Small dislocation loops formed from self-interstitial atoms (SIAs) are commonly found in irradiated metals. These defects significantly influence the mechanical properties of the materials. Atomistic simulations are used to describe nanometric circular dislocation loops with Burger’s vectors 1/2a0<111>, a0<100>, and a0<110> in bcc tungsten. Particular attention is paid to the habit plane of the 1/2a0<111>loop. Two different embedded atom model (EAM) potentials are used. The energetics and geometry of the loops are studied as a function of their size.