6-pounder gun or 6-pdr, usually denotes a 57-millimetre (2.2 in) gun firing a projectile weighing approximately 6 pounds (2.7 kg).
Guns of this type include:
- QF 6 pounder Hotchkiss, a 57 mm naval gun of the 1880s
- QF 6 pounder 6 cwt Hotchkiss, a British 57 mm tank gun of 1917
- QF 6 pounder Nordenfelt, a 57 mm naval gun of the 1880s very similar to the Hotchkiss
- Ordnance QF 6 pounder, a British 57 mm anti-tank and tank gun of World War II
- QF 6 pounder 10 cwt gun, a British twin mount naval and coast defence gun 1937–1956.