The formula
hours for a topic = total × (weight × difficulty) ÷ sum of them all
Where it comes from
Splitting time equally is what everyone does and it is exactly what not to do: giving the same hours to a topic worth 5 % of the exam and one worth 30 % is giving marks away. A sensible split multiplies what each topic is worth by what it costs you, because both factors pull the same way: an important, difficult topic is where each hour pays off most.
How to work it out by hand
- List each topic with its weight in the exam and how hard you find it, from 1 to 5
- Multiply weight by difficulty: that is its priority
- Add up the priorities of every topic
- Share the hours out in proportion to each priority
What is worth knowing
Difficulty is the subjective part and it has to be set honestly, which is not the same as setting it high everywhere: if every topic is a five, the split goes back to being proportional to weight alone. It is also worth revisiting the plan halfway through, because difficulty estimated at the start rarely matches the real thing. The table shows the equal split alongside precisely so you can see where the hours that move are coming from.