Assessment of fluid balance has an integral role in management of critically ill patients. Fluid status measurement is multifactorial, comprising of clinical examination, biochemical investigation, and fluid balance records. Error in fluid balance record is well published, as are the adverse outcomes that result from poor fluid control. The current audit was organised to assess the degree of arithmetic error in fluid balance records in Hawke’s Bay Intensive Care Unit (ICU); secondary aims included use and effect of certain diuretic/antidiuretic agents, change in patient fluid status, and change in weight during admission. Twenty ventilated patients admitted to Hawke’s Bay ICU over 14 days (between 1st January 2020 and 24th December 2020) were randomly selected for audit. Twenty-four-hour fluid balance charts were checked, and data regarding secondary outcomes was collected. Seventy point one percent of audited charts were correct, within 0-10 ml from the true fluid balance. Incongruence between change in weight and cumulative fluid balance for 14-day of admission described a 1300 g fluid weight discrepancy, explained by insensible fluid loss.