Lightest and smallest robots: 34 models from 28 grams to 45 kilograms

A small robot is not just a toy. A lighter one is easier to transport, can sit on a desk or in a classroom, and will not hurt anyone if it falls. This roundup covers 34 models in the Robolupa catalogue: humanoids, quadrupeds, service, education and home robots weighing up to 20 kg, plus humanoids up to 125 cm tall. Weight is given for 189 of 343 models and height for 157, so the list leaves out robots whose manufacturer did not disclose these figures. For comparison, the median weight of a humanoid in the catalogue is 60.5 kg (74 models with data).

The spread is enormous. At the bottom is the Ozobot Evo: 28 grams, 3.35 cm, 175 USD. The cheapest, though, is the Enabot ROLA PetPal (0.525 kg) at 169 USD, or 579 PLN (≈ EUR 130) in a Polish shop. The light class also includes the home robots Casio Moflin (0.26 kg) and LOVOT 3.0 (4.6 kg). Among the typical education figures are the ROBOTIS OP3 (3.5 kg, 51 cm), the NAO (5.4 kg, 58 cm) and the prototype SigmaBan (7.5 kg, 70 cm). Three entries are desktop education arms: the myCobot 320 (3.36 kg), Dobot Magician (3.4 kg) and Kinova Gen3 Lite (5.4 kg). They do not walk, but they sit on the same list because the same transport and safety considerations apply to their weight.

The lightest quadrupeds are the education kits Petoi Bittle X (0.35 kg) and MangDang Mini Pupper 2 (0.45 kg). Among full-size quadrupeds the lightest is the Xiaomi CyberDog 2 (8.9 kg), followed by two models at 12 kg: the DEEP Robotics Lite3 and the Polish MAB Robotics Honey Badger 4.0 from MAB Robotics Sp. z o.o., which has the status of withdrawn in the catalogue. The best-known Unitree Go2 weighs 15 kg and starts at about 1,600 USD, and the wheeled Unitree Go2-W weighs 18 kg. Right at the 20 kg limit sits the new Unitree As2, available in a Polish shop for 53,900 PLN (≈ EUR 12,330). For comparison, the median weight of quadrupeds in the catalogue is 33.8 kg (15 models).

The small humanoids are the most interesting. The Noetix Bumi is 94 cm tall, weighs 12 kg and costs 1,402 USD, making it the cheapest humanoid in this roundup. The Booster K1 is 95 cm and 19.5 kg for 12,500 USD, and the LimX Dynamics TRON 1 84.5 cm and 20 kg. The Unitree R1 family is 123 cm tall and weighs 25 to 29 kg, at prices from 4,900 to 10,500 USD. Also within 125 cm are the Rainbow Robotics HUBO-2 (45 kg) and iCub (104 cm, 22 kg), while the Booster T1 weighs 30 kg. Of this group, 31 entries have the status "on sale" and 11 are available in Poland.

Who is it for? Schools, universities and student clubs without the space or budget for a full-size humanoid; see “Educational Robots for Schools and Universities” and educational robots. The Unitree R1 family is compared with larger models in “Unitree H1, G1, R1 and H2”. Remember that low weight usually means a small payload and short runtime. Note also that 34 entries are not 34 different products: Unitree accounts for 6 of them (the R1 in three variants, the Go2 in two, plus the As2).