J.M.W. Turner bequeathed about 300 oil paintings to the British nation.
Turner died in 1851 and left the contents of his studio to the nation as the Turner Bequest. The collection included nearly 300 oil paintings, along with roughly 30,000 sketches and watercolours, including hundreds of sketchbooks. Because sources commonly round the oil-painting total to 300, that is the standard quiz answer.
Turner wanted his major works preserved together in a dedicated gallery. His will specifically requested that Dido Building Carthage and Sun Rising Through Vapour be displayed between two works by Claude Lorrain, an artist he greatly admired. The planned gallery was not created as he envisioned.
Most of the bequest is now associated with Tate Britain’s Clore Gallery, while selected paintings remain at the National Gallery. The figures can vary slightly depending on whether unfinished works, studio pictures, and later attributions are counted, but 300 is the accepted rounded total.