When you purchase springs the spring measurements (4", 6", 8",etc) represent the approximate uncompressed height of the spring when you purchase it. Once you tie the springs they will be shorter. The chart below gives you a rough idea of what the height of the springs might be after they are tied. The actual height after they are tied will vary, as described below.
Height of Upholstery Seat Springs after they are tied (compressed)
This chart is intended to help you choose the approximate correct size of upholstery springs.
Here are the approximate sizes and compression ranges to upholstery coil springs for seats. Pick a spring size where the mid point is the nearest to your desired height. These seats springs are available in either 9 gauge medium or 8 gauge firm springs. The sizes are not meant to be an exact representation, but only an approximate height. There is a lot of room for variance in the height of each upholstery spring. If the height of the springs are a little too high for the space you can tie the springs down tighter, or you can reduce the amount of padding on top of the springs. If the springs are a little shorter than your desired height, don't tie them down quite as tight, or add more padding on top of the springs.
Lowest point represents the height after the springs at pulled tightly down to their approximate lowest point.
Mid Point represents the idea (mid range) height of the springs after their are tied. Use the midpoint to choose your desired spring height.
Highest point refers to highest (or loosest) point at which the springs might be tied.
|Height Uncompressed||Approximate Heights After Compression*|
|Spring Size||Lowest point*||Mid point*||Highest point*|
|4" Tall Spring||3"||3 1/4"||3 1/2"|
|5" Tall Spring||3 1/4"||3 1/2"||4"|
|5 1/2" Tall Spring||3 1/2"||4"||4 1/2"|
|6" Tall Spring||4"||4 1/2"||4 3/4"|
|7" Tall Spring||4 1/2"||5"||5 3/4"|
|8" Tall Spring||5"||6"||6 1/2"|
|9" Tall Spring||6"||7"||7 1/2"|
|10" Tall Spring||7"||8"||8 1/2"|
|12" Tall Spring||9"||9 1/2"||10"|
*Don't take the compressed height measurements too literally. Compression will vary depending upon spring wire gauge and the firmness of the springs. Use this chart only as a rough approximate guide.
Upholstery Springs are available in most of these sizes listed in the chart. However, most suppliers only carry a few of the sizes. If your supplier doesn't carry the size you need, you may need to contact some other suppliers.
Controlling the firmness of the springs in the seat.
There are several ways to control the firmness or softness of the seat springs.
First, you can order a firm, medium, or soft springs.
Secondly, you can control the firmness by how tight you compress the springs when you tie them. The more you compress the spring (such as to the lowest point on the chart), the firmer the springs will be.
Third, you can control the firmness or softness of the seat by how you space the springs. The closer the springs are to each other, the firmer the seat. The further away the springs are from each other, the softer the seat.
Gauge on springs
Generally the lower the number the firmer the spring (although there are exceptions, check with the supplier to be sure.)
- The 8 gauge springs are the firmest grade,
- 9 gauge come are the next firmest. However 9 gauge also comes in medium and firm, so check when one you are getting when you order them.
- 13 guage springs are very soft that are used in the backrests of the furniture.
Types of Upholstery Coil Springs
Upholstery coil springs come in at least two types. One type has the wire loose at both ends. The other type has one end of the wire knotted. I prefer the type with the knotted end. When you place the springs in the furniture, always put the knotted end at the top.
Spacing of Springs
The circled ends of upholstery spring are approximately 4 1/2 in diameter. In theory, the springs can be spaced anyway from about 5 1/2" to 8" or more (measured center to center.) The actual spacing will be determined by the measurement of the seat area and the desired firmness of the seat area. There is no hard fast rule as to exact spacing. However, here are some guidelines. The edges of the springs are generally about 1" inside the bottom of the arm frame
The firmness of the seat can be controlled in two ways. One, is to purchase either medium or firm springs, depending upon your what you choose. The other way to control the firmness of the spring is in the spacing. To build a firmer seat, space the springs very close together, with perhaps 1-2" inches between the springs. To build a softer seat, space the springs further apart, from 2-4" (or further) apart.
Before Purchasing the springs
If you are unfamiliar with the height of the springs I'd recommend that you first purchase 3 springs, one spring that is the height that you think you want, then buy one taller and one shorter spring. Then take them back to your shop and test each one to see which one seems best suited for the height that you want.
Testing The Spring Height
You test the spring by putting your hand flat on the top of the spring and pushing down. The spring pushes down fairly easily for the first inch or two (depending on the uncompressed height of the spring). Then, as you continue to press down you will find that the spring begins to push back up against your hand. It's at the point where you feel the spring press firmly up against your hand that will be the compressed height of the spring. Measure that height. This is not an exact science. This just give you an approximate finished height for your springs, and that measurement will vary a little, and that's OK.