A cannonball’s weight depends on its type, historical period, and the artillery system it was designed for. Traditional solid iron cannonballs ranged from a few pounds for smaller guns to more than 40 pounds for some heavy naval guns. Their diameter also varied, so identifying a cannonball requires more than measuring its width.
Cannonball Size and Weight Chart
Historical cannonballs did not all share the same dimensions. The following chart uses a historical British round-shot reference to show how the weight of a solid iron ball relates to its diameter. Other artillery systems and periods used different specifications.
| Cannonball weight | Approx. diameter | Diameter in centimeters | Weight in kilograms |
|---|---|---|---|
| 3 lb | 2.77 in | 7.04 cm | 1.36 kg |
| 4 lb | 3.05 in | 7.75 cm | 1.81 kg |
| 6 lb | 3.49 in | 8.86 cm | 2.72 kg |
| 9 lb | 4.00 in | 10.16 cm | 4.08 kg |
| 12 lb | 4.40 in | 11.18 cm | 5.44 kg |
| 18 lb | 5.04 in | 12.80 cm | 8.16 kg |
| 24 lb | 5.55 in | 14.10 cm | 10.89 kg |
| 32 lb | 6.10 in | 15.49 cm | 14.51 kg |
| 42 lb | 6.68 in | 16.97 cm | 19.05 kg |
Note: Diameters come from the historical British round-shot reference. Metric weights are conversions from the nominal pound values. These are reference figures, not universal specifications for every historical cannonball.
The table shows how quickly a cannonball’s weight increases with its diameter. A 6-pound ball is roughly 3.5 inches wide, while a 32-pound ball measures about 6.1 inches across. Because a sphere’s volume increases with the cube of its diameter, a relatively small increase in width can produce a substantial increase in weight.
How Heavy Is a Cannonball by Pounder Class?
A cannonball’s weight class identifies the intended solid-shot weight for a particular artillery system. Smaller guns used lighter projectiles, while heavier naval and coastal guns could fire balls weighing several dozen pounds. The exact dimensions depended on the gun’s design and the standards used at the time.
Small cannonballs
Small solid shot weighing around 3 to 6 pounds was used with light artillery. In the British reference table, a 3-pound ball measures about 2.77 inches across, while a 6-pound ball measures about 3.49 inches.
These projectiles were much easier to handle than heavy naval shot, although the gun and its carriage still required substantial equipment and trained crews.
Medium-weight cannonballs
Projectiles weighing 9, 12, or 18 pounds were common classes of historical artillery shot. Their diameters in the British reference are approximately 4 inches, 4.4 inches, and 5.04 inches, respectively.
The name of a gun does not always tell you the exact weight of every projectile it fired. For example, the US Army‘s Civil War reference lists a 12-pounder howitzer with an 8.9-pound projectile. This demonstrates why the type of gun and ammunition must be identified before comparing historical specifications.
Heavy naval and coastal artillery shot
Larger guns could fire solid shot weighing 24, 32, or 42 pounds. In the historical British reference, a 42-pound ball is about 6.68 inches in diameter and weighs roughly 19 kilograms.
These dimensions provide a useful historical reference for understanding heavy artillery. They should not be used alone to identify an unknown object, since other ammunition types and artillery systems may have different dimensions.
How Big Is a Cannonball?
The diameter of a cannonball is the distance across its widest point through the center. For traditional British solid iron shot, diameters ranged from under 3 inches for smaller projectiles to nearly 7 inches for some heavy naval shot. Historical examples from other systems may fall outside this range.
Cannonball diameter versus cannon bore diameter
Cannonball diameter and cannon bore diameter are related, but they are not identical. Historical smoothbore guns generally required clearance between the projectile and the inside of the barrel. This clearance, known as windage, allowed the ball to fit into the bore.
A British historical reference lists a 12-pound solid shot diameter of approximately 4.40 inches and a bore diameter of about 4.62 inches for one standard gun pattern. A different design could use different dimensions.
This distinction matters when comparing a measured ball with a surviving cannon or historical gun specification. A ball that is smaller than the bore may be consistent with a particular artillery system, but size alone does not prove that it came from that gun.
How material and construction affect weight
Most traditional solid cannonballs were made from cast iron. Their weight depends on both their volume and the density of the material. For a solid sphere, a larger diameter generally means a greater mass, assuming the material density remains similar.
Hollow projectiles behave differently. Two artillery rounds with similar outer diameters can have very different weights because one contains solid metal while another has an internal cavity.
Why surviving cannonballs may differ from reference measurements
A historical reference table describes a particular ammunition standard, not every object recovered centuries later. Corrosion, attached material, incomplete remains, manufacturing differences, and incorrect historical identification can complicate measurements.
For this reason, a measured diameter should be treated as one piece of evidence. A museum catalogue, archaeological report, or documented historical comparison is more useful than a single measurement alone.
Cannonball Weight vs. Cannon Weight
A cannonball and the cannon that fires it have very different weights. The pounder designation refers to the intended class of solid shot, not the total weight of the gun.
The US Army’s Table 6: Standard Field Pieces Used During the Civil War provides a clear example. Its Model 1841-1844 bronze smoothbore 6-pounder gun weighed 884 pounds, while its listed projectile weighed 6.10 pounds. The carriage was listed separately at 900 pounds.
| Component | Historical example | Weight |
|---|---|---|
| Cannon | US Model 1841-1844 bronze 6-pounder gun | 884 lb |
| Solid projectile | Projectile listed for that gun | 6.10 lb |
| Carriage | Artillery carriage | 900 lb |
These figures describe one historical weapon and its equipment, not a universal cannon weight. Larger guns, naval artillery, siege weapons, and different materials produced substantially different totals.
