Color-coding a schedule sounds simple until you're three weeks in and every color means something different than it did when you started. A good color system is designed once, with a small number of rules, and then left alone.
Pick a coding logic before you pick colors
There are really only three sensible ways to code a schedule: by category (work, study, personal), by priority (must-do, should-do, optional), or by energy level (deep focus, low-effort admin, recovery). Choose one logic and stick to it — mixing systems is what causes the color chart to stop meaning anything.
Limit yourself to five or six colors
Beyond six categories, colors start to look similar enough that you need to squint at the legend anyway, which defeats the point of color-coding in the first place. If you find yourself wanting a seventh color, it usually means two of your existing categories should be merged.
Keep the highest-priority color the boldest
Reserve your most visually strong color (often a warm color like amber or red) for whatever matters most — deadlines, exams, non-negotiable commitments. Muted colors like soft blues and greens work well for routine or flexible blocks. This way, a glance at the week immediately shows you where the pressure points are.
Apply the same system everywhere
If you use color for your class timetable, use the same palette for your study planner and your work schedule too. Consistency across every schedule you keep means you don't have to re-learn a new color key every time you switch tools.
Review the system monthly
As your responsibilities change, your categories will drift out of date. Once a month, check whether your colors still map to what actually matters — a five-minute check that keeps the whole system useful instead of just decorative.