Justification of the quasi one-dimensionality assumption in the analysis of fins of various shapes has been traditionally based on the criterion that fins have large slenderness ratios, i.e., large length and small thickness. This simplistic approach is based on a mere geometric consideration that obviates the implications of the two-dimensional heat paths in the axial and transversal directions that occurs in fins. Beginning with the formal differential formulation of the two-dimensional heat conduction equation for straight fins of uniform profile and the appropriate boundary conditions, the central objective of the present paper is to develop a systematic mathematical procedure that revolves around a new corrected quasi one-dimensional heat conduction equation that is more physically sound. The step-by-step mathematical development depends on two controlling parameters: (1) a thermo-geometric parameter, i.e., the transverse Biot number based on the half-thickness, and (2) a geometric parameter, i.e., the slenderness ratio. The computed two-dimensional heat transfer rates clearly demonstrate that the corrected quasi one-dimensional heat conduction equation captures the two-dimensional heat paths flawlessly and as a direct result is better than the standard quasi one-dimensional heat conduction equation. The discrepancy between the corrected quasi one-dimensional and the standard quasi one-dimensional heat transfer rates is of the order of 10%. research_article articles 2019-04-01 Corrected quasi one-dimensional heat conduction equation for the analysis of straight fins of uniform profile en https://link.springer.com/10.1007%2Fs00231-018-2485-1 https://scigraph.springernature.com/explorer/license/ false 2019-04 1023-1031 2019-04-11T13:24 Heat and Mass Transfer 0947-7411 1432-1181 dimensions_id pub.1107273082 Departamento de Ingeniería Térmica y de Fluidos, Universidad Carlos III de Madrid, Avda. Universidad 30, 28911, Leganés, Madrid, Spain Carlos III University of Madrid Springer Nature - SN SciGraph project 4 Pure Mathematics e1809004d62251c975fa41e5f7ba43f5fd4e640177e8b10e0c30e163e5600ef6 readcube_id Mathematical Sciences 55 Department of Mechanical Engineering, The University of Vermont, 55455, Burlington, VT, USA University of Vermont Campo Antonio doi 10.1007/s00231-018-2485-1 Antonio Acosta-Iborra