If your search is for how much does a cannon weigh, look for the specific gun model and distinguish the barrel or gun itself from the carriage and any transport equipment. If your question concerns the projectile, use the gun’s ammunition specifications instead.
Solid Cannonballs vs. Hollow Artillery Shells
Not every spherical artillery projectile was a solid cannonball. Historical artillery also used hollow rounds designed to carry explosive charges or smaller projectiles. The distinction matters because outer diameter alone does not reveal the projectile’s construction or actual weight.
The US National Park Service‘s Fort Scott National Historic Site describes several types of ammunition used with a 6-pound field gun, including solid shot, spherical case shot, and canister.
Solid shot
Solid shot is a solid projectile, historically often made from iron. Its mass is determined mainly by its size and material. Solid shot was used to strike targets through impact and could damage walls, buildings, fortifications, and other structures.
Spherical case shot and explosive shells
Spherical case shot was hollow and contained smaller iron balls and a bursting charge. Its internal construction differed from that of a solid ball, even when its external dimensions were similar. Other artillery shells also used hollow bodies to accommodate a bursting charge.
A suspected shell must never be assumed safe because it is old, rusty, or appears to be a solid sphere. An object may be corroded or damaged in ways that conceal its internal construction.
Why projectile type matters
When comparing historical weights, make sure the source refers to the same type of ammunition. A solid-shot weight table cannot automatically be applied to a hollow shell, case shot, canister, or other projectile.
For a historical identification, the strongest comparison uses the documented gun model, ammunition type, diameter, and reliable archaeological or museum records together.
Can You Identify a Cannonball While Metal Detecting?
Metal detecting can locate buried metal objects, but a strong iron signal does not establish that the target is a cannonball. Large pieces of scrap iron, tools, machinery fragments, and other metal objects may produce similar signals.
What a metal detector can and cannot tell you
A detector may help establish that a metal target is present and provide an approximate location. Its signal does not reliably establish the object’s age, exact weight, historical origin, or whether it contains explosive material.
Use detector readings as preliminary information, not as proof of identity. If you suspect a historical artillery projectile, do not continue excavating simply to confirm its size or shape.
Why size and appearance alone cannot confirm authenticity
A round, heavily corroded object may resemble an old cannonball without actually being one. Conversely, a genuine historical projectile may have an irregular surface because of corrosion or other damage.
Reliable identification can require historical documentation, archaeological context, professional examination, and appropriate conservation expertise. Do not attempt to prove authenticity by cutting, drilling, striking, or aggressively cleaning a suspected projectile.
What to do if you discover a suspected cannonball
Stop digging and do not touch or move the object. An old artillery projectile may contain explosive material, and its appearance cannot establish that it is safe.
- Stop excavation and leave the object undisturbed.
- Move away from the immediate area without approaching it for a closer look.
- Keep other people away from the location.
- Contact local law enforcement or the appropriate bomb disposal or explosive ordnance authority and follow their instructions.
- Do not transport the object to a museum, home, vehicle, or police station yourself.
The National Park Service has documented discoveries of historic unexploded ordnance and provides a useful reminder that old military objects can present hazards.
Historical preservation can wait until qualified authorities determine that the object is safe.
FAQs About Cannon ball Size and Weight
1. How much does a typical cannonball weigh?
There is no single typical weight for all cannonballs. Historical solid shot ranged from a few pounds for smaller artillery to 42 pounds or more for some heavy guns. The exact weight depends on the artillery system, projectile type, and historical period. A reference table for a specific gun system is more reliable than a universal estimate.
2. How much does a 12-pound cannonball weigh?
A nominal 12-pound solid shot was intended to weigh about 12 pounds, or 5.44 kilograms. In the historical British reference, this ball measures approximately 4.40 inches in diameter. Actual historical ammunition and specifications from other systems can differ, so the designation should not be treated as an exact measurement for every surviving object.
3. How big is an 18-pound cannonball?
In the historical British round-shot reference, an 18-pound solid iron cannonball measures about 5.04 inches in diameter, or 12.80 centimeters. Other artillery designs may have different dimensions. The figure is most useful when comparing an object against the same historical ammunition system rather than using it as a universal identification standard.
4. How much does a cannon weigh compared with its cannonball?
The gun itself weighs far more than the projectile it fires. For example, a US Civil War-era bronze 6-pounder gun is listed at 884 pounds, compared with a 6.10-pound projectile. Its carriage weighed another 900 pounds. These are separate components, so historical records should be checked to determine whether a stated cannon weight includes its carriage.
5. Were all historical cannonballs made of iron?
No. Historical artillery used different materials depending on the period, weapon, and intended use. Stone projectiles were used in earlier artillery, while cast iron became common for many later solid-shot applications. The material affects both weight and durability, so an iron-shot reference should not automatically be applied to a stone projectile.
6. Can you safely pick up an old cannonball found while metal detecting?
No suspected artillery projectile should be picked up or moved to determine whether it is safe. Some historical rounds may contain explosive material, and corrosion can conceal hazards. Leave the object undisturbed, move away, keep others clear, and contact the appropriate authorities. Do not clean, strike, transport, or attempt to open it.
Choosing the Right Historical Reference for a Cannonball
If you are researching an old cannonball, begin with a documented reference for the relevant artillery system and historical period. Compare the recorded projectile type and diameter, and distinguish solid-shot specifications from those for hollow ammunition.
For metal detecting, the safest and most reliable decision is to leave any suspected artillery projectile undisturbed and seek qualified assistance. For historical research, use museum collections, archaeological reports, and military history references rather than relying on appearance alone.
