This calculator will help you to calculate the Time Bandwidth Product ,with input value of Central wavelength (in nm), Half Width of Laser Spectrum (in nm) and Half Width of Laser Pulse (in fs).
$TBP$ = $\frac{c \triangle \lambda \tau}{\lambda_0^2}$
Pulse Shape, A; Center wavelength, $\lambda_0$; Speed of Light, C; Half Width of Laser Spectrum, $\triangle \lambda$;