Is Khan Academy enough to learn maths?
Mostly, yes. The lessons are good, the coverage is broad, and it costs nothing. There are three things it doesn't do, and they happen to be the three places self-study usually stalls.
Updated July 2026
Let us start with the concession, because it is real. Khan Academy is one of the best things on the internet. The explanations are patient, the practice sets are solid, the coverage runs from counting to multivariable calculus, and a nonprofit gives it all away. If someone has the discipline to work through it end to end, they will learn real mathematics. Nothing below argues otherwise.
But most adults who start a maths course online do not finish it, and the reasons are rarely about lesson quality. They are about three structural jobs that lessons alone cannot do.
1. Diagnosis: which of 1,000 concepts are you missing?
Khan Academy asks you to choose a course, and within one it lets you test out of units. What it cannot tell you is where, across the whole of mathematics, your knowledge actually ends. An adult with shaky fractions who enrols in Algebra 1 will meet that gap on week two, experience it as being bad at algebra, and quit. The gap was diagnosable. Nothing in a course-shaped product is built to diagnose it, because the course was chosen before the question was asked.
2. Sequencing: a playlist is not a map
Courses sequence material the way school terms need it delivered: linearly, one cohort, one pace. But mathematical knowledge is a dependency graph, and your gaps do not respect course boundaries. The efficient route for you might take three sections of pre-algebra, skip half of geometry, and rejoin at trigonometry. No playlist can express that route; a prerequisite map can, and it is why Consiliae is built as one.
3. Retention: finishing a unit is not keeping it
The third gap is the quiet one. Memory for mathematics decays on a schedule, and the only known fix is reviewing material at expanding intervals just before it fades. Khan Academy’s practice lives inside each course; once you move on, nothing brings last month’s concepts back at the right moment. Study for six months without scheduled review and a large share of the early material is already gone, which is how people finish a course yet feel no better at maths. Consiliae schedules every mastered concept into spaced review automatically, so what you learn in week one is still there in month six.
The same comparison, in one table
| Khan Academy | Consiliae | |
|---|---|---|
| Lessons | Video lessons and practice sets, arithmetic through calculus. Genuinely good. | Written first-principles explanations with graded practice per concept. |
| Price | Free, nonprofit. | Paid subscription; the scan and concept library are free. |
| Diagnosis | You pick a course and can test out of units within it. Which course, and which gaps you carry from earlier ones, is on you. | A placement scan across the whole prerequisite map finds your actual frontier. |
| Sequencing | Courses and units in school order, one course at a time. | One prerequisite graph across all of maths; your route skips what you know. |
| Retention | Practice lives inside each course; nothing schedules review after you move on. | Spaced review resurfaces every mastered concept before it fades. |
So: is Khan Academy enough? For lessons, yes. For knowing where to start, what order to go in, and whether any of it sticks, it was never trying to be. Those three jobs are the product Consiliae is, and the two work perfectly well side by side. If you have concluded you want one tool doing all of it, our full comparison lays out that decision honestly.
Questions
- Is Khan Academy free?
- Yes, completely. It is a nonprofit, there is no paid tier, and the maths courses run from early arithmetic through calculus and beyond. If cost is the constraint, use it without hesitation.
- Is Khan Academy good for adults relearning maths?
- The lessons work at any age. The friction for adults is structural: you have to guess which course to enter, courses are sequenced for school delivery rather than around your particular gaps, and nothing outside a course resurfaces old material before it fades. Adults have less time to spend on wrong guesses than school students do.
- Can I use Khan Academy and Consiliae together?
- Yes, and it is a genuinely good combination. Consiliae maps what you know and schedules exactly what to work on and when to review it; Khan Academy offers an alternative set of free lessons if you want a second explanation of a concept.