The Herman Miller Aeron Medium (Size B) and Large (Size C) offer identical world-class ergonomic features, but they are engineered for different body types. The Medium is designed for users of average height and build (5'2" to 6'0"), while the Large provides essential extra space and support for taller or heavier individuals (5'8" to 6'6"). Your body size is the only meaningful factor when choosing between them.
Here's everything you need to know to choose the right Herman Miller Aeron chair for your body.
Herman Miller Aeron Chair (Size B - Medium)
The Aeron Medium, or Size B, is the most popular version of this iconic office chair and is considered the standard size. It's designed to provide tailored ergonomic support for the widest range of users, fitting average body heights and weights perfectly. It features the same breathable Pellicle mesh and PostureFit SL back support as the other sizes, but its dimensions offer a snug, secure fit that prevents slouching and promotes healthy posture for most people.
- What it is: The standard and most common size of Herman Miller's flagship ergonomic office chair.
- Key features: Breathable Pellicle suspension mesh, PostureFit SL adjustable sacral and lumbar support, fully adjustable arms, tilt limiter with forward seat angle adjustment, and durable aluminum frame.
- Recommended Fit: Designed for users between 5'2" and 6'0" in height and 130 lbs to 155 lbs in weight.
- Price: Approximately $1,200 - $1,500, depending on configuration and retailer.
- Materials/Construction: High-quality aluminum frame and base with a signature Pellicle mesh seat and back. Built to last and backed by a 12-year warranty.
- Pros: Provides a perfect ergonomic fit for the majority of users. Encourages proper posture with its snug seat design. High resale value. Class-leading build quality and warranty.
- Cons: Sizing is critical - it can feel too confining for larger individuals. The hard plastic seat frame can be uncomfortable for some users. Premium price point.
The Aeron Medium is the ideal choice for individuals with an average height and weight who need a no-compromise ergonomic chair for long hours of work.
Shop this product: hermanmiller.com/products/office-chairs/aeron-chairs/
Herman Miller Aeron Chair (Size C - Large)
The Aeron Large (Size C) offers all the same groundbreaking ergonomic features and high-quality materials as its smaller counterparts but in a more generously-sized package. It's specifically engineered for taller and heavier users who would find the Size B too restrictive. With a wider and deeper seat pan and a taller backrest, the Size C ensures that larger individuals receive the full benefits of the Aeron's advanced design without feeling cramped.
- What it is: A larger version of the Aeron chair designed for taller or heavier body types.
- Key features: Same as the Size B, including Pellicle mesh, PostureFit SL support, fully adjustable arms, and tilt limiter, but with increased dimensions.
- Recommended Fit: Designed for users between 5'8" and 6'6" in height and 180 lbs to 230 lbs in weight.
- Price: Approximately $1,200 - $1,500, with a minimal price difference compared to the Size B.
- Materials/Construction: Identical industrial-grade materials as the Size B, including an aluminum frame and Pellicle mesh, backed by a 12-year warranty.
- Pros: Provides a comfortable, spacious seat for taller and heavier users. Accommodates long legs with a deeper seat pan. Prevents discomfort associated with chairs that are too small. Excellent durability and support for higher weight capacities.
- Cons: Can feel too big for average or smaller users, potentially causing poor posture. Requires more floor space. Premium price point.
The Aeron Large is designed for individuals who require extra room and robust support to maintain proper ergonomic alignment throughout the workday.
Shop this product: hermanmiller.com/products/office-chairs/aeron-chairs/
Aeron Medium vs. Large Comparison
Dimensions & Fit
This is the most critical point of comparison. The choice between the Medium (Size B) and Large (Size C) comes down entirely to how the chair fits your body. The Size B is intended for people from 5'2" to 6'0", while the Size C serves those from 5'8" to 6'6". Notice the overlap between 5'8" and 6'0" - in this range, body weight and leg length become the deciding factors.
The Size C chair features a deeper seat pan, accommodating users with longer thighs and ensuring proper support under the legs. Its wider seat provides more room, which is essential for comfort for heavier individuals. Conversely, if you choose a chair that is too large, your feet might not rest flat on the floor, and you may not be able to sit with your back fully against the backrest, defeating the chair's ergonomic purpose.
Comfort & Ergonomics
Both chairs deliver the same world-class ergonomic experience - when correctly sized for the user. Features like the PostureFit SL system, which supports the sacrum and lumbar region, function identically in both models. The breathable Pellicle mesh contours to your body and prevents hotspots, regardless of size.
