Petrol Chainsaw Sizes Explained: What Engine CC and Bar Length Do You Need? 25 August 2026 For most home users, a petrol chainsaw between 30cc and 45cc with a 12 to 16-inch guide bar is a sensible choice for pruning, garden clearance and cutting smaller logs. Regular firewood cutting or medium-sized trees may call for 45cc to 60cc and a 16 to 20-inch bar. Larger saws are heavier, harder to control and usually better suited to trained or professional users. As of August 2026, petrol chainsaws sold in the UK range from compact 30cc domestic models with 12-inch bars to professional machines above 75cc with bars of 20 inches or more. The best size is not simply the biggest one you can afford. It is the smallest model that can handle your usual timber safely and without putting the engine under constant strain. Petrol chainsaw size chart: CC, bar length and typical jobs The table below is a practical starting point for choosing a petrol chainsaw. The approved bar sizes vary by make and model, so always check the product specification and operator’s manual before fitting a different bar. Engine size Typical bar length Best suited to Typical user 25cc to 35cc 10 to 14 inches Pruning, small branches, light garden clearance and small logs Home user 35cc to 45cc 14 to 16 inches General garden work, firewood and small trees Home user or occasional landowner 45cc to 60cc 16 to 20 inches Regular firewood, thicker hardwood and medium-sized trees Experienced home user, smallholder or professional 60cc to 75cc 18 to 24 inches Large timber, demanding felling and frequent agricultural or forestry work Trained or professional user More than 75cc 20 inches and above Very large timber, forestry and specialist cutting Professional user These ranges overlap because engine design, power output, chain type, weight and intended use all matter. For example, Husqvarna lists the 50.2cm³ 450S with a recommended bar range of 33cm to 50cm, while MowShop offers the 59.8cc ECHO CS-590 with a 20-inch bar. This is why the model specification matters more than a general CC rule. What does CC mean on a petrol chainsaw? CC means cubic centimetres and measures the engine’s cylinder displacement. You may also see the same figure written as cm³. A higher CC figure usually means the engine can produce more power and pull a longer chain through larger or harder timber. Engine CC does not tell you everything about a chainsaw. Two 50cc saws can have different power outputs, weights and recommended bar lengths. A professional 50cc saw may also cut faster than a cheaper saw with similar engine capacity because of its power-to-weight ratio, chain speed and build quality. Does a higher CC chainsaw cut faster? A higher CC chainsaw can cut faster when its extra power is matched with the correct bar and a sharp chain. It will not make up for a blunt chain, poor tension or the wrong cutting attachment. More CC also brings extra weight, fuel use and purchase cost, so unused power can make a saw more tiring without improving the job. What does chainsaw bar length mean? Chainsaw bar length is the usable length of the guide bar from the front of the saw body to the tip. Common petrol chainsaw bar sizes include 12, 14, 16, 18 and 20 inches. The timber should normally fit within the usable bar length if you want to complete a straightforward cut from one side. A shorter guide bar is lighter and easier to manoeuvre for pruning and snedding. A longer guide bar can reach through wider timber, but it adds weight and gives the engine more chain to drive. Husqvarna’s chainsaw buying advice also recommends choosing the bar according to tree size and operator experience. Is the advertised bar length the exact cutting length? No. The advertised bar length is a nominal measurement and part of the bar sits inside the chainsaw body. The usable cutting length may therefore be slightly shorter. Check the manufacturer’s specification rather than assuming that a 16-inch bar will give a full 16 inches of cutting space. How do engine CC and bar length work together? The engine must have enough power and oiling capacity to drive the chain around the fitted bar under load. A longer bar carries more chain and creates more resistance in the cut. Fitting an oversized bar to a small petrol chainsaw can lead to slow cutting, bogging down, extra clutch wear and overheating. Only use bar and chain combinations approved for your exact chainsaw model. Pitch, gauge, drive-link count and bar mount must match as well as length. If you want to change bar size, check the manual or ask a machinery dealer before buying parts. What size petrol chainsaw do you need for each job? Choose a petrol chainsaw around the timber you cut most often, not the largest tree you might meet once. The following ranges give a useful starting point. What size chainsaw is best for pruning and small branches? A 25cc to 35cc petrol chainsaw with a 10 to 14-inch bar suits ground-level pruning, small branches and light garden clearance. Compact saws are easier to position and less tiring than forestry models. The 30.1cc STIHL MS 162 with a 12-inch bar is one example aimed at home users, firewood cutting and small tree maintenance. For high branches or aerial work, do not climb with a standard rear-handle chainsaw. Use a trained tree professional. What size chainsaw is best for firewood? A 35cc to 50cc petrol chainsaw with a 14 to 18-inch bar suits most domestic firewood. Choose the shorter end for occasional small logs and softwood. Move towards 45cc to 50cc with a 16 or 18-inch bar for regular cutting, wider logs or dense hardwood. For a mixed pile of domestic logs, a well-balanced 16-inch model is often more useful than a heavy saw with a very long bar. It has enough reach for common firewood sizes while staying manageable through repeated cuts. What size chainsaw is best for felling small or medium trees? A 45cc to 60cc petrol chainsaw with a 16 to 20-inch bar is a common range for small to medium tree felling. Tree diameter, species, lean, surrounding buildings and operator competence all affect whether the work is suitable for DIY use. MowShop examples in this class include the STIHL MS 251 with 16 or 18-inch bar options and the Husqvarna 550 XP Mark II with an 18-inch bar. The Husqvarna is a professional model, which shows why engine size alone does not define the intended user. What size chainsaw is best for large trees and forestry? A 60cc to 75cc petrol chainsaw with an 18 to 24-inch bar suits demanding timber work, but this is normally professional territory. Saws in this class are heavier, more powerful and designed for experienced operators