If you ever need to calculate spring rates...
The spring rate equation is k=(G*d^4)/(8*n*D^3)
where k is the spring rate, G is the modulus of rigidity, d is the wire diameter, n is the number of active coils, and D is the average diameter (inside diameter plus wire diameter).
Given that G is about 11.4 million psi for steel alloys, that reduces the equation to: k=(1425000*d^4)/(n*D^3),
If that's still too much for you this is about a simple as I can make the equation:
spring rate = (1425000*d*d*d*d)/(n*D*D*D)
Here's a handy online calculator:
Hint: As mentioned above, if the springs are pretty much any steel alloy you can use 11,400,000 for G "modulus of rigidity". All other variables can be easily measured at home from your springs.