Logbook Calculator
Calculate business-use percentage and compare trip totals with odometer travel.
Odometer readings
Use whole kilometres for the same vehicle and period.
Recorded travel
Business travel within these odometer readings.
Optional. Include private trips, or leave blank to skip this check.
63.71%
Recorded trip kilometres match the odometer travel.
3,480 km
1,263 km
0 km
Fictional example. Percentage rounded to two decimal places. A matching total does not establish a valid deduction.
Kilometres to Business Use
This logbook calculator divides business kilometres by total travel and multiplies by 100 to find the business-use percentage. Total travel is the closing odometer reading less the opening reading. Private kilometres are total travel less business kilometres.
This logbook method calculator checks the business-use percentage for tax records. Learner-driver hours and driver-hours compliance records measure driving time and need their own records.
Use readings and trips from the same vehicle and period. Enter whole kilometres. The calculator rejects business kilometres greater than total travel and closing readings at or below the opening reading.
In the fictional example, the odometer rises from 58,420 km to 61,900 km. Total travel is 3,480 km, including 2,217 business kilometres. The calculation is 2,217 divided by 3,480, multiplied by 100, giving 63.71% business use and 1,263 private kilometres.
Reconcile the Logbook
Compare the total of all recorded trips with the odometer difference to find travel that needs checking. Include private trips in this optional total. A business-trips-only total cannot reconcile all vehicle travel.
For the same example, a trip total of 3,450 km leaves 30 km unrecorded. A total of 3,510 km exceeds odometer travel by 30 km. Check missing journeys, duplicated entries and the opening or closing readings before changing the business kilometres.
A matching total confirms only that the two totals agree. It cannot confirm each trip’s purpose or detect errors that cancel each other out. The business-use percentage always uses odometer travel as its denominator, even when recorded trips differ.
The Australian Taxation Office (ATO) lists the records a motor vehicle logbook needs. Keep the period’s start and end readings, journey details and vehicle identification with the calculation.
Using the Percentage
The percentage describes the kilometres you entered. A deduction also needs eligible expenses and evidence that the business travel qualifies. Give the reconciled records to the accountant for review before applying the percentage to car expenses.
The ATO’s logbook method guidance requires a representative period of 12 continuous weeks. A logbook can support later years for up to five years when vehicle use remains representative. Keep annual odometer records and the expense evidence required for the claim.
This tool checks distances only. It does not check the length of the logbook period, classify trips or calculate a tax deduction. Enter totals here without client names or vehicle registration details. The calculator sends no entries to Tax Genie or the ATO and saves none in browser storage.