Are consumer fingertip pulse oximeters accurate enough to rely on?

For trend-tracking, yes; for clinical decisions, with caveats. A study indexed on pmc.ncbi.nlm.nih.gov found the Zacurate Pro Series 500DL hit roughly 90% accuracy against reference devices, which is strong for a consumer unit but still below hospital-grade Masimo or Nonin sensors. Across the reviewers we read, the consensus is that any FDA-cleared finger oximeter is fine for spot checks, but readings can swing 2–4 points based on cold fingers, nail polish, motion, and perfusion.