Run-off or runoff may refer to:
- Surface runoff, the flow of water, from rain, snow melt, or other sources, over land
- Runoff model (reservoir), a mathematical model describing the rainfall-runoff relations of a rainfall catchment area or watershed
- Runoff curve number, an empirical parameter used in hydrology
- Runoff voting or Two-round system, a voting system used to elect a single winner, whereby only two candidates from the first round continue to the second round
- Instant-runoff voting, an electoral system in which voters rank the candidates in order of preference
- RUNOFF, the first computer text formatting program, running on the CTSS operating system
- Runoff (program), the type-setting program on the Multics operating system
- Run-off area, an area on a racetrack for racer safety
- Bleed (printing), printing that goes beyond the edge of the sheet after trimming