I’m a big fan of designing my projects based upon proportions. Not that I have an issue with a dimensional approach, I just find proportions give me a framework within to work. Up to this point my designs have begun with some sort of controlling dimension or distance. Then everything else is proportioned around that. In the book, “By Hand and Eye“, one of the concepts presented is to proportion items based upon your own body. The base module (controlling dimension) is the span of your hand. Using this base module, you can then derive distances proportionally based upon your individual body. Your hand span happens to also coincide with the height of your head.
Breaking the body down proportionally based on head height is nothing new. It can be traced back easily to Leonardo Da Vinci’s “Vitruvian Man“. Artists are quite familiar with this and the system has been used for centuries to teach drawing of the human figure.
In “The Anarchist’s Design Book“, Christopher Schwarz recommends a book on anthropometrics entitled, “Human Dimension & Interior Space“. Essentially a textbook for interior designers that covers just about every human interaction with interiors and their furnishings. So I ordered a copy and began going thru it. Not exactly light reading, but full of useful information.
I have several projects on my list that are some version of a table or of seating and I want these pieces to have a cohesive feel and to function interchangeably. For example, the dinning chair can function as a desk chair or vise versa. So combining the proportional breakdown of the human body and the information from the book on anthropometrics, I created a reference sheet for table and seating proportions. Specifically addressing height and depth since those distances are typically the most critical to function. I’ll use this reference to establish these heights and depths based upon my own individual height. I happen to fall in the median range at 1776mm (~70″) tall, so what I build based on my height should function for a wide range of people.
OK, it’s not quite on par with Da Vinci’s work, but it will be a handy reference when designing pieces of this type. I deliberately kept the notation as sparse as possible. The drawing stands on its own (hopefully), but I’ll go over a little of what it is depicting. I’ll also add in the actual dimensions. I won’t typically use numerical dimensions, but I think they will help you to understand what I’m doing here.
The grid is comprised of 1M(module) squares. Three of these squares I divided proportionally to derive 1/2M, 1/3M, 1/4M, 1/5M, 1/6M, 1/8M and 1/10M.
Based upon my height of 1776mm (~70″), my module works out to be:
At the center bottom of the drawing I depict a step stool. The most comfortable stepping height for most people equals their head height (M). So the height of the step stool is shown as 1M(222mm). The depth of the step stool should be slightly longer than the length of your foot (1/6 of your height). I have worked this out to be 7/5M(311mm).
Step stool=1M(222mm)H x 7/5M(311mm)D
Step stool=1M(8.74″)H x 7/5M(12.24″)D
At the far right I have depicted a chair. The recommended height for seating is that the platform should be at popliteal height, the height where the bottom of your thigh meets the back of your knee when the leg is bent at 90°. This height is equal to the height of two heads or 2M(444mm). The depth a chair should be slightly less than the popliteal length, the length from the back of the lower leg to the rearmost surface of the buttock. I have depicted this in two ways. First being a full 2M(444mm). This being applicable where the back of the chair will be attached to the seat inset from the rear. Spindles for staked chairs being an example. Where the back will be flush to the rear of the seat, the seat depth is reduced to 9/5M(400mm). The height of the crest rail can be quite variable. I have depicted it at 2M(444mm) above the seat. This will bring the crest rail to just below shoulder level.
Chair=2M(444mm)H x 9/5M(400mm) usable depth
Chair=2M(17.48″)H x 9/5M(15.75″) usable depth
The height for a table that you will be seated at is a little more difficult to explain. Jim Toplin recently wrote a post on table heaight and is worth a read. After a little trial and error, I came up with a height of 3M + 1/3M or 10/3M(740mm). The depth of a table can be quite variable depending on function. Will it be for dining, a desk or maybe a dedicated work station? I have depicted the maximum depth of table that my dining room can handle, 4M(888mm).
Table (seated)=10/3M(740mm)H x (variable depth)
Table (seated)=10/3M(29.13″)H x (variable depth)
The height of a table for standing work is most useful at 4M(888mm) or half your height. What I have depicted here is that happy median. Height can be adjusted up or down as specific tasks dictate. The maximum comfortable reach for most people is 3M(666mm). That’s why most of us are working at workbenches that about 666mm (26.22″) deep or slightly less.
Table (standing)=4M(888mm)H x 3M(666mm)D
Table (standing)=4M(34.96″)H x 3M(26.22″)D
If you get tired of standing at the table, you will need a stool. After some experimenting I found that a height of 5/4M(278mm) below the height of the standing work table height. When compared to the standing work table depicted above, the stool height works out to be 11/4M(611mm). The depth of the stool seat needs be narrower than that of a chair. A full depth (9/5M=400mm) seat on the stool runs the risk of creating a pinch point at the back of the knee. So I have established a depth for the stool seat, as well as benches, to be 3/2M(333mm). There also needs to be a foot rest 7/4M(388mm) below the seat height so the users feet are not left dangling.
Stool (tall)=11/4M(611mm)H x 3/2M(333mm)D
Stool (tall)=11/4M(24″)H x 3/2M(13.11″)D
None of these proportions/dimensions are set in stone, but will provide me with starting points. I have also made no mention of length. Length is quite variable and can be a result of function and/or design. As I design other pieces that don’t fit into the above categories, I’ll use this reference to determine how those new pieces will interact. Both with the above types of furniture and with myself.
So I hope that I haven’t confused you, but gave you something to think about.
PDF version of the reference sheet: tables_seating_proportions.pdf