This glossary defines the terms used by carriers, 3PLs, WMS vendors, and dimensioning system manufacturers when discussing freight measurement, dimensional weight billing, and automated dimensioning technology. Terms are organized alphabetically within thematic sections.
The physical weight of a shipment as measured on a calibrated scale, expressed in kilograms or pounds. Carriers compare actual weight to dimensional weight and bill on the higher of the two values. Also called gross weight or scale weight.
The smallest rectangular box, aligned to the x, y, and z axes (length, width, height), that completely contains a three-dimensional object. All carrier DIM weight calculations are based on the AABB of the shipment, regardless of the object’s actual shape. A cylindrical drum and a box of the same overall dimensions produce the same AABB.
The weight used as the basis for carrier freight charges. Billable weight equals the higher of actual weight or dimensional weight. Some carriers apply a minimum billable weight per shipment regardless of measured weight.
The freight industry term for billable weight, used most commonly in air cargo. Under IATA standards, chargeable weight is the higher of actual weight or volumetric weight calculated at the 1:6,000 factor (1 kg per 6,000 cm³).
The number used to convert cubic volume into dimensional weight. Dimensional weight = (L × W × H) ÷ DIM factor. Common DIM factors:
A lower DIM factor results in higher dimensional weight and more aggressive DIM weight billing. Carriers adjust their DIM factor to influence revenue per shipment mix.
A calculated weight representing the space a shipment occupies, used when it is greater than actual weight. Formula: (Length × Width × Height) ÷ DIM factor. DIM weight billing was introduced by carriers to recover revenue on large, lightweight shipments that consume cubic capacity without generating proportional revenue at actual weight rates.
A carrier billing model where freight charges are based on dimensional weight rather than actual weight when the dimensional weight exceeds the actual weight. Now standard practice across all major parcel and air cargo carriers globally.
An NMFC classification system (Classes 50–500) used in LTL (less-than-truckload) freight billing in North America. Freight class is determined primarily by density (weight per cubic foot), with adjustments for stowability, handling difficulty, and liability. Higher class numbers indicate lower density and higher per-hundredweight rates.
The minimum weight a carrier will bill for a shipment regardless of actual or dimensional weight. Common in air cargo (e.g., 45 kg MCW per air waybill) and some LTL lanes. Shipments below the MCW are billed at the MCW rate.
The classification system maintained by the National Motor Freight Traffic Association (NMFTA) that assigns freight classes to commodity types for LTL billing in North America. Each commodity has a primary classification basis—density, stowability, handling, or liability—and a freight class range that carriers use to set rates.
The European and air cargo equivalent of dimensional weight. Calculated identically: (L × W × H) ÷ volumetric factor. IATA uses 6,000 cm³/kg as the standard volumetric factor for air cargo.
A collection of data points in three-dimensional space (x, y, z coordinates) that represents the surface of a scanned object. Dimensioning sensors produce point clouds that cubing software converts into bounding box measurements.
A device attached to the conveyor belt drive that measures belt displacement in real time. In-motion dimensioners use the belt encoder signal to reconstruct accurate length measurements from cross-sectional scan profiles—without it, belt speed variation causes length measurement error.
A pallet or freight dimensioner configured as a portal arch that vehicles (forklifts, pallet jacks) drive through at low speed. The system captures dimensions as the load passes through the arch without requiring the vehicle to stop. Also called a portal dimensioner or forklift dimensioner.
A dimensioning system that captures measurements while items move along a conveyor belt. Items are not stopped for measurement. In-motion dimensioners are the standard technology for high-volume parcel sortation lines processing 1,500–6,000+ items per hour.
A sensor that projects a line of laser light across an object and captures the reflected profile with a camera. Used in dimensioning systems to produce cross-sectional height profiles as items pass through the scan zone. Multiple laser line sensors at different angles are combined to capture top and side dimensions.
A sensing technology that measures distance by emitting laser pulses and measuring the time of flight of the reflected signal. Used in pallet dimensioners and freight scanners to capture 3D models of irregular loads such as shrink-wrapped pallets and open-top containers.
The physical frame structure that mounts dimensioning sensors above and to the sides of a conveyor belt or forklift lane. The arch positions sensors at fixed, calibrated distances from the belt surface to ensure consistent measurement geometry.
A dimensioning system designed to measure loaded pallets, including stacking height and irregular load shapes. Pallet dimensioners typically use LiDAR or structured light and are available in static (pallet placed on platform), drive-through (forklift passes through arch), and fixed-frame (pallet placed in measurement zone) configurations.
A dimensioning system designed to measure individual packages and cartons, typically in the 10 cm to 200 cm range. Parcel dimensioners are available as static stations (operator places item) and in-motion conveyor systems.
A dimensioning system where the item is placed on a measurement platform and held still during measurement. Used in manual or semi-automated receiving stations. Measurement cycle time is typically 1–3 seconds. Contrast with in-motion dimensioner.
A 3D sensing technique that projects a known pattern of light (stripes, dots, or grids) onto a surface and uses the deformation of the pattern to calculate depth. Used in dimensioning systems for high-accuracy static measurement of complex or irregular shapes.
