or 20: what each one costs
Builders fit all three every day. The trade is always the same: room to work at the counter, against how far you can reach into the cabinet.
Gap
Reads as
What you gain
What it costs
15" (381 mm)
Tight
Three more inches of cabinet, and the top shelf comes into easy reach
A kettle, a stand mixer or a tall blender may not clear the counter, so small appliances live somewhere else
18" (457 mm)
The default
Room to work, room for a coffee machine, and a backsplash that takes a clean tile layout
Nothing in particular. This is the compromise everything else is measured against
20" (508 mm)
Open
Airy, generous backsplash, comfortable for a taller cook at the counter
The top shelf goes out of reach for most people, and the run reads top-heavy on an 8-foot ceiling
The practical test is the appliance you leave out on the counter. Stand your tallest one, the kettle with its lid open, the coffee machine with the hopper you have to fill, the stand mixer with the bowl raised, and measure it. If it needs more than 18", you have found your number, and the honest answer is to give that appliance its own stretch of wall rather than raising every cabinet in the kitchen by two inches.
Above the cooktop, the number is not yours
Everything above is convention. This part is not.
Building code requires 30" (762 mm) of clearance from the cooking surface to an unprotected combustible surface above it, and a wooden or board cabinet is a combustible surface. That is why a standard run puts a short cabinet over the range, an 18" tallbox instead of a 30" one, so its underside sits high enough above the burners.
Two things follow that people get wrong:
A hood is not a cabinet.Range hoods are appliances with their own tested mounting heights, and the maker's installation instructions govern, typically somewhere between 24 and 30" above the cooktop depending on the model and on whether the range is gas or electric. Follow the manual rather than a number you read somewhere.
An over-the-range microwave is also an appliance, with a specified mounting height of its own. It generally sits lower than a plain cabinet would be allowed to, because it is built and listed for that position.
The rule of thumb: if what is above the burners is furniture, the clearance is code. If it is an appliance, the clearance is the manufacturer's.
The microwave rule that has nothing to do with fire
Wherever the microwave goes, over the range, in a wall cabinet or in a tall unit, the useful guideline is that its floor should be no more than 54" (1372 mm) above the ground, the same line as the underside of the wall cabinets.
The reason is what comes out of it. You take a bowl of boiling soup out of a microwave with your arms extended, and above shoulder height you cannot see into the container or control the tilt. A microwave mounted high is the appliance most likely to scald someone in the kitchen, and the fix costs nothing at the design stage.
The gap and your height
The 18" convention assumes the 36" counter, and the 36" counter assumes an average adult. If you have already decided to move the work surface, and there are good reasons to, decide what the gap does at the same time. You have two separate choices and they interact:
Hold the gap and let the wall cabinets follow. Raise the counter an inch, raise everything an inch. The working relationship stays exactly as designed. Best when you are the cook and the top shelf is reachable for you.
Hold the wall cabinets and let the gap absorb it. Lower the counter two inches and the gap becomes 20". The cabinets stay where anyone can reach them, and the backsplash gets taller. Best in a shared kitchen where two people of different heights both use the wall cabinets.
For a shorter cook there is a third move worth more than either: keep the gap, and choose a shorter wall cabinet hung lower rather than a tall one whose top shelf is decorative storage. A 30" cabinet you can empty beats a 42" one whose top foot holds a vase.
Set the gap and see the whole wall move
The distance between counter and wall cabinets is not a note on a drawing. It decides where the cabinets hang, how tall they can be and where the run finishes against the ceiling. Change it in the editor and the elevation redraws, so you can see the top shelf leave your reach before anyone drills a wall.
How much space should be between countertop and upper cabinets?
18 inches (457 mm) is the standard, which places the undersides of the wall cabinets 54 inches off the floor. Fifteen to twenty inches is all in normal use. A smaller gap gives you a taller cabinet with a more reachable top shelf but less clearance for anything you keep out on the counter; a bigger gap is airier and more comfortable to work under, at the cost of pushing the top shelf out of reach. The exception is over a cooktop, where building code sets the clearance rather than preference.
Why is 18 inches the standard gap?
It is mostly an arithmetic leftover that turned out to be comfortable. A 34½ inch base cabinet plus a 1½ inch countertop plus 18 inches puts the wall cabinets at 54 inches, and 54 plus a 30, 36 or 42 inch wall cabinet gives exactly the 84, 90 and 96 inch heights that tall cabinets come in, so a run of wall cabinets finishes flush with a pantry. It also happens to be a convenient backsplash height that takes a whole number of standard tiles, which means fewer visible cut edges.
How high should wall cabinets be off the floor?
54 inches (1372 mm) to the underside, in a kitchen with standard 34½ inch base cabinets and an 18 inch gap. If your counter height is not standard, work from the counter rather than from the floor, since what matters is the room you have to work in and the reach into the cabinet rather than the absolute height. In a kitchen with no base cabinets underneath, such as a wall of uppers on their own, hang them to suit the reach of whoever uses them.
How far above a stove should a cabinet be?
Building code calls for 30 inches (762 mm) between the cooking surface and an unprotected combustible surface above it, and a board cabinet is combustible. That is why kitchens use a short cabinet, typically 18 inches tall rather than 30, over a range. If what sits above the burners is an appliance rather than a cabinet, such as a range hood or an over-the-range microwave, follow that appliance's own installation instructions instead; hoods are commonly specified somewhere between 24 and 30 inches above the cooktop depending on the model and the fuel.
How high should an over-the-counter microwave be?
Its floor should be no higher than about 54 inches (1372 mm) off the ground, the same line as the undersides of the wall cabinets. This is about what you take out of it rather than clearance: lifting an open container of boiling liquid above shoulder height means you cannot see into it or control the tilt. It is the most common way people get scalded in a kitchen, and it costs nothing to avoid while the design is still a drawing.
Can I make the gap bigger to fit my coffee machine?
Yes, and the sensible version is to make it bigger in one place rather than everywhere. Measure the appliance in its worst state, the kettle with its lid open or the machine with its hopper being filled, and if it needs more than 18 inches, give that appliance a dedicated stretch of counter with a shorter cabinet or no cabinet above it. Raising every wall cabinet in the kitchen by two inches to solve one appliance costs you reach along the entire run, and on an 8-foot ceiling it can push the tops past where a standard cabinet height lands cleanly.
Does the gap change if my counters are a custom height?
You get to choose, and the choice is a real one. Holding the gap and letting the wall cabinets move with the counter keeps the working relationship exactly as designed, which suits a kitchen with one main cook. Holding the wall cabinets and letting the gap absorb the change keeps the cabinets reachable for everyone, which suits a shared kitchen, since a two-inch lower counter simply becomes a 20 inch backsplash. For a shorter cook specifically, a shorter wall cabinet hung at a comfortable height beats a tall one whose top shelf can only be reached from a stool.
