Lambda value/ AFR correlation

[Brad Sheridan]

 Hi,
  I can't seem to remember off the top of my head what the relationship
between lambda and AFR is. Anybody know it? Also, I looked in the archives,
and saw a few different values for AFR at lambda = 1. One of them was
14.57:1, another(the one I'd always heard as being correct) was 14.7:1. The
NGK sensor data sheet I have shows 14.57:1. Anyone know the correct AFR at
lambda = 1?

Thanks,
Brad