An adjustable table has a base, a telescopic tube assembly, two outside tabletop components and two inside tabletop components. The base has at least one leg and a mounting bracket. The telescopic tube assembly has a shaft, a central tube and two sliding tubes. The shaft is located over the mounting bracket. The central tube is mounted securely around the shaft. The sliding tubes are mounted slidably around the shaft. The outside tabletop components are mounted slidably on the mounting bracket and are slidably mounted respectively on the sliding tubes. The inside tabletop components are foldable and each has a first board mounted pivotally and slidably on one sliding tube and a second board connected pivotally to the first board. Each inside tabletop component independently folds and flips underneath the outside tabletop components abut each other or abut one of the inside tabletop components to shorten a total tabletop length.