A Bachelor of Science (Latin Baccalaureus Scientiae, B.S., BS, B.Sc., BSc, or B.Sc; or, less commonly, S.B., SB, or Sc.B., from the equivalent Latin Scientiae Baccalaureus)  is an undergraduate academic degree awarded for completed courses that generally last three to five years, or a person holding such a degree. 
Whether a student of a particular subject is awarded a Bachelor of Science degree or a Bachelor of Arts degree can vary between universities. For example, an economics degree may be given as a Bachelor of Arts (BA) by one university but as a BS by another, and some universities offer the choice of either.  Some liberal arts colleges in the United States offer only the BA, even in the natural sciences,  while some universities offer only the BS even in non-science fields.  Georgetown University's School of Foreign Service awards Bachelor of Science in Foreign Service degrees to all of its undergraduates, although many major in humanities-oriented fields such as international history and culture and politics.
The London School of Economics offers BSc degrees in practically all subject areas, even those normally associated with arts degrees, while the Oxbridge universities almost exclusively award arts qualifications. In both instances, there are historical and traditional reasons. Northwestern University's School of Communication grants BSc degrees in all of its programs of study, including theater, dance, and radio/television/film. University of California, Berkeley grants BS degree in Environmental Economics and Policy in College of Natural Resources (CNR), BS degree in Business Administration in Haas School of Business and BA degree in Environmental Economics and Policy in College of Letters and Science (L&S). Cornell University offers a BS degree in Computer Science from its College of Engineering and a BA degree in Computer Science from its College of Arts and Sciences.
The first university to admit a student to the degree of Bachelor of Science was the University of London in 1860.  Prior to this, science subjects were included in the BA bracket, notably in the cases of mathematics, physics, physiology and botany.
B.Sc degree  is divided in two categories: Core B.Sc degree and Professional B.Sc degree.
The core B.Sc degree includes the degree in following specifications:
- B.Sc. (PCM)
- B.Sc. (Physics)
- B.Sc. (Chemistry)
- B.Sc. (Maths)
- B.Sc. (Zoology)
- B.Sc. (Statistics)
- B.Sc. (Botany)
- B.Sc. (Home Science)
The professional B.Sc degree includes the degree in following specifications:
- B.Sc .(Agriculture)
- B.Sc. (Animation)
- B.Sc. (Aquaculture)
- B.Sc. (Aviation)
- B.Sc. (Biochemistry)
- B.Sc. (Bioinformatics)
- B.Sc. (Computer Science)
- B.Sc. (Dietetics)
- B.Sc. (Electronic)
- B.Sc. (Fashion Technology)
- B.Sc. (Food Technology)
- B.Sc. (Forensic Science)
- B.Sc. (Forestry)
- B.Sc. (Medical Technology)
- B.Sc. (Microbiology)
- B.Sc. (Multimedia)
- B.Sc. (Nautical Science)
- B.Sc. (Nursing)
- B.Sc. (Nutrition)
- B.Sc. (Physiotherapy)
- B.Sc. (Psychology)
- B.Sc. (Genetics)
- B.Sc. (Information Technology)
- B.Sc. (Interior Design)
In Chile, the completion of a university program leads to an academic degree as well as a professional title. The academic degree equivalent to Bachelor of Science is " Licenciado en Ciencias ", which can be obtained as a result of completing a 4–6 year program.  However, in most cases, 4 year programs will grant a Bachelor of Applied Science (Spanish: "Licenciatura en Ciencias Aplicadas") degree, while other 4 year programs will not grant to an academic degree.
In Argentina most university degrees are given as a license in a field or discipline. Degrees are specific to a field and are usually 5–6 year programs including a 1 to 1.5-year mandatory internship, which starts after students have completed 70-80% of the courses required. Degrees are term licenses in the field of study or profession. i.e., biology, nutrition, physical therapy or kinesiology, etc.
Australia, New Zealand, and South Africa
In Australia, the BSc is generally a three-four year degree. An honours year or a Master of Science (MSc) is required to progress on to the Doctor of Philosophy (PhD). In New Zealand, in some cases, the honours degree comprises an additional postgraduate qualification. In other cases, students with strong performance in their second or third year, are invited to extend their degree to an additional year, with a focus on research, granting access to doctoral programs. In South Africa, the BSc is taken over three years, while the postgraduate BSc (Hons) entails an additional year of study. Admission to the honours degree is on the basis of a sufficiently high average in the BSc major; an honours degree is required for MSc level study, and admission to a doctorate is via the MSc.
