formula for strength gain?

I was wondering if there was kind of a formula or maybe just a fact that tells you how much strength you can gain in a specifiy amount of time? I mean "endurance-strength", so more pull.ups, longer L-Sits etc.

How long does it take to double the strength if you are a beginner and able to do let's say 6 pull-ups?
Is there a formula?

 

This varies greatly based on genetics, body type, age, beginning strength, previous training, frequency and intensity of training, nutrition, amount of sleep you get and a myriad of other factors. Its very variable, and to the best of my knowledge, there is no formula - only approximations. For a healthy adult male to do 6 pullups... maybe 1-2 months. Using the 20 pullup challenge, I was doing ~10 after 2 months when I started, with my starting strength being a grand total of 0 pullups (I started by doing rows and elevated rows to get up to doing pullups). For females, possibly much longer - for example, see how the marine corps had to cancel plans to institute a 3 pullup minimum instead of flexed arm hang for females physical fitness test. Around half of the females weren't doing 3 pullups after having foreknowledge of the change for the better part of a year.

lisiflex said:

Is there a formula?

 

Nope.

Seabird said:

... the marine corps had to cancel plans to institute a 3 pullup minimum instead of flexed arm hang for females physical fitness test. Around half of the females weren't doing 3 pullups after having foreknowledge of the change for the better part of a year.

That makes me cross. Some butts need kicking!