The Herman Miller Aeron comes in three sizes. Size A fits people 142–163 cm tall and up to 136 kg, Size B fits 158–183 cm and up to 159 kg, and Size C fits 178–200 cm and up to 159 kg. If your height and weight land on a boundary, Herman Miller's own advice is Size B.
- Herman Miller builds the Aeron in three frame sizes, A, B and C, to cover the 1st to the 99th percentile of adult bodies.
- Seat depth is fixed per size at 40.6 cm (A), 43.2 cm (B) and 47.0 cm (C); the Aeron has no seat-depth adjustment.
- Maximum user weight is 136 kg for Size A and 159 kg for Size B and Size C on Herman Miller's size chart and US store; the 2026 Herman Miller EMEA product sheet lists Size C at 181 kg.
- Herman Miller's Size/Fit chart puts a 180–193 cm person weighing 72–122 kg in its B-or-C zone, and its printed advice for that zone is Size B.
- Every Aeron carries raised dots under the top edge of the back frame, opposite the logo: one dot is Size A, two is Size B, three is Size C.
- Every Aeron size comes in the same finishes and base options; the size letter changes the frame, not the specification list.
- No Aeron ships with a headrest; Herman Miller does not make one, and the add-on headrests sold for it are third-party.
Last updated October 2026. Specifications checked against Herman Miller's current documents in October 2026.
Aeron size chart in cm and kg
The figures below come from Herman Miller's Australian specification page, its 2016 Size/Fit Reference, its 2026 product sheet and its European store dimension table, converted to centimetres and kilograms where the source was imperial.
| Specification | Size A (small) | Size B (medium) | Size C (large) |
|---|---|---|---|
| Recommended user height | 142–163 cm | 158–183 cm | 178–200 cm |
| Maximum user weight | 136 kg | 159 kg | 159 kg (181 kg on the 2026 EMEA sheet) |
| Seat depth | 40.6 cm | 43.2 cm | 47.0 cm |
| Seat pan width | 47.5 cm | 51.4 cm | 54.2 cm |
| Width inside the arms | 43.0 cm | 47.0 cm | 49.8 cm |
| Backrest height | 47.8 cm | 53.0 cm | 56.1 cm |
| Seat height range | 36.6–49.0 cm | 37.6–57.9 cm | 40.1–57.9 cm |
| Overall height | 87.0–97.8 cm | 93.3–104.5 cm | 101.6–115.3 cm |
| Overall width (fixed or height-adjustable arms) | 69.8 cm | 71.9 cm | 71.9 cm |
| Chair weight | 18.1 kg | 18.6 kg | 19.5 kg |
| Size dots under the back frame | 1 dot | 2 dots | 3 dots in a triangle |
Two things to read into those rows. Size B and Size C share the same 159 kg rating on the 2016 Herman Miller size chart in both its US and UK editions, so moving up to a C changes the geometry, not the load the chair is warranted for. The only Herman Miller document we found that lists 181 kg is the 2026 European product sheet, and we plan around the conservative number. And if you weigh more than 136 kg, Size A is off the table regardless of your height.
Aeron chairs set up for back-to-back sit-tests at our Sydney showroom. Height and weight get you to the right row of the chart; ten minutes in the chair settles it.
What actually changes between Size A, B and C?
All three sizes use the same 8Z Pellicle mesh and offer the same arm, tilt and back-support options, so a bigger letter is not a better chair. What scales is the frame: Herman Miller's Australian product page lists backrest height, seat width, the tilt mechanism and the base diameter as the parts sized to each letter.
The row that matters most is seat depth, because the Aeron has no slider to fine-tune it. The 3.8 cm step between Size B (43.2 cm) and Size C (47.0 cm) is the whole reason the B-or-C question exists. Sitting fully back, you want about two fingers of clearance between the front edge of the seat and the back of your knee. Too little and the frame presses behind the knee; too much and your thighs lose support and the lumbar pad lands in the wrong place.
What does the Herman Miller size chart say at 180 cm?
Herman Miller's Size/Fit Reference is a grid of height against weight with five zones: A, A or B, B, B or C, and C. For an adult between 180 cm and 193 cm, the chart reads B only up to about 68 kg, B or C from 72 kg to 122 kg, and C only from about 126 kg. At 195–200 cm the C-only zone starts at roughly 90 kg. At 178 cm or under, the chart never recommends C only unless you weigh 117 kg or more.
