A metric (more specifically, move count metric or turn metric) is a convention for counting moves. The same sequence of moves can have different move counts depending on the metric used.
Summary of different metrics
For more details, see the respective articles.
- HTM; Half Turn Metric (or Face Turn Metric): Any face turn of any angle counts as 1 turn.
- QTM; Quarter Turn Metric: Only quarter (90-degree) face turns count as 1 turn.
- STM; Slice Turn Metric: Any turn of any layer, by any angle, counts as 1 turn.
- QSTM; Quarter Slice Turn Metric: Only quarter turns of any layer, by any angle, counts as 1 turn.
- ATM; Axial Turn Metric: Any movement within the same axis counts as 1 turn.
- ETM; Execution Turn Metric: Any perceived movement counts as 1 turn.
- OBTM; Outer Block Turn Metric: The official metric of the WCA in which all non-slice moves on all twisty puzzles are considered 1 move and rotations are 0 moves
- BTM; Block Turn Metric: A metric for measuring movecounts on Bigcubes
Debate over metric in FMC
- (Speedsolving Forum) Move count metrics for big cubes - standards and preferences