From a lending perspective, a bad credit score is one in the low-to-mid 500s or lower. With scores that low, you may not be eligible for loans or credit, and if you are, you’ll get extremely unfavorable terms and high interest rates.
From a technical perspective FICO and VantageScore label scores within certain ranges as “Poor” or “Very Poor.” Those ranges are:
FICO: 300–579
VantageScore: 300–499 (Very Poor); 500–600 (Poor)