Definition
A fuel system instrument that continuously calculates and displays the total quantity of fuel remaining on board an aircraft by combining a known starting fuel quantity with the running total of fuel consumed, as measured by fuel-flow sensors. A totalizer may also display fuel used, fuel flow, and time remaining at current consumption.
Plain English
A cockpit gauge that keeps a running tally of how much fuel is left by starting with the amount you put in and subtracting what the engines have burned.
Context Anchor
Most often seen in aircraft fuel systems, where a fuel totalizer helps the pilot track how much fuel has been used or how much remains.
Derivation
From 'total' plus the suffix '-izer' (something that performs the action). The name describes its job: it totals things up — specifically, fuel used and fuel remaining.
Why Pilots Care
Provides precise cumulative fuel data essential for accurate flight planning, reserve calculations, and avoiding fuel exhaustion.
Analogy
A totalizer is like a trip odometer in a car. The speedometer shows how fast you are going right now; the trip odometer adds up how far you have gone. A totalizer does the adding-up job for fuel or another measured amount.
Intuition Check
A totalizer is not mainly a rate gauge. It shows the accumulated total over time, such as gallons used since it was set.
Example Sentence 1
Before takeoff, the pilot topped off the tanks and reset the totalizer to 92 gallons.
Example Sentence 2
When the totalizer indicated only 12 gallons remaining, the crew initiated a diversion to the nearest suitable airport.