The trigonometry you actually need for OMPT-C: almost none

I wrote this post because students keep asking the question in the same shape: "how much trig do I need for the OMPT-C?", usually from deep inside a generic trig course they bought out of caution. The straight answer saves them thirty hours, and it says something bigger about how to prep for the C.

What the OMPT-C syllabus says, chapter by chapter

The OMPT-C syllabus page at omptest.org (read 21 September 2026) lists four chapters and 66 topics. Next to the A and the B the shape is obvious: the C is the first three chapters of the A plus a very small geometry chapter.

The geometry chapter is where the confusion breeds. The official learning goal says the candidate "uses geometric properties of polygons to compute angles, areas, and lengths". Concretely: the hypotenuse of a 6-8-? triangle in your head, the third angle of a triangle from the other two, parallel lines. You will not be asked to solve sin(2x) = 1/2 on an interval, and you will never see a radian. A nervous student reads "geometry" and pattern-matches straight to sine curves; course sellers rarely correct them, since a bigger syllabus sells a bigger course.

Where the OMPT-C marks sit: numbers 35%, geometry 15%

The official learning-assessment page gives the weights: Numbers 35%, Algebra 25%, Linear formulas and equations 25%, Geometry 15%. More than a third of the test is the chapter people skip because it "is just arithmetic". Mapped onto 30 questions (my translation, not an official figure) that is ten or eleven questions on numbers, seven or eight each on algebra and on linear work, and four or five on geometry. Matching drills: exponents and roots plus fractions by hand, polynomials and factoring, linear equations and inequalities, and the angles half of angles and radians.

Two interface rules matter most on the C, because the numbers chapter is all about form. Answers are expected exact: the help centre's own example has -48/408 scoring as -2/17 and not as -0.12. And the C gets the basic on-screen calculator, which shows decimals and never converts to a fraction. The C is also final-answer only, with no partial credit for working. Details in the calculator rules.

The four-week OMPT-C plan in 40 hours

omptest.org recommends 40 hours for the C, so ten hours a week for four weeks. Numbers come first because they carry the most marks and everything later depends on them: you cannot simplify an algebraic fraction if you cannot simplify 48/408. The study planner spaces these blocks against your test date.

Four minutes per question is generous, which is exactly why programmes expect accuracy: the C forgives slowness, never sloppiness. Rehearse checking under time in the last week.

A ten-question OMPT-C self-test, with answers

Pen and paper only, no calculator, timed. The questions are mine, written to the four official chapters and easier than the hard end of the real thing; the point is to find which chapter is rusty.

1. Work out 3/4 + 2/5. Answer: 23/20. Leave it as a fraction; 1.15 is the wrong form.
2. Simplify -48/408 as far as possible. Answer: -2/17 (divide top and bottom by 24).
3. Evaluate 2 - 3 x (-4)^2. Answer: -46. Square first, then multiply, then subtract.
4. Simplify (2x^2)^3. Answer: 8x^6. Cube the coefficient too.
5. Expand (x - 3)(x + 5). Answer: x^2 + 2x - 15.
6. Factorise x^2 - 7x + 12. Answer: (x - 3)(x - 4). Product 12, sum -7.
7. Solve 3(x - 2) = 5x + 4. Answer: x = -5.
8. Solve -2x + 7 > 1. Answer: x < 3. The inequality flips when you divide by -2.
9. Find the line through (1, 2) and (3, 8). Answer: y = 3x - 1. Slope 6/2 = 3, then substitute a point.
10. A right triangle has legs 9 and 12; find the hypotenuse. Two angles of another triangle are 35 and 65 degrees; find the third. Answers: 15, and 80 degrees.

Reading the result. All ten right in under twelve minutes: your prep is pacing work, go straight to timed sets and the mock. Dropped any of 1 to 4: that is week one; do not touch algebra until fractions and powers are automatic. Wrong on 5 or 6: week two. Slow on 7 to 9: formula handling. A pause on 10 is a two-evening fix, because Pythagoras, angle sums and parallel lines cover the whole geometry chapter.

Which programmes ask for OMPT-C, and at what score

The C is the least-used variant. These rows are verified on official pages or on the OMPT registration form for 2026/2027; where a minimum is missing, the official page does not publish one.

Two things stand out. The AUC bar of 70% is the highest C cutoff I know of: 21 of 30 right with no partial credit. And Radboud lists the C as an alternative to the E. The C is 66 topics against the E's 161 and 40 recommended hours against 120, because the E adds statistics and probability that most school leavers have never met, so confirm with Radboud admissions that the C is accepted for your diploma type before you buy.

What to do if you were told "OMPT" with no letter

An offer letter says "pass the OMPT maths test" and nothing else, and the student guesses. Guessing wrong costs either a €240 attempt or eighty hours on chapters you will never see. So: if your programme appears on the OMPT registration form at app.omptest.org, the form shows which letters it accepts, and that list is official. One letter is your answer. Two letters shown (Radboud Psychology shows C and E) means you email admissions one precise question: "Is either acceptable for my diploma, and do you prefer one?" If your programme is not on the form, the "Other institution" option lets you register for any letter, so the letter must come from admissions, never from you. Written instructions from admissions beat the form, and are the one case that qualifies for a refund if they prove wrong. The full decision tree is in which OMPT test do I need.

Two students, two different OMPT-C problems

Student one is applying to AUC Humanities, needs 70%, and has a 1 July results deadline. Her self-test came back with questions 1 to 3 wrong and the rest right but slow. That is a numbers-chapter problem carrying 35% of the marks, so week one gets fourteen hours instead of ten and geometry shrinks to two evenings. She books for the first week of June, leaving room for the second AUC attempt before 1 July, and aims for 78% on the free mock first, because a test-day drop of five to eight points is normal and 70 is a hard floor.

Student two was told "OMPT-E or OMPT-C" by Radboud Psychology and has spent a fortnight on probability because a friend took the E. His self-test was ten out of ten in eleven minutes. For him the C is a pacing exercise and the E is 95 extra topics of risk. He confirms by email that the C is accepted for his diploma, drops the probability, runs two timed mocks a week apart, and books the C: the same 55% bar, a fraction of the study.

Prep from the syllabus, not the test family

The trig-for-C question is one instance of the most expensive habit in placement prep: studying for the OMPT in general instead of your variant in particular. Before any course, mine included, takes your evenings, open your variant's syllabus page and let the chapter names veto your study plan. Then take the free timed mock, put the score through the score estimator, and book when the mock sits five points above your cutoff.