The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Nikon 18-55mm F3.5-5.6G VR and the Sigma 17-50mm F2.8 EX DC OS HSM for their suitability to various photography scenarios:
Size and Weight Comparison
Size of a lens is an important deciding factor when comparing two lenses.Sigma 17-50mm F2.8 EX DC OS HSM is the longer of the two lenses at 92mm. The Nikon 18-55mm F3.5-5.6G VR with a length of 63mm is 29mm shorter. Besides being longer, the Sigma 17-50mm F2.8 EX DC OS HSM also has a larger diameter of 84mm compared to Nikon 18-55mm F3.5-5.6G VR's 65mm diameter.
Weight of a lens is as important as its external dimensions, especially if you are planning to hand hold your camera and lens combination for longer periods. Nikon 18-55mm F3.5-5.6G VR weighs 205g, which means it is 360g (63%) lighter than the Sigma 17-50mm F2.8 EX DC OS HSM which has a weight of 565g.
Below you can find the dimension and weight table of the 'Standard Zoom Lenses in Nikon F (DX) Mount for size comparison purposes.
Standard Zoom Lenses in Nikon F (DX) Mount for Size Comparison
Lens Mounts
Both Nikon 18-55mm F3.5-5.6G VR and Sigma 17-50mm F2.8 EX DC OS HSM has the same Nikon F (DX) lens mount. Some of the latest released cameras that are compatible with the Nikon F (DX) lenses are Nikon D3500, Nikon D7500 and Nikon D5600.
Nikon 18-55mm F3.5-5.6G VR is also available in Nikon F (DX) mount.
Sigma 17-50mm F2.8 EX DC OS HSM is also available in Canon EF , Pentax KAF3, Sony Alpha and Sigma SA mounts.
Focal Range
Nikon 18-55mm F3.5-5.6G VR has a focal range of 18-55mm and 3.1X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 27-82.5mm when used on a APS-C / DX format camera. Sigma 17-50mm F2.8 EX DC OS HSM has a focal range of 17-50mm and 2.9X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 25.5-75mm when used on a APS-C / DX format camera.