The free floor planner and home design tool from RoomSketcher makes it easy to draw out and plan your room layouts, as well as get a more visual idea of how things could fit.
Floor Planner offers a useful tool (the basic option is free) to create new floor plans and room layouts.
An easy-to-use online tool that will help you plan out the space you have available.
SketchUp is a 3D room planner with free and paid versions. Though not beginner-friendly, it offers free tutorials and is useful for space planning.