Purpose <p>Temozolomide (TMZ) with concomitant radiation is the standard therapy for treating glioblastomas (GBM) and is dosed based on body surface area (BSA) using a goal dose of 75 mg/m². Neurooncologists have different methods of dosing patients, with some dosing within 5&#xa0;mg of the calculated dose and others rounding to reduce patient burden. We aimed to determine the effect of rounded doses of TMZ on survival.</p> Methods <p>We conducted a single-center retrospective review of 380 patients with GBM from 2013 to 2024. Relevant data was extracted from electronic medical records. Kaplan-Meier curves and Cox regression models were used to determine survival outcomes.</p> Results <p>No significant impact on survival outcomes was observed when distance from the calculated temozolomide dose was analyzed as a continuous variable (<i>p</i> = 0.156), adjusting for MGMT, the extent of resection, radiation fractions, and Karnofsky performance scores (KPS). Even limited to just MGMT-methylated tumors, TMZ dose did not affect survival. BMI had no impact on survival outcomes. Our subgroup analysis revealed that patients with MGMT-methylated tumors, total resection, higher KPS, and ≥ 30 radiation fractions had improved survival (<i>p</i> &lt; 0.01). Dose interruptions were not more likely with doses above 75 mg/m² (14%) than with doses at or below 75 mg/m² (9%) (<i>p</i> = 0.22).</p> Conclusion <p>Rounding temozolomide doses does not significantly impact survival outcomes or risk of treatment interruptions for patients with GBM. These findings may allow neuro-oncologists to prioritize reducing pill burden and treatment costs without compromising patient outcomes.</p>