Infrared thermography is a useful tool in visualizing and quantifying spatial distribution in radiant heat of incandescent heat lamps. Radial temperature profiles of six commercially available heat lamps (100W to 250W) were comparatively characterized. Heat lamps with the same power output do not necessarily produce the same temperature profiles on the heated surface because the shape of the temperature profiles was shown to be greatly affected by the lamp lens prescription. At a lamp height of 45.7 cm (18 in.), the net usable area (NUA) for the piglets was 0.102, 0.155, 0.146, 0.275, 0.139 and 0.113 m2 (1.10, 1.67, 1.57, 2.96, 1.50, and 1.22 ft2), respectively, for 100W Retrolite (100CZ20), 125W Hogslat (125HOG), 125W SLI Lighting (125SLI), 175W Retrolite (175CZ20), 175W Phillips (175PLP), and 250W SLI Lighting (250SLI). The 175CZ20 had the largest NUA and was the most efficient lamp on the basis of NUA per rated Watt. Although the 250SLI had the largest lamp heated area, it and the 175PLP were the least efficient lamps due to the large hotspots they produced. Lamp height affects the size of heated area, hotspot area and NUA for most of the lamps tested. These results suggest that in a commercial swine farrowing system, the 175CZ20 has the most potential among the incandescent heat lamps tested for meeting the thermal needs of the piglets and improving energy efficiency of the localized supplemental heating.