A measurement principle used in LiDAR and some 3D cameras: the sensor emits a signal (laser pulse or modulated light) and measures the time until the reflected signal returns. Distance is calculated as (time × speed of light) ÷ 2. Used in pallet dimensioners and freight scanners.
The application layer between dimensioning hardware and logistics management systems. Cubing software converts raw 3D sensor data into bounding box measurements, applies business rules (DIM weight, freight class, rounding), and delivers structured records to WMS, TMS, or ERP via API, flat file, or database write.
The process for managing items that the dimensioning system cannot process automatically: unreadable barcodes, items outside the measurement envelope, low-confidence scans, oversize detections, or weight variance flags. Exception items are diverted to manual processing queues rather than auto-posted to the WMS.
A programmatic interface that allows the cubing software to send dimension records to a WMS, TMS, or carrier system. Most modern implementations use REST APIs with JSON payloads. Legacy integrations use flat file exports (CSV, XML) or direct database writes.
A scan event where the dimensioner captures dimensions but fails to read the barcode. The dimension record exists but cannot be matched to a shipment without manual barcode entry. No-read rates above 2–3% indicate barcode quality or scanner configuration issues.
A quality metric produced by the cubing software that indicates how reliably the 3D sensor captured the item geometry. Low confidence scores (below a configurable threshold) trigger exception routing. Confidence is affected by item surface reflectivity, packaging material, distance from sensors, and item stability during measurement.
The automation system that assigns each item on a sortation conveyor to a specific sort lane and activates the divert mechanism. The sorter controller receives dimension + barcode + weight data from the dimensioner and uses it (along with carrier and service level data from the WMS) to determine the correct destination lane for each item.
A vendor-specific approval process run by major parcel carriers (FedEx, UPS, DHL) that validates a dimensioning system (hardware + software + installation) for use as the basis of carrier billing. Certified systems must demonstrate accuracy within carrier-specified tolerances (typically ±2–5 mm) under field conditions. Certification is per hardware model, software version, and installation configuration.
A designation indicating that a measurement instrument is approved by a national metrology authority for use in commercial transactions where the measurement determines price or billing. Dimensioning systems used for carrier billing in trade must be legal-for-trade certified in the jurisdiction of use.
A US certification program administered by the National Conference on Weights and Measures (NCWM) that evaluates weighing and measuring instruments for commercial use. NTEP Certificates of Conformance are required for dimensioning systems used in commercial freight billing in the United States.
The International Organization of Legal Metrology recommendation for multi-dimensional measuring instruments used in commercial applications. OIML R 129 defines accuracy classes, test procedures, and performance requirements for dimensioning systems used in freight billing. Compliance with OIML R 129 is required for legal-for-trade certification in many countries.
An electronic document sent by a supplier to a receiver before a shipment arrives, listing expected items, quantities, and packaging. WMS receiving automation (including dimensioning) works most effectively when ASNs are accurate—the WMS matches incoming scan records to open ASN lines to confirm receipt.
The elapsed time from when an inbound shipment arrives at the receiving dock to when inventory is available in the WMS for picking, putaway, or cross-docking. A primary KPI for warehouse inbound efficiency. Industry benchmarks range from under 1 hour (automated) to 24–48 hours (manual).
A unique identifier (barcode or RFID tag) applied to a storage unit (carton, pallet, tote) at the point of receipt. The WMS associates item content, dimensions, weight, and location with the license plate. Dimensioning at receiving triggers automatic license plate generation in most WMS integrations.
The process of assigning warehouse storage locations to SKUs based on velocity, weight, dimensions, and pick frequency. Accurate dimensional data from inbound dimensioning enables slot assignments that match actual item size to location size, improving storage density and pick efficiency.
Standardized containers and pallets used in air cargo to consolidate freight for loading into aircraft. Common ULD types include LD3 (below-deck narrow-body), LD7 (below-deck wide-body), and MD (main-deck pallet). Dimensioning systems at air cargo facilities verify that built ULDs comply with aircraft contour limits before loading.
The guaranteed maximum measurement error of a dimensioning system under specified conditions (item type, belt speed, temperature range). Expressed as ± mm. Example: ±2 mm in length, width, and height at belt speeds up to 2.0 m/s. Accuracy specifications that don’t specify conditions (belt speed, item type, temperature) are incomplete and should not be accepted as performance commitments.
The process of verifying and adjusting a dimensioning system’s measurements against a known reference standard (typically a precision reference cube with certified dimensions). Calibration ensures that measured dimensions match actual dimensions within the specified accuracy tolerance. Frequency depends on operating environment: daily calibration checks are standard for carrier-certified systems.
The range of item dimensions a dimensioning system can accurately measure. Items smaller than the minimum or larger than the maximum of the measurement envelope are outside the system’s operating range and require manual measurement or a different dimensioning system. Defined separately for length, width, and height.
The consistency of a dimensioning system’s measurements when the same item is measured multiple times under identical conditions. A system with high accuracy but low repeatability produces inconsistent results—important in high-volume billing applications where the same SKU is measured thousands of times per day.
The smallest increment of measurement a dimensioning system can detect and report. A system with 1 mm resolution reports dimensions in 1 mm increments. Resolution is not the same as accuracy: a system can have 1 mm resolution but ±5 mm accuracy. For carrier billing, accuracy at the specified resolution is the relevant specification.