A bronze bar is a bar of metal, refined through the Smithing skill by smelting copper ore and tin ore in a furnace together, granting 6.2 Smithing experience.
A bronze bar can be forged on an anvil to create bronze weapons and armour, granting 12.5 Smithing experience per bar used. A list of bronze items that can be smithed from bronze bars and the Smithing levels required can be found on the Smithing tables.
Assuming all materials are purchased on the Grand Exchange, the cost to produce a bronze bar is 114 coins. As a bronze bar is currently worth 254 coins, each bar represents a profit of 140 coins. If using Superheat Item along with a staff of fire, smelting a bronze bar produces a profit of -281 coins.