Astudy of 428 endodontically treated 1″ permanent molar teeth of both jaws was performed to identify the variation in tooth length of Bangladeshi people. In this study, radiographic method, Ingle’s method was used and mathematical calculation as purposed by Messing was used to measure the length of the individual canal. The method involves measurement of the length in pre operative radiograph followed by clinical evaluation with diagnostic radiograph. The working length of each canal was finally calculated comparing both pre-operative and diagnostic radiograph. Study revealed that average length of upper 1″ molar is 20.62mm and for lower 1″ molar is 20.28mm; the range oflength for upper 1″ molar is 17.16mm – 25.33mm and for lower 16mm – 24mm.