What was the heaviest bomb ever dropped?

Short answer

The Grand Slam, at 22,000 lb (10,000 kg), was the largest and most powerful conventional, non-nuclear aerial bomb used by either side during the war, and remained the heaviest until the T-12 Cloudmaker was deployed in 1949. It was designed by Barnes Wallis.

Published: November 5, 2026 · Updated: November 5, 2026 · Edited by Above Ten Thousand · Editorial policy

What was the heaviest bomb ever dropped?

Lancaster B Mk I R5852 of No. 83 Squadron in flight over Lincolnshire, June 1942

A ten-tonne bomb

The Grand Slam weighed 22,000 lb (10,000 kg) and was the largest and most powerful conventional, non-nuclear aerial bomb used by either side during the war. It was designed by Barnes Wallis. The explosive charge was 9,500 lb (4,300 kg), giving a charge-to-weight ratio of 43 percent. It measured 26 ft 6 in (8.08 m) long and 3 ft 10 in (1.17 m) in diameter.

A special Lancaster to carry it

Standard Avro Lancasters could not carry the bomb, so Avro built 32 Lancaster B.Mk 1 (Special) aircraft with more powerful variants of the Merlin engine and reinforced landing gear.

Operational use and succession

Between 14 March and 19 April 1945, 42 Grand Slams were dropped on Germany. It remained the heaviest bomb until the T-12 Cloudmaker was deployed in 1949.