If you are buying a Herman Miller Aeron, the most important decision you will make is choosing the right size. Unlike most ergonomic chairs that rely on adjustable seat pans and sliding backs to fit different bodies, the Aeron comes in three distinct sizes: A (Small), B (Medium), and C (Large).
To get the right fit, you need to match your height and weight to the correct size bracket. If you are between 157cm and 183cm tall (5'2" to 6'0") and weigh under 158kg, Size B is the right choice. Size A is designed for smaller frames under 162cm, while Size C is built for taller or broader users up to 198cm.
Choosing the wrong size means the chair's famous 8Z Pellicle mesh will not support your body correctly, and the hard plastic frame may dig into your legs or shoulders. This guide explains exactly how to find your perfect fit.
Why Does the Aeron Come in Three Sizes?
When Bill Stumpf and Don Chadwick designed the original Aeron in 1994, they made a radical decision. Instead of building one highly adjustable chair with a sliding seat depth and moving backrest, they built three separate chairs.
This approach allowed them to stretch the Pellicle mesh suspension perfectly across a rigid frame. If the seat could slide forward and backward, the tension of the mesh would be compromised. By offering three fixed sizes, Herman Miller ensured that the ergonomic support, weight distribution, and breathability of the mesh remained optimal for every user.
When the chair was remastered in 2016, this A, B, and C sizing system was retained because it remains the most effective way to provide tailored support.
The Herman Miller Aeron Size Chart
The easiest way to find your size is to check where your height and weight intersect.
| Your Height | Your Weight | Recommended Aeron Size | |-------------|-------------|------------------------| | Under 157cm (5'2") | Under 68kg | Size A (Small) | | 157cm to 162cm (5'2" - 5'4") | Under 68kg | Size A or B | | 162cm to 183cm (5'4" - 6'0") | Up to 158kg | Size B (Medium) | | 183cm to 190cm (6'0" - 6'3") | Up to 158kg | Size B or C | | Over 190cm (6'3") | Up to 181kg | Size C (Large) |
Note: The B-size chair is designed to fit the broadest range of people. If you fall into an overlapping category (A/B or B/C), the larger size usually provides a more comfortable fit, especially if you have broader shoulders or longer legs.
Size A: For Smaller Frames
Size A is the smallest Aeron, designed specifically for petite users. It features a narrower seat, a lower backrest, and a shorter seat depth.
- Seat Depth: 406mm (16 inches)
- Max Weight Capacity: 136kg (300 lbs)
- Best for: Users under 157cm tall.
If you are petite, choosing Size A ensures that the front edge of the seat will not cut off circulation behind your knees. It also ensures the armrests can adjust narrow enough to support your arms while typing.
Size B: The Standard Fit
Size B is the medium Aeron and the most popular size by a significant margin. It is engineered to fit the majority of the adult population.
- Seat Depth: 432mm (17 inches)
- Max Weight Capacity: 158kg (350 lbs)
- Best for: Users between 162cm and 183cm tall.
If you are buying chairs for a shared office or a hot-desking environment where multiple people will use the same chair, Size B is the safest and most versatile choice.
Size C: For Taller and Broader Users
Size C is the plus-size model. It has a significantly wider seat pan, a deeper seat, and a taller backrest to support broader shoulders.
- Seat Depth: 470mm (18.5 inches)
- Max Weight Capacity: 181kg (400 lbs)
- Best for: Users over 190cm tall, or users with broader builds who need more width between the armrests.
If you have long legs, Size C is crucial. If you sit in a Size B and your legs are too long, the seat will feel uncomfortably short, leaving too much of your thigh unsupported. Size C provides the necessary depth to distribute your weight properly.
How to Check Which Size You Already Have
If you are buying a second-hand Aeron, or if you already have one in your office and want to order another of the same size, it is very easy to check which model you have.
Reach your hand under the top edge of the backrest frame, directly behind the Herman Miller logo. Run your fingers along the plastic lip. You will feel small raised bumps, similar to Braille:
- 1 dot = Size A
- 2 dots = Size B
- 3 dots = Size C
What Happens If You Choose the Wrong Size?
Because the Aeron has a rigid plastic frame holding the mesh in place, sizing mistakes are immediately noticeable.
If you buy a chair that is too small, the plastic side bolsters of the seat pan will dig into your thighs, and the top of the backrest will hit your shoulder blades uncomfortably.
If you buy a chair that is too large, the front lip of the seat pan will press into the back of your knees, cutting off circulation and causing leg numbness. The armrests may also be too far apart for comfortable typing.
If you are on the borderline between two sizes, the general rule of thumb is to look at your build. If you have a wider frame or longer legs, size up. If you have a slimmer build, size down.
Ready to Find Your Fit?
Choosing the right Herman Miller Aeron is an investment in a decade or more of comfortable, focused work.
At Chair Dinkum, we carry the full range of Herman Miller Aeron Chairs in Graphite, Mineral, and Onyx finishes, with all three sizes available.
If you are outfitting a commercial office or need help deciding between sizes for your home workspace, contact the Chair Dinkum team for practical, Australian-based advice.
Frequently Asked Questions
Does the Aeron chair have an adjustable seat depth? No. Unlike chairs such as the HÅG SoFi or Steelcase Gesture, the Aeron has a fixed seat depth. This is why it is sold in three different sizes (A, B, and C).
Are the armrests different on each size? Yes. The width between the armrests scales with the chair size. Size A has the narrowest distance between arms, while Size C is the widest. All Remastered Aerons sold by Chair Dinkum feature fully adjustable arms (height, depth, and pivot).
Can I change the size of my Aeron later? No. The frame, base, and mesh are all sized specifically to the A, B, or C specification. You cannot upgrade a Size B to a Size C by changing parts.
Is the Aeron suitable for Australian home offices? Absolutely. The breathable 8Z Pellicle mesh makes the Aeron exceptionally well-suited to the Australian climate, preventing the heat buildup common with traditional foam and fabric chairs during summer.