Herman Miller’s Size/Fit zones redrawn in centimetres and kilograms. Find where your height and weight meet; the table below reads the same chart row by row.
| Your height | Chart says A or B | Chart says B | Chart says B or C | Chart says C |
|---|---|---|---|---|
| 160–175 cm | up to 72 kg | 72–77 kg | 81–113 kg | from about 117 kg |
| 178 cm | — | up to about 77 kg | 81–113 kg | from about 117 kg |
| 180–193 cm | — | up to about 68 kg | 72–122 kg | from about 126 kg |
| 195–200 cm | — | up to about 68 kg | 72–86 kg | from about 90 kg |
For the B-or-C zone the printed guidance is unambiguous: because Size B is designed to fit a broad range of people, Herman Miller "recommends it for users who fall in the A/B or B/C category". By the official chart, a 183 cm, 85 kg sitter is a Size B, and so is a 190 cm, 85 kg sitter. The same document notes that it exists for when you cannot sit in all three sizes, which is Herman Miller's way of saying the sit-test wins. One caveat: this is the 2016 chart with a 159 kg ceiling, and no revised chart reflecting the 181 kg figure has been published.
Size B or Size C: what owners actually report
The B-or-C decision between about 180 and 190 cm is the most common Aeron sizing question on Reddit's Herman Miller forum, and it turns up on OzBargain too. The complaints run in opposite directions. People who sized up to a C most often report that the deeper seat touches the inside of the knee, the pan feels too wide, and they cannot feel the lumbar support. People who stayed in a B at 185 cm and above most often report that the top of the backrest sits at the shoulder blades and that the front seat frame presses on the thighs.
In one OzBargain thread, a 180 cm, 85 kg buyer found the Size C oversized and the Size B snug enough to hold a correct posture; a 183 cm, 96 kg owner in the same thread had both and kept the B for 15 years. On our own showroom floors most 178–185 cm sitters of average build end up in a B, and the ones who choose a C usually have long thighs, broad shoulders or a heavier build.
Three checks we run in the chair settle it:
- Knee gap. Sit fully back. About two fingers of clearance between the seat edge and the back of your knee is right. If the edge touches your knee, size down.
- Shoulder-blade clearance. The top of the back frame should clear the bottom of your shoulder blades when you recline. If the hard frame lands mid-blade, the chair is too short for your torso.
- Thigh-rim pressure. The mesh is tensioned inside a firm frame. If the side or front rim presses into your outer thighs, that is a reason to size up independent of height.
Who should buy a Size A?
Under about 160 cm, take the Size A seriously. Its seat drops to 36.6 cm, 1 cm lower than a B, its 40.6 cm seat depth lets shorter legs reach the floor with the back supported, and the 43 cm span between the arms suits narrower shoulders. Herman Miller's chart places people 142–155 cm and up to 54 kg in A only; at 142–175 cm and up to 72 kg it reads A or B, and its default for that zone is B. Sit in both if you can.
How do I tell what size Aeron I have?
Reach under the top rail of the back frame, behind the Herman Miller logo badge, and feel for small raised bumps: one dot is Size A, two dots is Size B, three dots arranged in a triangle is Size C. You will feel them before you see them. The manufacturing label under the seat is where a second-hand buyer should look for the manufacture date.
If the dots are worn, measure the seat pan: about 47.5 cm wide is an A, 51.4 cm a B and 54.2 cm a C. Generation matters too. The Remastered Aeron launched in late 2016 with the 8Z Pellicle mesh, Harmonic 2 tilt and PostureFit SL; the Classic stayed orderable into early 2018 and is rated to 136 kg rather than 159 kg. For what to check before paying for a used chair, read our new vs used Aeron guide.
Two Aeron sizes side by side at our Melbourne showroom. Backrest height, seat width and seat depth all scale with the letter, which is why the chairs are not interchangeable.