Britain and Ireland
Commonly in British Commonwealth countries and Ireland graduands are admitted to the degree of Bachelor of Science after having completed a programme in one or more of the sciences. These programmes may take different lengths of time to complete.
A Bachelor of Science receives the designation BSc or BS for a major/pass degree and BSc (Hons) or BS (Hons) for an honours degree. In England, Wales and Northern Ireland an honours degree is typically completed over a three-year period, though there are a few intensified two-year courses (with less vacation time). Bachelor's degrees (without honours) were typically completed in two years for most of the twentieth century. In Scotland, where access to university is possible after one less year of secondary education, degree courses have a foundation year (simply known as the First year) making the total course length four years. In Ireland, the former BS. was changed to BSc (Hons) which is awarded after four years. The BSc (Ord) is awarded after three years.  Formerly at the University of Oxford, the degree of BSc was a postgraduate degree; this former degree, still actively granted, has since been renamed MSc.
In Canada, Mexico & the United States, It is generally a four-year  undergraduate degree typically used in engineering, computer science, mathematics, economics, and the natural sciences. Many universities are starting to offer accelerated 3-year BS programs.  
Many universities in Europe are changing their systems into the BA/MA system, and in doing so also offering the full equivalent of a BSc or MSc See Bologna Process.
Universities in the Czech Republic are changing their systems into the Bachelor of Science / Master of Science system, and in doing so also offering the full equivalent of a BSc (Bc.) or MSc (Mgr./Ing.).
In Germany, there are two kinds of universities: Universitäten and Fachhochschulen (which are also called University of Applied Sciences). Universitäten and Fachhochschulen – both also called Hochschulen - are legally equal, but Fachhochschulen have the reputation of being more related to practice and have no legal right to offer PhD programmes.
The BSc in Germany is equivalent to the BSc(Hons) in the United Kingdom. Many universities in German-speaking countries are changing their systems to the BA/MA system, and in doing so also offering the full equivalent of a BSc.
In Germany the BA normally lasts between three and four years (six to eight semesters) and between 180 and 240 ECTS must be earned.
In Brazil, a Bachelor of Science degree is an undergraduate academic degree and is equivalent to a BSc (Hons). Could takes from 4 to 6 years (8 to 12 periods), is also more specific and could be applied for Scientific Arts courses (like Engineering, Maths, Physics, etc.), somewhat is called Human Art courses in Brazil (like History, Portuguese and Literature and Lawyer studies for example) as well as for Health Arts (like Medicine, Nursery, Zootechnique, Veterinary and Biology for example). To be able to start the bachelor's degree in Brazil the candidate must to prove proficient in different disciplines and have at least the accumulated Preliminary, Medium and High School degrees accomplished with the minimum merit of 60% to 70% of the degrees and a correspondent study period that can vary from 10 to 12 years minimum. The Bachelor of Science courses in Brazilian Universities normally have the first 1 to 2 years (first 2 to 4 periods) of basics fundamental disciplines (like for example Calculus I, II, III and IV for some engineering courses, Geometry basics and advanced, Analytical Laboratories experiments in Mechanics, Optics, Magnetism, etc.) and the last 2 to 3 years disciplines more related to the professional fields of that Bachelor of Science (for example Units Operations, Thermodynamics, Chemical Reactors, Industrial Processes Kinetics for Chemical Engineering for example). Some disciplines are prerequisite to others and in some universities, the student is not allowed to course any discipline of the entire next period if he was unsuccessful in just one prerequisite discipline of the present period. Usually, the Bachelor of Sciences courses demand a one-year mandatory probation period by the end of the course (internship in the specific professional area, like a training period), followed by relatively elaborate written and oral evaluations. To get the certification as BSc most Universities require that the students achieve the accomplishment of 60% to 70% in all the "obligatory disciplines", plus the supervisioned and approved training period (like a supervisioned internship period), the final thesis of the course and in some BSc. the final exam test. The final exam also is required so far. To be able to be a Professor, a Bachelor of Sciences is obligate to get a Licenciature degree, which lasts on top of the periods already studied until getting the BSc. (Hons), more 2 to 3 periods (1 to 1.5 years). With a master's degree (MSc) is also possible, which takes 3 to 5 periods more (1.5 to 2.5 years more).
