ASVAB General Science: format, topics and how to prepare
Last checked October 14, 2026 · Sources: Department of Defense What to Expect page, Fact Sheet and sample questions; Army and Air Force ASVAB pages
ASVAB General Science (GS) tests your knowledge of the physical and biological sciences. It is the first subtest you take. It doesn’t count toward your AFQT, but the Army and Air Force use it in job scores for electronics and technical work, so it can decide which jobs open up to you.
What General Science tests
The Department of Defense describes General Science as knowledge of physical and biological sciences, in the Science and Technical domain. The Air Force breaks the content down further into life science, earth and space science, and physical science. Questions are short and fact-based: you either know the principle or you don’t, which makes steady review more useful than test-day strategy.
Format and timing
| Computer (CAT-ASVAB) | Paper (P&P-ASVAB) | |
|---|---|---|
| Scored questions | 15 | 25 |
| Time limit | 12 minutes (25 with tryouts) | 11 minutes |
| Average time per question | About 48 seconds | About 26 seconds |
| Go back and change answers | No | Yes, within this subtest |
Source: officialasvab.com What to Expect page and Fact Sheet, checked October 14, 2026. Time per question is our calculation.
Because General Science comes first, it is also where test-day nerves show up. Some prep books still show the computer version as 16 questions in 8 minutes; the Department of Defense’s current pages say 15 scored questions in 12 minutes.
Where General Science counts
| Branch | Job scores that use General Science |
|---|---|
| Army | Electronics, General Maintenance and Skilled Technical line scores |
| Air Force | Electronics MAGE score |
| Coast Guard | Some A-school composites; the 2021 Information Systems Technician example used MK+EI+GS |
Sources: goarmy.com and airforce.com ASVAB pages, checked October 14, 2026.
If you are aiming at electronics, maintenance or technical jobs, General Science deserves real study time even though it isn’t part of the AFQT. See our Army, Air Force and Coast Guard score guides.
Topics to review, with examples
The facts below are standard high school science, chosen by us to show the range of the three areas the Air Force names. They are not real ASVAB questions.
| Area | Example review points |
|---|---|
| Life science | Photosynthesis turns light energy, carbon dioxide and water into glucose and oxygen. Mitochondria release energy for the cell. Red blood cells carry oxygen. |
| Earth and space science | Earth’s rotation causes day and night; its tilt causes the seasons. The three rock types are igneous, sedimentary and metamorphic. |
| Physical science | An element’s atomic number is its number of protons. Water boils at 100°C (212°F) at sea level. Force equals mass times acceleration. |
Example review points by area. Our selection.
It also helps to know basic units (meters, grams, liters, degrees Celsius), the states of matter, simple food chains, the main body systems, and the planets’ order from the sun.
Practice questions
Our own examples in the short, fact-based style General Science uses:
- Which gas do plants release during photosynthesis? Oxygen. They take in carbon dioxide and release oxygen.
- What causes the seasons on Earth? The tilt of Earth’s axis, which changes how directly sunlight reaches each hemisphere through the year.
- An atom has 6 protons. What is its atomic number? 6. The atomic number is the number of protons; this element is carbon.
- A 10 kg cart accelerates at 2 m/s². What force is acting on it? Force equals mass times acceleration: 10 × 2 = 20 newtons.
- Which type of rock forms from cooled magma or lava? Igneous rock.
How to prepare for General Science
Try the Department of Defense's free General Science sample questions to see which of the three areas you know least.
Spend a few days each on life, earth and space, and physical science rather than mixing them from the start.
Write short fact cards for definitions, processes and units, and review them daily.
A high school biology, earth science or physical science textbook covers most of what this subtest draws on.
Practice 15 questions in 12 minutes so the pace feels normal by test day.
On the computer version, keep giving real answers to the end, because random guesses near the end of a subtest are penalized. On paper, fill in every blank if time runs out. Our free ASVAB resources page lists no-cost practice.
Mistakes that cost General Science points
- Skipping it entirely because it isn’t in the AFQT, then missing the line score a target job needs.
- Mixing up similar terms, such as mass and weight, or mitosis and meiosis.
- Forgetting unit conversions between metric and US measures.
- Rushing the first subtest because of nerves.
Common questions about ASVAB General Science
How many questions are on ASVAB General Science?
On the computer version, 15 scored questions in 12 minutes, or 25 minutes if tryout questions are added. On the paper version, 25 questions in 11 minutes.
Does General Science count toward the AFQT?
No. The AFQT uses only Arithmetic Reasoning, Mathematics Knowledge, Word Knowledge and Paragraph Comprehension. General Science feeds job scores instead.
What topics are on ASVAB General Science?
Life science, earth and space science, and physical science, according to the Air Force.
Which jobs need a good General Science score?
In the Army, Electronics, General Maintenance and Skilled Technical jobs. In the Air Force, Electronics jobs.
When does General Science come on the ASVAB?
It is the first subtest on both the computer and paper versions.
See also our guides to Mathematics Knowledge and Arithmetic Reasoning, or go back to the ASVAB overview. MockTestPrep is independent and is not affiliated with the Department of Defense or any service branch.