Which Aeron sizes and finishes we stock in Australia
At Aussie Chair the Herman Miller Aeron is available in all three sizes, in Graphite, Mineral, Onyx, Carbon, Jasper and Nightfall, on a plastic, satin aluminium or polished aluminium base. Jasper (a dark olive green) and Nightfall (a midnight blue) are the two colours Herman Miller added for 2026. Every combination, with current pricing, is on the product page, and every chair we sell is brand-new and 100% genuine.
Every Aeron from us includes a 1-year warranty as standard, with the optional 12-Year Warranty Upgrade offered on the same page; our Herman Miller warranty guide explains what it covers. Sizes are not interchangeable after the fact, so choose the letter first and the finish second. Taller or heavier sitters weighing the Size C against purpose-built big-and-tall chairs can compare the options in our big and tall chairs guide.
Honest limits of the Aeron sizing system
Fixed seat depth is the Aeron's biggest sizing limitation. The three-size system exists because there is no slider, and the 3.8 cm step between B and C is why so many 180–190 cm buyers feel caught between the two. The firm frame rim can press on the outer thighs in any size, which is why the thigh-rim check above matters more than the chart. And no Aeron ships with a headrest: Herman Miller's position is that PostureFit sacral support makes one unnecessary, and that head and neck shapes vary too much for one headrest to fit everyone. If you want one, the Atlas headrest we stock is a third-party add-on that fits Size A, B and C, in Graphite, Mineral and Onyx.
Graphite, Mineral and Onyx Aerons at our Melbourne showroom, each fitted with the add-on headrest. The headrest is separate; the chair itself ships without one.
FAQ
What size Aeron should I get?
Match your height first: 142–163 cm points to Size A, 158–183 cm to Size B and 178–200 cm to Size C. Then check weight, because Size A is rated to 136 kg and Sizes B and C to 159 kg. If you land in an overlap, Herman Miller recommends Size B, and a sit-test is the only definitive answer.
How do I know what size Aeron I have?
Feel under the top edge of the back frame, opposite the Herman Miller logo, for raised dots: one dot is Size A, two dots is Size B, three dots in a triangle is Size C. If the dots are worn, measure the seat pan width: about 47.5 cm is an A, 51.4 cm a B and 54.2 cm a C.
Should I get an Aeron Size B or Size C at 180 cm?
At 180 cm, Herman Miller's chart reads Size B up to about 68 kg and B or C from 72 to 122 kg, and it recommends Size B in that zone. Choose the C only if you have long thighs or broad shoulders and the deeper 47 cm seat still leaves two fingers of clearance behind the knee.
Is the Aeron Size B or Size C better for a tall person?
Above 185 cm the Size B backrest often ends at the shoulder blades, and from 195 cm Herman Miller's chart moves to Size C from about 90 kg. Tall but light sitters, under about 68 kg, still chart into a B. Between 185 and 195 cm the deciding factors are torso length and weight, so sit in both.
What is the weight limit of a Herman Miller Aeron by size?
Herman Miller rates the Aeron Size A to 136 kg and the Size B and Size C to 159 kg on its size chart, its US store and Australian dealer pages. Its 2026 European product sheet lists the Size C at 181 kg. Moving from B to C changes the chair's dimensions, not its rating on the published chart.
Does the Herman Miller Aeron come with a headrest?
No. Herman Miller does not make an Aeron headrest and says its PostureFit sacral support makes one unnecessary. Third-party headrests such as the Atlas are made to fit Sizes A, B and C; at Aussie Chair the Atlas headrest is a separate add-on in Graphite, Mineral and Onyx.
Can I change the size of an Aeron after buying it?
No. The size is built into the frame, seat pan and backrest, so an Aeron cannot be converted from one size to another by swapping parts. Choose the letter first and the finish second, and sit-test if you are anywhere near a boundary, because the fit cannot be adjusted later.
Sit-test all three sizes before you choose
The chart gets you close; your body makes the final call. We keep Aerons on the floor at our Sydney showroom (Unit 11, 46-50 Wellington Rd, South Granville NSW) and our Melbourne showroom (Shop 1a/280 Whitehorse Rd, Nunawading VIC), so you can run the knee-gap, shoulder-blade and thigh-rim checks in person; visits are by appointment through our showrooms page. Already know your letter? Order the Aeron online, or browse the full Herman Miller range, with delivery across Australia and New Zealand.