Typical completion period
Australia, Austria, Barbados, Belgium, Belize, Bosnia and Herzegovina, Cameroon, Canada (especially Quebec), Cote d'Ivoire, Croatia (mostly three years, sometimes four), Czech Republic (mostly three years, sometimes four), Denmark, England (three or four years with a one-year placement in industry), Estonia, Finland, France, Germany (mostly three years, but can be up to four years), Hungary, Iceland, India (three years BSc in pure sciences excluding engineering and medicine and four years engineering program " Bachelor of Engineering "), Ireland (Ordinary), Israel (for most subjects), Italy, Jamaica (three or four years), Latvia (three or four years), Lebanon (three or four years, five years for Bachelor of Engineering), Malaysia, New Zealand, Netherlands (three years for research universities, four years for universities of applied sciences), Northern Ireland, Norway, Poland, Portugal, Romania, Scotland (Ordinary), Singapore (honours degree takes 4 years), Slovakia, Slovenia, South Africa (honours degree takes 4 years), Sweden, Switzerland, Trinidad and Tobago, Uganda (mostly three years, sometimes four), United Arab Emirates, Wales and Zimbabwe.
Armenia (four or five years), Albania (four or five years), Afghanistan, Azerbaijan (four or five years), Australia (honours degree), Bangladesh (four or five years), Bahrain, Belarus, Belize, Brazil (four to five years), Brunei (three or four years), Bosnia, Bulgaria, Canada (except Quebec), China, Cyprus, Egypt (four or five years), Ethiopia (engineering, five years), Finland (engineering, practice in industry not included), Georgia, Dominican Republic, Guatemala, Ghana (three or four years), Greece (four or five years), Haiti (three or four years), Hong Kong (starting from 2012, three years originally), India (four-year BS, Engineering), Indonesia, Iran (four or five years), Iran, Iraq, Ireland (Honours Degree), Israel, Japan, Jordan (four to five years), Kazakhstan, Kuwait, Lithuania, Libya, Malawi (four or five years), Malta, Macedonia (three, four or five years), Montenegro (three or four years), Mexico, Myanmar, Nepal (priorly three, now four years), the Netherlands (three years for research universities, four years for universities of applied sciences), New Zealand (honours degree), Nigeria, People's Republic of China, Pakistan (four or five years), the Philippines (four or five years), Puerto Rico, Romania, Russia, Saudi Arabia, Scotland (Honours Degree), Serbia (three or four years), Spain (in Spain a 2015 Royal Decree will allow 3-year BSc degrees to coexist with current 4-year ones. It will be in force starting September 2015. However most universities have agreed not to implement the new system until September 2017), South Africa (fourth year is elective — to obtain an Honours degree, which is normally a requirement for selection into a master's degree programme), South Korea, Sri Lanka (three four or five (specialised) years), Taiwan, Thailand, Tunisia (Only Bachelor of Science in Business Administration is available, solely awarded by Tunis Business School), Turkey, Ukraine, United States, Uruguay,  Yemen, Zambia (four or five years).
Romania (four or five years), Bangladesh (four or five years), Cuba (five years), Greece (four or five years), Peru, Argentina, Colombia (starting to change to 4 years), Brazil (five years), Mexico (4.5 years), Chile, Venezuela, 5 years ), Egypt (four or five years), Haiti (four or five years).
Nigeria (four to five years), 6 months dedicated to SIWES (Students Industrial Work Exchange Scheme) but for most sciences and all engineering courses only. A semester for project work/thesis not excluding course work during the bachelor thesis. Excluding 1 year for the compulsory National Youth Service Corps (NYSC), para-military and civil service.
In Algeria, the student presents a thesis in front of a Jury at the end of the fifth year.
In Chile, some undergraduate majors such as engineering and geology are designed as 6 year programs.     However, in practice it is not uncommon for students to complete such programs over the course of 10 years, while studying full-time without leaves of absence.  This is in part due to a strict grading system where the highest grade of a typical class can be as low as 60% (C-) and the high frequency of protests and strikes organized by student federations and teacher unions, such as the 2011–13 Chilean student protests.
There are studies that suggest a direct correlation between reduced social mobility and differences unique to the Chilean higher education system.