who use proper felling methods. Very large trees, storm-damaged timber and any tree close to a road, building or power line should be handled by a qualified professional. A larger chainsaw does not make a complicated tree safer to fell. Should you buy a 14, 16 or 18-inch chainsaw? For many UK gardens, the decision comes down to these three common bar lengths. Bar length Choose it when Main trade-off 14 inches You prune, clear small trees or cut modest logs Light and easy to handle, but limited on wider timber 16 inches You want one saw for general garden work and firewood A useful balance of reach, weight and control 18 inches You regularly cut larger firewood or medium timber More capacity, but extra weight and more power required If two approved sizes can handle your timber, the shorter bar is usually easier to control. Pick the longer approved option when you genuinely need the extra reach on a regular basis. Why should you avoid buying a chainsaw that is too large? An oversized petrol chainsaw can make ordinary garden work slower and more tiring. Extra engine capacity and bar length increase weight, and fatigue can reduce control. A longer bar also gives you more guide-bar nose to keep clear of branches and other obstructions. Choose a larger petrol chainsaw only when the timber size, wood hardness and frequency of use justify it. New users should prioritise balance, manageable weight and clear access to controls over maximum CC. What else should you compare besides CC and bar length? Engine size and bar length narrow down the choice, but they should not be the only checks. Compare: Power output in kilowatts, especially when comparing saws with similar CC ratings Weight without fuel and cutting equipment The manufacturer’s minimum and maximum approved bar lengths Chain pitch, gauge and availability of replacement chains Anti-vibration features and handle comfort Side-access or tool-free chain tensioning Starting assistance and engine management features Access to servicing, spare parts and technical advice The best petrol chainsaw should feel balanced before you even start the engine. If the dry weight feels awkward, fuel and cutting equipment will not improve it. How can you choose the right petrol chainsaw in five steps? Measure the diameter of the branches, logs or trunks you cut most often. Decide how frequently you will use the saw and how long each session lasts. Choose a CC range that suits the timber size and whether it is softwood or hardwood. Select an approved bar length that covers your normal cuts without adding unnecessary weight. Compare model weight, safety features, parts support and servicing before ordering. If your usual work sits between two sizes, choose based on frequency. Occasional larger timber may be better handled by hiring equipment or a professional. Regular heavy cutting can justify the more powerful saw. Petrol chainsaw safety and training A correctly sized chainsaw is still a high-risk tool. The Health and Safety Executive’s chainsaw guidance covers training, maintenance, personal protective equipment and safe working practices for professional use. Its guidance explains that kickback can occur when the chain at the guide-bar nose strikes an object. Before using a petrol chainsaw: Read the operator’s manual for the exact model Wear chainsaw trousers, chainsaw boots, gloves, hearing protection and suitable head, eye and face protection Check the chain brake, chain tension, lubrication and sharpness Keep other people outside the working area Do not cut above shoulder height or use a chainsaw one-handed Get recognised training before felling trees or doing chainsaw work for employment Frequently asked questions about petrol chainsaw sizes Is a 30cc chainsaw big enough for home use? Yes. A 30cc petrol chainsaw with a 12 to 14-inch bar is enough for pruning, small logs, light firewood and routine garden clearance. Choose a larger model if you regularly cut thick hardwood or medium trees. Is a 40cc chainsaw suitable for firewood? Yes. A 40cc petrol chainsaw with a 14 to 16-inch bar is a good general choice for domestic firewood. Check that the typical log diameter fits the usable bar length and reduce the workload if the saw repeatedly slows under load. What can a 50cc chainsaw cut? A 50cc petrol chainsaw commonly runs a 16 to 20-inch bar and suits regular firewood, thicker hardwood and small to medium trees. Exact capability depends on the model, chain, timber and operator experience. Can you put a longer bar on any petrol chainsaw? No. Fit only a bar length, mount, pitch and gauge approved for the exact chainsaw. A bar that physically attaches may still exceed the engine’s power or oiling capacity. Check the manual or ask a dealer. Can a chainsaw cut timber wider than its bar? An experienced operator may cut wider timber using more than one cut, but this needs skill and careful planning. Beginners should choose a bar that covers the intended cut from one side or call a trained professional for large timber. Is a shorter chainsaw bar safer? A shorter bar is generally lighter and easier to manoeuvre, but no chainsaw size is automatically safe. Correct technique, training, maintenance, PPE and awareness of the guide-bar nose all remain necessary. What chainsaw size is best for a beginner? A beginner should usually look at a well-balanced 30cc to 40cc petrol chainsaw with a 12 to 16-inch bar for ground-level domestic work. The final choice should match the timber and the manufacturer’s guidance, not just the user’s experience. Do you need a licence to use a chainsaw in the UK? There is no general chainsaw licence for private use on your own property. Employers must make sure chainsaw users receive adequate training and are competent for the work. Formal training is also strongly advised for felling, aerial work and any difficult or high-risk job. Find the right petrol chainsaw at MowShop The right petrol chainsaw matches the timber you cut, the time you spend cutting and your level of experience. For general home use, start around 30cc to 45cc with a 12 to 16-inch bar. For regular firewood or medium timber, compare 45cc to 60cc models with 16 to 20-inch bars. Browse MowShop’s chainsaw range to compare domestic and professional models from STIHL, Husqvarna and ECHO. If you are unsure, contact the MowShop team with your usual timber diameter and workload so they can help you narrow down the right size. MowShop supplies domestic and professional garden machinery from its Allscott depot in Telford. Technical recommendations should be checked against the current manufacturer specification for each model.
