CAT Mini Excavator Sizes and Models Explained Parts OnlineSep 23, 2026 Share Caterpillar mini excavator model numbers broadly track operating weight in metric tonnes. A 305 sits near the five tonne class and a 308 near eight tonnes. That convention also answers the question most often asked about the range: a CAT 320 is not a mini excavator, because the number places it around twenty tonnes. The Essentials Naming logic: the number approximates operating weight in metric tonnes Mini range: the 300 series, from roughly one tonne up to around ten Not a mini: the 320 and above are full size excavators Common suffixes: CR for compact radius, plus generation letters Reorder most: hydraulic, engine, fuel and air filters Order against: the CAT part number and the machine serial, not the model alone What Counts as a CAT Mini Excavator? Mini excavators are the compact end of the excavator range, generally understood in the industry as machines under about ten tonnes operating weight. Caterpillar covers this segment with its 300 series, spanning small one and two tonne machines through to larger units approaching the top of the compact class. Above that threshold the machines are classed as full size excavators, and the naming continues on the same logic. This is why the 320, a common source of confusion, falls outside the mini category. Its number places it in the twenty tonne class, which is a different machine entirely in terms of transport, ground pressure and parts. Some in the trade separate the range further, treating machines under roughly six tonnes as minis and those between six and ten tonnes as midi excavators. Caterpillar does not require that distinction for parts purposes, but you will encounter it when shopping used machines. How Do CAT Mini Excavator Model Numbers Work? The number is the size indicator, and it approximates operating weight in metric tonnes. That makes the range unusually easy to read once you know the convention. 301 and 302 sit at the one to two tonne end, the machines that fit through gates and into back gardens 303 through 306 cover the volume of utility, landscaping and small site work 307 through 310 are the large end of the compact class, approaching full size capability Decimal variants appear at the small end, such as 301.5 and 301.7, where a full tonne step would be too coarse a division. Letter suffixes carry additional meaning. CR indicates a compact radius machine, where the counterweight stays within or close to the track width so the machine can slew in confined spaces without the tail swinging into an obstruction. Generation letters follow the size designation and mark successive updates to the same machine class, in the same way they do across Caterpillar's compact loader line. What Sizes Do CAT Mini Excavators Come In? Practically, the range covers three working tiers, and the right tier is decided by access and by what the machine has to lift rather than by dig depth alone. Tier Approximate class Typical work Sub-compact 1 to 2 tonnes Gated access, indoor demolition, utility repairs Compact 3 to 6 tonnes Landscaping, drainage, footings, general site work Large compact 7 to 10 tonnes Site prep, trenching, heavier construction Transport is the constraint most often underestimated. Moving up a tier changes trailer and towing requirements, and that recurring cost frequently outweighs the capability gained. What Is the Difference Between the D and D2 Series? Generation suffixes mark revisions of the same size class rather than different machines. Caterpillar has updated the compact excavator line repeatedly, and between generations has revised engines to meet changing emissions standards, updated cab and control layouts, and altered hydraulic and filtration arrangements. For parts, the generation is not a detail. It frequently determines the part number. Two machines wearing the same size number from different generations can take different filters, different cab glass and different hydraulic components. Treat the size number as identifying the family and the suffix as identifying the machine. When a listing does not state a generation, verify against the serial number before ordering. Where Is the Serial Number on a CAT Mini Excavator? The product identification plate is generally mounted on the machine frame, commonly on the side of the upper structure or within the operator station. Caterpillar machines carry a serial prefix followed by a sequence, and parts listings frequently need that prefix rather than the model number alone. Record three things before ordering: Model and any suffix, including CR where applicable Full product identification number from the frame plate Engine serial number, stamped separately on the engine block The engine serial matters more on compact excavators than many owners expect, because these machines run engines shared across several Caterpillar product lines. Filters and engine components are matched against the engine, not the excavator. What Are the Specs for Common