The RPG-40 (Russian: ручная противотанковая граната образца 1940 года, romanized: Ruchnaya Protivotankovaya Granata Obraztsa 1940 Goda, lit. 'Hand anti-tank grenade model 1940') was an anti-tank hand grenade developed by the Soviet Union in 1940.

The RPG-40 is a blast anti-tank grenade, with a detonator fitted into a recess in the head of the grenade. Its stabilized in flight by a cloth ribbon which unfolds after being thrown.

Upon contact, 760 grams (1.68 lb) of explosives contained within it were detonated and produced a blast effect. This enabled about 20–25 mm (0.79–0.98 in) of armour to be penetrated and caused secondary damage, such as spalling, on contact with thicker armour.

Due to its heavy weight, the grenade could only be thrown at very short ranges, around 20–25 metres (22–27 yd) and behind protected positions, due to the blast and secondary fragmentation effect. According to Jane's, the grenade had an effective fragmentation radius of 20 m (22 yd).

It was also used against enemy defensive positions such as bunkers, machine gun nests, and pillboxes.

The RPG-40 was distributed to Red Army units in 1940, a year before the Great Patriotic War.

In July 1941, Main Artillery Directorate issued an order to begin mass production of these grenades as soon as possible. The production was organized by engineer S. Novikov.

It was effective against lightly armoured vehicles such as the Panzer I and Panzer II, but quickly became obsolete once the Germans started deploying heavier and better armoured tanks.