LTR or similar may refer to:
Measurement Ltr. (for 'litre' or 'liter'), a unit of volume Letter (paper size)
Science and technology Learning to rank, ordering data with machine learning Left-to-right mark, a bidirectional control character Load task register, a machine-code instruction Logic Trunked Radio, a two-way radio system Long terminal repeat, a DNA sequence
Other uses Left to right, a directionality of writing systems
Little River railway station, Australia London Turkish Radio, an Internet radio station
See also Left to Right, a song by Kitty Wells Left to Right (short story), a short story by Isaac Asimov