The difference in comfort comes from the fit. The Aeron Medium provides a secure, body-hugging support that many find great for maintaining good posture. The Aeron Large offers a more spacious feel, which is necessary for larger frames to feel comfortable rather than confined. Buying the wrong size will directly compromise your comfort and the chair's benefits.
Materials & Construction
There is absolutely no difference in quality between the Medium and Large Aeron. Both chairs are manufactured in the USA using the same premium materials, including a robust die-cast aluminum frame, high-tensile Pellicle mesh, and durable adjustment mechanisms. Herman Miller’s 12-year, 24/7-use warranty covers both sizes equally, testament to their confidence in the chair's longevity and craftsmanship.
Price & Value
The price discrepancy between the Aeron Medium and Large is negligible, often just a few dollars or nonexistent depending on the retailer and configuration. Your decision should never be based on cost. The true value of an Aeron chair is realized over its decade-plus lifespan of providing ergonomic support and comfort. That value is only achieved if you select the size that correctly fits your body, making fit the sole factor in determining the chair's value to you.
Who Each One Works Best For
The choice is purely functional. The Medium (Size B) is the default pick for most adults of average height and weight. It provides a finely tuned fit that is both comfortable and supportive for long work sessions.
The Large (Size C) is built for a specific need: providing proper ergonomic support to people who are taller, heavier, or have longer legs than the average user. If standard office chairs often feel cramped, too short, or not deep enough in the seat, the Size C is the correct solution.
Which One Should You Choose?
Both Aeron chairs deliver outstanding support but are tailored specifically to your body dimensions.
Choose the Aeron Medium (Size B) if:
- You are between 5'2" and 6'0" in height.
- You have an average build and find standard office chairs to be a good fit.
- You want a chair that offers a secure, body-contouring feel.
- You have sufficient space between the edge of the seat and the back of your knees (about 2-3 fingers' width).
Choose the Aeron Large (Size C) if:
- You are between 5'8" and 6'6" in height, especially if you're over 6'0".
- You are heavier than average or have a broader frame.
- You often feel that standard office chair seats are too narrow or not deep enough.
- You need more space to sit comfortably without feeling restricted by the seat frame.
Frequently Asked Questions
What's the main difference between the Aeron Size B and C?
The exclusive difference is the dimensions. The Size C (Large) has a wider and deeper seat pan, a taller backrest, and is designed to support taller and heavier users properly. The ergonomic features, materials, and warranty are identical across both sizes.
How do I know for sure which Aeron size to get?
Consult the official Herman Miller sizing chart. It provides precise height and weight ranges to help you choose between Size A (Small), B (Medium), and C (Large). If you fall in a crossover range (e.g., 5'9", 170 lbs), your personal preference for a snug versus spacious fit will be the deciding factor.
Is the Large Aeron better just because it's bigger?
No. An ergonomic chair is only effective if it fits you correctly. Choosing a chair that is too large can be just as detrimental as one that is too small, as it may lead to improper posture or lack of support where you need it.
What happens if I buy the wrong size?
If you purchase from Herman Miller or an authorized dealer, you typically have around a 30-day return window. If you buy the wrong size, you will likely feel uncomfortable - either cramped (in the Medium) or unsupported (in the Large) - and should return it for the correct size.
Do both sizes have the same features and adjustments?
Yes. Both the Medium and Large versions can be configured with the exact same features, including PostureFit SL support, fully adjustable arms, tilt limiter, and choice of caster wheels. The functional components are identical.
Is there a different weight limit for the Aeron Medium and Large?
Yes. The Size B (Medium) has a recommended weight capacity of up to 300 lbs, while the Size C (Large) is recommended for up to 350 lbs, providing extra structural support for heavier users.
Can two people of different sizes share one Aeron chair?
It depends on their sizes. If both individuals fall within the recommended range for either the Size B or Size C, it can work well. However, if one person needs a Size B and the other needs a Size C, the chair will only be ergonomically correct for one of them.
Does the seat height range differ between the Medium and Large?
The seat height adjustment ranges are very similar, designed to scale with the recommended user height. The Size B ranges from 16" to 20.5", while the Size C ranges from 16" to 20.5". The critical difference is not the height range, but the seat depth and width.
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