Eyeballing it, it looks like Uranus is the closest planet to Neptune today, and will be for quite a while.
Remember, though, that planets orbit at different speeds. The planets are moving counterclockwise in this picture, and Uranus is getting farther away from Neptune every day. Sometimes Uranus and Neptune are on opposite sides of the Sun, with all the inner planets between them.
For example, on 4th of March 2020, Earth was closer to Mercury than Venus.
Ilgiardino.wiki
This web site has a diagramatic view which will not answer your question, and a “To Scale View” which will answer it.
Planets of our Solar System
Eyeballing it, it looks like Uranus is the closest planet to Neptune today, and will be for quite a while.
Remember, though, that planets orbit at different speeds. The planets are moving counterclockwise in this picture, and Uranus is getting farther away from Neptune every day. Sometimes Uranus and Neptune are on opposite sides of the Sun, with all the inner planets between them.
For example, on 4th of March 2020, Earth was closer to Mercury than Venus.