Many of our customers are looking to buy coilovers or lowering springs for their car. Half of the manufacturers show their spring rates as kg/mm while others show them as lbs/in. It’s easy to forget what the conversion is so we put together a quick and easy chart to use for reference.
Roughly 1 KG/mm is equal to 55.997 LBS/in. Easy way to remember is 1 KG/mm = 56 LBS/in.
Here’s a few quick charts:
700 lb/in = 12.5 kg/mm
650 lb/in = 11.6 kg/mm
600 lb/in = 10.7 kg/mm
550 lb/in = 9.8 kg/mm
500 lb/in = 8.9 kg/mm
450 lb/in = 8 kg/mm
400 lb/in = 7.1 kg/mm
350 lb/in = 6.2 kg/mm
300 lb/in = 5.3 kg/mm
250 lb/in = 4.5 kg/mm
kg/mm to lbs/in
—————————–
16 = 896
15 = 840
14 = 784
13 = 728
12 = 672
11 = 616
10 = 560
9.0 = 504
8.5 = 476
8.0 = 448
7.5 = 420
7.0 = 392
6.5 = 364
6.0 = 336
5.5 = 308
5.0 = 280
4.5 = 252
4.0 = 224
3.0 = 168
2.0 = 112
Hope you guys find this helpful! Let us know if you have any questions about these numbers.
Very nice explanation. Simple and a great help to me today.
Thanks for taking the time and sharing with the rest of us. This has been very helpful on many occasions as a go-to guide. Keep up the good work.
Mike D.
So if I weight 200lbs what spring rate should I choose?
4.0, but that almost doesn’t make sense, because it’s pounds oer inch and I’m not going to be tour math teacher!
Very useful. Thank you!
how can i calculate “K” value if i have kgf. of spring
Here you go… straight from Google search!
The kilogram-force is a unit of measurement of force
The kilogram-force is a metric unit of force (kgf). The kilogram-force is equal to a mass of one kilogram multiplied by the standard acceleration due to gravity on Earth, which is defined as exactly 9.80665 meter per second²
My Kw springs say 120/170 what does this mean?
My question is this, can you put a 2.5 inch spring 12 inches tall. On a honda that calls for a 70 km spring. It is for a circle track racecar. Thank you