An interactive web-based tool has been developed at Oak Ridge National Laboratory (ORNL) to guide the end-user sample preparation for neutron imaging experiments. The tool is capable of estimating transmission through the sample using the cold neutron spectrum at the High Flux Isotope (HFIR) CG-1D imaging beamline. It can also predict the position and height of the resonance peaks at the Spallation Neutron Source (SNS) SNAP beamline when performing neutron resonance imaging with neutron energies higher than 1 eV. This tool provides robust and user-friendly sample input and utilizes measured/simulated beam spectrum at corresponding beamlines for accurate transmission/attenuation calculations. By using this tool, users who are interested in neutron imaging can test their ideas promptly and can better prepare samples for their experiments.