The short answer: A typical military submarine weighs between 2,000 and 18,000 metric tons (about 4.4 to 39.7 million pounds), depending on its class.
Submarine weight by type
Submarine weight varies widely by purpose, from small research craft to enormous ballistic-missile boats. The table compares common categories.
| Submarine type (example) | Typical weight |
|---|---|
| Small research / tourist sub | A few tons to a few hundred tons |
| Diesel-electric attack submarine | Roughly 2,000 to 4,000 metric tons |
| Nuclear attack submarine | About 6,000 to 9,000 metric tons |
| Ballistic-missile submarine | Up to about 18,000 metric tons or more |
What affects submarine weight
- Submarine class. Attack, ballistic-missile, and research submarines differ enormously in size and weight.
- Power source. Nuclear submarines carry heavy reactors and tend to be larger than diesel-electric boats.
- Surfaced versus submerged. Submerged displacement is higher because the ballast tanks fill with water.
- Armament. Missile tubes and torpedoes add weight to combat submarines.
- Crew and supplies. Stores for long patrols add to the operating weight.
- How weight is measured. Submarines are usually described by displacement, which differs from a cargo ship's deadweight figure.
How submarine weight compares
A large ballistic-missile submarine at around 18,000 metric tons weighs roughly as much as 3,000 African elephants, or a mid-size cargo ship.
Frequently asked questions
How much does a submarine weigh?
A typical military submarine weighs between 2,000 and 18,000 metric tons, depending on its class. Small research submarines can weigh just a few tons.
What is the heaviest submarine ever built?
Soviet Typhoon-class ballistic-missile submarines were the largest, displacing roughly 48,000 metric tons submerged. They remain the heaviest submarines ever built.
Why does a submarine's weight change when it dives?
Submarines take on water in their ballast tanks to submerge, increasing their effective displacement. Surfaced and submerged displacement are therefore different figures.
