The Titanic’s maximum speed was about 23 knots.
That figure is the standard specification for the liner’s top speed, equivalent to roughly 43 kilometres per hour or 26 miles per hour. Titanic’s normal service speed was about 21 knots, so its maximum and cruising speeds are not the same figure.
Titanic’s propulsion combined two four-cylinder, triple-expansion reciprocating steam engines with a centrally located low-pressure Parsons steam turbine. The reciprocating engines drove the two outer propellers, while the turbine drove the smaller centre propeller. Steam came from 29 coal-fired boilers and produced roughly 46,000 horsepower.
Some historical accounts give a more precise estimated or trial figure of approximately 23¼ knots. That extra quarter-knot reflects the uncertainty of early speed measurements and the difference between a rounded published specification and a particular measured run. For a general-trivia question, 23 knots is the accepted canonical answer. The ship was not travelling at its maximum when it struck the iceberg; contemporary reconstructions place its speed at roughly 22 knots.