Car rental KPIs: how to calculate utilization, RPD and RPU

Short answer: four metrics, four formulas

These definitions follow the metric definitions in the Hertz and Avis Budget Group annual reports (Form 10-K). Avis also notes that its calculation may not be comparable with similarly named metrics at other companies; here we give simple versions a small or mid-sized rental company can apply.

The basic unit: a rental day

All four metrics rest on the rental day: the total number of 24-hour periods vehicles spend on rent. Hertz counts a partial period as a full day, so a 3.5-day rental is 4 rental days. Use the same rule as your contract pricing, or RPD will come out too high or too low.

Utilization: how much of the fleet is working?

Avis defines utilization as rental days divided by available rental days, which are the average rental fleet times the number of days in the period. Hertz also removes cars held for sale from the fleet, but not days in the workshop. A car in service, after an accident or standing idle therefore lowers the rate. That is deliberate: service time is a productivity issue too.

Revenue per day (RPD): your price level

RPD is rental revenue divided by rental days, the industry's version of the average daily rate (ADR). It shows the effect of pricing decisions most directly. Decide at the start whether you include extras (child seats, full cover) and always calculate it the same way.

Revenue per unit (RPU): what does one car earn a month?

RPU is revenue divided by the average fleet and the number of months. Hertz uses it to measure revenue productivity relative to the fleet, whether cars are owned or leased. RPU is in fact the product of the other two: RPU = RPD × utilization × days in the month. A decision that raises price but lowers utilization can leave RPU flat, which makes RPU the quickest way to read both together.

Depreciation per unit (DPU): what the car costs

DPU is depreciation for the period divided by the average fleet and the number of months. Hertz says the metric reflects how it manages vehicle costs and allows comparison with other rental companies. The gap between RPU and DPU roughly shows what a car leaves each month before operating costs.

A worked example for a 20-car fleet

Take a 20-car fleet over a 30-day month. The figures are built to show the mechanism; they are not industry averages.

If the same fleet raises prices by 10% and utilization falls from 75% to 66%, RPD rises to ₺3,300 but RPU drops to ₺65,340. A manager looking only at RPD would call the decision a success; RPU shows otherwise.

Common mistakes

• Using the fleet count at month end: cars added or sold during the month distort the denominator. Work out the average fleet from the days each car was in the fleet.
• Comparing half a month with a full one: do not compare the first 20 days of this month with the whole of last month; compare up to the same day.
• Counting cancelled and pending bookings: a rental that did not happen is not a rental day.
• Booking partner-fulfilled jobs to your own fleet: if your own car did not work, it inflates your utilization.

Where to find these metrics in RentOkey

The Fleet metrics report in RentOkey's Report Library gives all four metrics month by month and against the same period last year; each formula is shown in the report and the table exports to Excel in one click. See Reporting and fleet analytics. For turning the metrics into pricing and fleet decisions, read Car rental fleet profitability metrics.

Sources

• Hertz Global Holdings, 2024 annual report (Form 10-K) — definitions of Transaction Days, Vehicle Utilization, Total RPD, Total RPU and Depreciation Per Unit.
• Avis Budget Group, 2024 annual report (Form 10-K) — definitions of rental days, revenue per day and vehicle utilization.