how do i measure force/weight in newton using FSR connected with arduino uno and a 16*2 LCD. i have heard everywhere it is not very accurate but still i want the way. so kindly help ASAP
You can't measure Newtons force/weight using an FSR, because the response is highly nonlinear and not very repeatable.
You can usually distinguish between "some weight" and "more weight".
Why don't you try?
Put a range of known masses on it and see if you can reliably distinguish between them.
If "everywhere" says it can't be done, then "still i want the way" might not be a reasonable expectation.
This tutorial at adafruit might help. It shows the non-linearity of the FSR they used: only looks linear because it's a log:log graph.