CAT Mini Excavator Models? Four specifications decide whether a machine suits a job: operating weight, dig depth, reach and hydraulic flow. All four vary by model, by generation, and by configuration such as boom type or track width. Read the figures from Caterpillar's operator manual for your specific model and serial range rather than working from a number remembered off another machine. What holds generally: Operating weight is approximated by the model number and governs transport requirements and ground pressure Dig depth and reach rise with machine size but also change with boom configuration Auxiliary hydraulic flow determines which attachments will run, and is the first spec to confirm when matching a breaker or auger Variable angle boom and long reach configurations exist within the range and change reach figures substantially, which is why a specification table alone will not tell you what a specific used machine can do. What Service Parts Do CAT Mini Excavators Need Most? Compact excavators work in abrasive conditions and their filtration works hard. Based on our catalog data, filters are the parts owners reorder most consistently, followed by cab glass and undercarriage components. Hydraulic filtration is the recurring item. Spin on hydraulic filters used across Caterpillar applications include the Spin-On Hydraulic Filter replacing CAT 3G6926, the Spin-On Hydraulic Filter replacing CAT 3G6928, and the Spin-On Hydraulic Filter replacing CAT MCF00321. Because Caterpillar filter applications span many machine families, the OEM number is the only dependable way to match one. Read it from the filter you are removing or from the maintenance section of the operator manual. Browse the range at Hydraulic Filters or across Caterpillar Parts. Caterpillar publishes service intervals per model in the operator manual. Machines working in sandy or dusty ground, or running hydraulic attachments for extended periods, need shorter intervals than the published baseline. How Do I Make Sure a Part Fits My CAT Mini Excavator? Model level assumptions are unreliable across generations. Work from the part number. Read the CAT part number off the component being replaced Record the model, suffix and full serial from the frame plate Use the engine serial for filters and engine components Cross check the OEM number against the aftermarket listing before ordering Quality aftermarket filters are built to meet or exceed OEM specifications and are the more economical route for scheduled maintenance. Customers are responsible for verifying fitment. If you are working from a model number alone and cannot find a part number, send your machine serial to sales@partsonline.com and our team will confirm the match. Consult a certified mechanic for hydraulic system work. Frequently Asked Questions Is a CAT 320 a mini excavator? No. Caterpillar model numbers approximate operating weight in metric tonnes, which places the 320 in the twenty tonne class. Mini excavators are the 300 series, generally under about ten tonnes. How much does a CAT mini excavator cost? New and used pricing varies widely by size class, generation, hours and configuration, so a current dealer quote is the only reliable figure. Running costs are driven mainly by filters, undercarriage wear and hydraulic maintenance. Are CAT mini excavators any good? Caterpillar compact excavators are well regarded for hydraulic performance, build quality and dealer support. As with any used machine, hours and maintenance history matter more than the badge. Who makes CAT mini excavators? Caterpillar manufactures its own compact excavator range, produced across several global facilities. Engines used in the range are shared with other Caterpillar product lines, which is why engine parts are ordered against the engine serial. What CAT mini excavator models are there? The mini range is the 300 series, running from sub-compact one and two tonne machines through to units approaching ten tonnes, including decimal variants at the small end and CR compact radius configurations. What does CR mean on a CAT mini excavator? CR stands for compact radius. The counterweight stays within or close to the track width, so the machine can slew in confined spaces without the tail swinging into surrounding obstructions. What is the difference between a mini and a midi excavator? The terms are trade conventions rather than manufacturer categories. Machines under roughly six tonnes are commonly called minis, and those between six and ten tonnes midis. Both fall within Caterpillar's 300 series. How do I know which filter fits my CAT mini excavator? Match the CAT part number rather than the machine model, since filter applications span many machine families. Read the number from the filter being removed or from the maintenance section of your operator manual, then cross reference. Share Next article Join Us A short sentence describing what someone will receive by subscribing Your email Subscribe100% free, Unsubscribe any time! Follow us