Short answer
Band 4.0–4.5 is a solid, middle-of-the-pack result — CEFR B2, "upper-intermediate." It's enough for most mid-tier university programs and many state universities, but it falls short of the 5.0+ that competitive and top-20 programs typically expect. Whether it's "good" depends entirely on your specific target, not on the number itself.
Is band 4.0 good?
Band 4.0 (≈ old-scale 72–86) is a common minimum for undergraduate admission at many state and mid-tier universities. It signals you can follow most coursework and communicate reliably, though dense academic material may still take real effort. If your target school lists "72" or "4.0" as its requirement, this band clears the bar — but it's rarely enough for a competitive scholarship or a top-ranked program.
Is band 4.5 good?
Band 4.5 (≈ old-scale 87–99) sits right at the edge between B2 and C1. It's a meaningfully stronger result than 4.0 — many mid-tier programs treat it as comfortably above their minimum — and it's within reach of some competitive programs, though most top-20 schools still prefer 5.0+. If you're at 4.5 and your target requires 5.0, you're one focused study cycle away, not starting over.
How to know for sure
Bands don't carry a universal "good/bad" label — only your target program's published requirement does. Check university requirements by band to look up typical tiers, and see the full band breakdown for what 4.0 and 4.5 mean in terms of real ability.
If you need to move from 4.0 to 4.5 (or higher)
A half-band jump is a realistic, achievable target with focused practice — see how long TOEFL prep typically takes for a study-time estimate based on your gap.
Confirm your current band
If you're not sure whether you're closer to 4.0 or 4.5 right now, a real diagnostic beats guessing.