Why am i having different footing dimensions in staad pro foundation

Question

Why am i having different footing dimensions in staad pro foundation, while i am using the same loading but different codes. 
 I thought footing dimension is a function of reaction/soil bearing capacity? 
 
 please help

i noticed the minimum L&B British code can go is 1.3m

Kris Sathia · Answer

From the screenshot you attached, we see that you are running version 9.1.0.14. 
 The latest version of SFA is Build 9.2.0.34. In releases prior to this, one of the checks performed while determining the minimum footing size was that it has to be large enough to accommodate the development length required for flexural reinforcement without bends or hooks. That value was also overestimated to some extent. In the version you are running, this criterion is causing the footing to be larger than the 900 mm minimum you have specified. 
 This check has been removed in Build 9.2.0.34. This build gets automatically installed if you install the current version of STAAD.Pro. However, you can also download and install it independent of STAAD.Pro from the Bentley software downloads site.