How accurate are budget weight plates compared to their stamped weight?

Specialist-community testing is mixed. An r/homegym member who weighed CAP cast iron plates found them within roughly 1% to 2.7% of stamped weight, which most lifters consider acceptable. However, other r/homegym posters caution that some budget bumper plates can read under their stamped weight, so if exact loading matters to you, calibrated plates or a scale check are worth considering.