A laptop mostly weighs between 2 and 4 kilos . the weight of a bag containing a laptop , accessories such as a mouse and external keyboard, papers and a wallet can quickly add up to 4 to 6 kilos.
A backpack weighing this much has significant advantages over ‘ordinary ‘ laptop bags with a shoulder strap. Carrying it takes less energy, results in better posture and distributes muscle tension more symmetrically between the left and right sides of the body.
But whether you use a backpack or a shoulder bag , health experts recommend carrying a bag weighing 4 to 6 kilos no farther than 90 meters (Mital et al.,1993). For longer distances, they recommend using a trolley in order to take the strain off of the boby, particularly the back.