The simplest way to tell them apart is by the alloying element: bronze is copper plus tin, while brass is copper plus zinc. That single difference cascades into everything else. Bronze is harder, more wear- and corrosion-resistant (especially in seawater), and often self-lubricating, which suits bearings and marine parts. Brass is more machinable, more workable, brighter in color, and cheaper, which suits fittings, decorative parts, and high-volume turned components. Choose bronze for strength, wear, and marine durability; choose brass for machinability, cost, and appearance.
This guide breaks down composition, properties, and typical uses so you can pick the right copper alloy. For the full range, see our materials catalog, and for the lead-free bronze used in plumbing, our guide to bismuth bronze.
Composition
Bronze is primarily copper and tin, typically around 88% copper and 12% tin, though it varies. Other elements such as phosphorus, silicon, aluminum, manganese, nickel, or zinc are added to create families like phosphor bronze, silicon bronze, aluminum bronze, and bearing bronze. Tin is what makes bronze harder than copper and gives it its dull, golden-brown color.
Brass is primarily copper and zinc, with copper usually between 55% and 95% and zinc making up the balance. Adjusting the zinc changes strength, color, and ductility, and small additions tune behavior: lead improves machinability (as in free-machining C36000), while tin improves corrosion resistance against dezincification (as in admiralty brass). More copper makes brass redder; more zinc makes it lighter and brighter.
Properties Compared
| Property | Bronze (Cu + Sn) | Brass (Cu + Zn) |
| Hardness | Harder | Softer |
| Machinability | Good | Better (best in leaded grades) |
| Corrosion resistance | Excellent, especially marine | Good (high-zinc prone to dezincification) |
| Friction | Low, often self-lubricating | Higher |
| Color | Dull gold to brown | Bright gold (varies with zinc) |
| Cost | Higher | Lower |
| Sound | Dull thud | Bright ring |
Neither alloy is magnetic. Bronze’s hardness, wear resistance, and saltwater performance make it the structural and tribological choice; brass’s workability, lower cost, antibacterial copper content, and attractive finish make it the choice for fittings, plumbing, and decorative work.
Typical Applications
Bronze suits parts that see wear, load, or seawater: bearings and bushings, marine fittings, ship propellers, gears, valve components, bells, and sculptures. Bearing bronzes are prized for low friction, and bismuth bronze serves lead-free plumbing.
Brass suits parts that are machined in volume or seen by the eye: plumbing fittings, valves, connectors, fasteners, tubing, instruments, and decorative hardware. Its excellent machinability makes it a favorite for screw-machine parts.
How to Choose
Pick bronze when you need hardness, wear resistance, low friction, or corrosion resistance in marine and harsh environments, and you can accept a higher cost. Pick brass when machinability, cost, and appearance matter most and the environment is less aggressive. When a part contacts drinking water, specify a lead-free grade such as bismuth bronze or a lead-free brass to meet regulations. When two candidates are close, the deciding factors are usually cost and machinability, where brass tends to win, versus durability and marine performance, where bronze wins.
We machine both alloy families through our CNC machining and CNC turning services. Request a quote and we will help you select the right copper alloy.
Frequently Asked Questions
What is the main difference between bronze and brass?
The alloying element. Bronze is copper and tin; brass is copper and zinc. That difference makes bronze harder and more corrosion- and wear-resistant, while brass is more machinable, cheaper, and brighter.
Which is stronger, bronze or brass?
Bronze is generally harder and more wear-resistant because of its tin content, and it performs better in marine environments. Brass is more ductile and workable, which is an advantage for forming and machining.
Which is better for marine use?
Bronze, because it resists saltwater corrosion better than most brasses. Many marine fittings, propellers, and submerged bearings are bronze. High-zinc brasses can suffer dezincification in seawater.
Which is easier to machine?
Brass, especially free-machining leaded grades like C36000. Its superior machinability and lower cost make it a common choice for high-volume turned and screw-machine parts.