You need torque to achieve tension, but the two values do not easily correlate.
In simple terms, torque is the effort or power required to spin the nut down the threads of a bolt. While tension is the stretch of the bolt that produces a clamping force in the steel.
The biggest problem with trying to equate torque to tension is that torque is affected by the friction between the threads of a nut and bolt, as well as between the turning element and flat washer.
Since every bolt assembly is unique to its lot combination and condition, a single torque value will give you unlimited results in achieved tension.
Now I could go on and on writing about friction factors, K Values, T=PKD, bolt conditions, storage, rust and lube to help explain the differences between Torque and Tension. It will just be so much easier for you to go watch this video : )
Check out our Wrench Selection page to to ensure you are choosing the correct size tool with enough torque to get the job done.