Everything You Need to Know About Car Measurements and Specs

How to decode the numbers on a spec sheet into real-world examples.

Benjamin Hunting | 

Nov 15, 2024 | 5 min read

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Automotive spec sheets are loaded with data. It can be overwhelming trying to figure out how the numbers and measures translate to how a vehicle can fit your particular needs.

With that in mind, here's an explainer of some of the most common car measurements and specs to help you understand the numbers game when looking at a potential vehicle purchase.

Cargo Room Measurements

Cargo room describes the amount of dedicated storage space provided in an automobile. For a traditional sedan or coupe, cargo room refers to the size of its trunk. In a hatchback or sport-utility vehicle, it's the space underneath the hatch, behind the rear seat. SUVs often come with a second cargo measurement that describes the amount of storage space made available with the rear seats folded down, as measured from the hatch opening all the way to the backs of the front seats.

These two figures, although similar, are measured differently. Open-area spaces are calculated by volume, factoring in the height, width, and depth of a cargo area. Trunk sizes are measured using luggage-like blocks, according to a standard provided by the Society of Automotive Engineers (SAE).

Automakers often put their own spin on this testing, which can make numbers difficult to compare from one vehicle to the next. The official figure provided by an automaker takes into account the entire floor-to-ceiling volume, expressed in cubic-feet (cu-ft), but since few people transport cargo that can occupy every nook and cranny, third-party testing often substitutes luggage or boxes to provide a more real-world sense of overall capacity.

Height And Width of the Vehicle

A vehicle's measurements indicate its overall size but don't necessarily refer exclusively to its body panels. Roof racks and spoilers can all come into play when measuring the height and length of an automobile, which are measured from the very tip of each respective dimension. This is why different trim levels of the same car or truck can sometimes post varying figures, despite sharing the same body shape. Width, however, typically does not include side mirrors in that measurement, across the widest spot on the body.

Legroom, Headroom, and Hiproom

Legroom

Legroom is intended to provide an objective illustration of the space available for passengers to stretch out their legs when sitting in a vehicle. While there is a standard from the SAE for measuring this dimension (involving the distance from the hip to the ankle plus a certain amount of additional distance), there is a fair degree of variance in how car companies choose to employ it.

The key variable is seating position. Specifically, the position of the seat being measured and those in front or behind it can change the measurement.

Headroom

The term headroom is a little misleading. While legroom specifically looks at the amount of space available for a driver or passenger's legs while seated, headroom doesn't measure the gap between an average person's cranium and the roof of the automobile. Instead, it documents the distance between the bottom of the seat and the headliner.

Given that not everyone is the same height or has the same proportions, the term headroom has become a general catchall to refer to the amount of space available for comfort under a vehicle's roof. Headroom can also vary depending on how adjustable a seat's height might be.

Hiproom

Of the three seating-related measurements, hiproom is the most straightforward. Simply put, it's the width of a car seat, or the amount of space available to plunk one's posterior down as a passenger or driver.

Vehicle Curb Weight Is the Relevant Measurement

Of the multiple weights listed in the vehicle's specifications, the most helpful measure is curb weight. This refers to how much a vehicle weighs when loaded with all of its standard equipment, fluids — such as engine oil, coolant, brake fluid — and a full tank of gas.

Conversely, dry weight refers to how much a car or truck tips the scales minus its fluids and fuel. This isn't exactly a practical measure, given that it's unlikely for you to encounter a fully drained vehicle, even when towing.

For each of these weights, passengers and cargo are not included in the calculation.

Ground Clearance Makes a Difference for Off-Roading

If you've ever shopped for a truck or an SUV, chances are you've come across the term ground clearance. Usually represented in inches, ground clearance is an important concern for anyone who intends to head off-road and explore terrain more treacherous than a paved highway.

Ground clearance refers to the space between the lowest part of an automobile and any obstacles below it. For some models, this low point might be a differential cover or a suspension component, while for others it could be the leading edge of the front bumper or the lower lip of the rear.

Exhaust systems and tailpipes also tend to be low points, especially at the back of a truck. The number provides an idea of how much of an air gap a vehicle has when driving over an uneven surface before it begins scraping components.

Benjamin Hunting

Benjamin Hunting is a writer and podcast host who contributes to a number of newspapers, automotive magazines, and online publications. More than a decade into his career, he enjoys keeping the shiny side up during track days and always has one too many classic vehicle projects partially disassembled in his garage at any given time. Remember, if it's not leaking, it's probably empty.