The 30-pounder long gun was a large piece of artillery mounted on French warships of the Age of Sail.

They were the heaviest component of the unified system standardised on the 30-pounder calibre, replacing both the 36-pounder long guns in their usages, and even some 24-pounders.

Installed on the lower deck of the larger warships from the 1820s, the 30-pounder long gun was the largest caliber used in the late Navy of the Age of the Sail, used on the ships defined by the Commission de Paris.

The flagship Bretagne was an exception to this rule, retaining the older 36-pounder long gun as to maximise the weight of her broadside.

The differences in weight were obtained by fielding a large 30-pounder long gun, a shorter 30-pounder with a thinner barrel, and a 30-pounder carronade.