I assume that you need precision although you post about resolution.
on that note

Steve wrote:
The main point is that RESOLUTION is NOT the same as PRECISION. Its "easy" to have 16 bits of resolution, much, much harder to have 16 bits of PRECISION.
To acquire a precision of the resolution you are looking for (sorry my math was wrong in my previois post) you can not make it by knowing how to design, you need "know-how". Of course you can start building and acquire that.
1) forget any idea of a board with less than 4 layers (go for 6).
2) forget any idea of trimpot calibration.
3) forget any idea of not having temperature compensation.
4) plan on many iterations before you get it right - THEN
5) plan on fixing the design when the customers report what is wrong.

Joseph wrote:
... do some other thing in signal conditioning ...
Unfortunately I have no experience with load cells so I am not sure what is feasible in your particular case

well, the scale I were involved with which were made to be as cheap as possible (basic model $99) did incur the expense of a chopper stabilized amplifier to meet the specs.

a scale is a funny thing, if they are off to one side the customer sue, if they are off to the other the mercant goes broke.

In the US any scale used for transactions must be certified by a government organization (W&M). I do not know how that is in India, but a transaction done with a scale that is off is, by definition, fradulent.

Erik