This master thesis presents the work done to measure and compare power efficiency of Bluetooth Low Energy technology versions is presented. More specifically, comparisons between different BLE core specification versions are made with regards to power consumption in relation to throughput. A brief history of Bluetooth Low Energy is presented, as well as the main improvements and differences between core specification versions. Measurements were performed with a single pair of devices, which had their connection parameters tuned in line with BLE version they were targeting. Power consumption was measured with different parameters, with read, write, notify and write without response BLE operations. As expected, results revealed that newer BLE versions offer higher throughput, as well as the fact that average power consumption is independent from the amount of data transmitted. Interestingly enough, with each BLE version, power consumption per transmitted amount of data is decreasing, even when the throughput is increased. It was also discovered that total energy needed to transmit some amount of data is constant when changing the throughput in a single core specification version. The findings in this thesis prove that there is no reason not to switch to developing and using devices that use Bluetooth Low Energy 5, as BLE 5 brings higher throughput, extended range and better coexistence while consuming the same or lower amount of energy for transmissions. Ta magistrska naloga predstavlja opravljeno delo, potrebno za meritve in primerjavo energetske učinkovitosti tehnologije Bluetooth Low Energy (BLE). Predstavljene so primerjave porabe električne energije glede na preto-čnost med različnimi verzijami standarda BLE. Predstavljena je kratka zgodovina tehnologije Bluetooth Low Energy, kot tudi glavne izboljšave in razlike med verzijami specifikacij tehnologije. Meritve smo opravili z enim parom naprav, kateri sta imeli parametre nastavljene glede na različico BLE, na kateri je test temeljil. Porabo energije smo merili z različnimi parametri, pri branju, pisanju, obveščanju in pisanju brez odziva. Po pričakovanjih so rezultati pokazali, da novejše verzije BLE ponujajo večjo pretočnost, pa tudi dejstvo, da je povprečna poraba energije neodvisna od količine poslanih podatkov. Zanimivo je, da se z vsako novo različico BLE poraba energije na preneseno količino podatkov zmanjša, tudi če se poveča pretočnost. Ugotovili smo tudi, da je energija, potrebna za prenos določene količine podatkov, konstantna pri spreminjanju pretočnosti pri določeni različici specifikacije. Ugotovitve v tej diplomski nalogi dokazujejo da ni razloga, da ne bi prešli na razvoj in uporabo naprav, ki uporabljajo tehnologijo Bluetooth Low Energy 5, saj prinaša večjo pretočnost, večji doseg in boljše sožitje z drugimi brezžičnimi tehnologijami, hkrati pa porabi isto ali manjšo količino energije za prenos podatkov.