The following are some calculator that will help you compute the diffraction limit size with input value of wavelength and numerical aperture

www.simtrum.com

$R_R$=$\frac{0.61 \lambda}{NA}$

$R_A$=$\frac{0.51 \lambda}{NA}$

Input
Wavelength, $\lambda$:
nm

Numerical Aperture, $NA$:


Output
Rayleigh Criterion, $R_R$:
nm

Abbe Criterion, $R_R$:
nm