Well, that's not much of a payload, but remember - a rocket has to propel itself *and* any payload to orbit... So - to that end, here's the smallest rocket ever to *get* to orbit:
The smallest orbital rocket is SS-520-5, measuring 9.54 m (31 ft 3.5 in) tall and 0.52 m (1 ft 8 in) in diameter and weighs 2,600 kg (5,732 lb), achieved by Japan Aerospace Exploration Agency (Japan) in Uchinoura Space Center, Kagoshima Prefecture, Japan, launched on 3 February 2018.This tiny rocket was launched at 2:03 p.m. (JST; 05:03 UTC) on 3 February 2018 from the Japanese Space Agency's Uchinoura Space Center in Kagoshima Prefecture, Japan. It carried a 3-kg (2 lb 8.7 oz) CubeSat called TRICOM-1R (which was renamed "Tasuki" once it was in orbit).The SS-520 is the three-stage "big-brother" of the S-520 sounding rocket (a sounding rocket is a sub-orbital rocket designed to carry scientific instruments for atmospheric research). It has less than 1% of the mass of the Soyuz rockets used to launch astronauts to the ISS, and is dwarfed even by small rockets like the Rocket Labs Electron (which has a mass of around 10 tonnes).SS-520-5 was JAXA's second attempt to use this system to place a payload in orbit. The previous attempt (SS-520-4) failed on 14 January 2017, destroying the first version of the TRICOM-1 satellite in the process.