60mm mortars are the most common caliber for an infantry support mortar that reasonably can be carried by well-conditioned troops, rather than requiring vehicle transport. Some smaller calibers, such as 50mm by Commonwealth countries and the WWII Japanese Type 89, have been used. The formal Japanese designation for their weapon, however, was "grenade launcher", and, with modern weapons, there is a blurring of effects between 40mm grenade launchers and 60mm mortars. While mortars are usually high-angle indirect fire weapons, used by dropping projectiles into the muzzle until they hit the firing pin, many mortars also have a trigger-fired, direct fire mode making them even more like grenade launchers. Still, a mortar does not replace a grenade launcher and a grenade launcher does not replace a mortar.
For a time after WWII, light mortars were out of fashion, as they were believed to lack range and lethality. Light infantry and special operations units, such as paratroops, British Special Air Service and U.S. Army Rangers, however, insisted on having them. In current U.S. Army practice, there are distinct and complementary roles for the 60mm mortars, 120mm mortars at battalion level, .50 caliber M2 machine guns and MK 19 40mm automatic grenade launchers, and 105mm and 155mm howitzers. 
With the resurgence of the weapon class, research is going into reducing their weight, along with that of 81mm mortars, to improve flexibility and possibly provide more effective projectiles. Using a more advanced high temperature nickel superalloy (Inconel 718) heat-resistant mortar tube, the rate of fire and the tube lifetime were increased; use of aluminium, titanium and composites in the bipod and baseplate further reduced weight.
The U.S. Army M224 60mm Lightweight Company Mortar System (LWCMS) is representative of current production mortars of its class  For carrying, the weapon is broken into:
- M225 Barrel Assembly: Weight 14.4 lbs., Length 40 in.
- M170 Bipod Assembly: Weight 15.2 lbs., Length 40 in.
- M7 Mortar Baseplate: Weight 14.4 lbs.
- M8 Hand Held Mode Baseplate: Weight 3.6 lbs.
- M64A1 Sight Unit: Weight 2.5 lbs.
The minimum range, for indirect fire, is 70 meters, and the maximum is 3500 meters. It can be fired at a rate of 30 rounds in the first minute and 20 rounds per miniute in continuing fire.