4 Inch Vs 5 Inch Angle Grinders

This article will explain each and every difference between the entry level Angle Grinders. Comparison based on handling, ease of use and versatility. If you are the first time buyer, then I would suggest you to follow with this article on Angle Grinder Buying Guide.

In the above mentioned article, I have explained everything to get you started with Angle Grinders. What I missed in that article is what I have mentioned below. If you are from US, you need to focus more on 4.5/5″ discs as they are widely used instead of 4″. For India, 4″ should be more focused. Every market is different.

4 inch Angle Grinder (AG4) 4.5 / 5 inch Angle Grinder (AG5)
The cheapest angle grinder to buy. Entry level 5 inch models are similarly priced to top end 4 inch grinders.
Most versatile, also available in mini sizes in order to operate in single hand. 4 inch large grinders are also available. Choice is yours to buy either large or compact. Single hand use models have less capacity. What actually matters is motor size. More the power you need, grinder becomes larger in size and cannot be operated in single hand.
Ranges from 650 watts to 1000 watts. Ranges from 750 watts to 1400 watts.
Operates at high RPM. Slightly lower RPM than 4 inch model.
Spindle size is 10mm (M10 Nut). Spindle size is 14mm (M14 Nut).
Max Size that can be used is 100mm or 4 inches with Guard mounted. You can also use 5 inch Velcro/ backing pad attachment discs. Make sure you buy M10 sized backing pad. Here is where this grinder excels. Since the Nut size is same for 7 & 9 inch models, uptil 9 inch discs can be used. Safety guard does not support big sizes, and need you to manage yourself getting a new guard to comply with bigger size discs. If your grinder is underpowered, stick to 5 inch. Remember, not to exceed Permitted disc RPM, you can use an SCR Controlled Rectifier in order to reduce Grinder Speed.
Supportable inner disc diameter is 16mm. Supportable inner disc diameter is 22.23mm.
Most of the Marble cutter blades, Concrete Cutter blades, Tile Cutting Diamond Discs, Wood cutting blades having 20mm Arbor diameter can be easily used with 4 inch angle grinders. You can safely use them even with Safety guard, since their maximum size is 4 inches. Though they come with 20mm inner dia, 20-16 Step down rings are available. You cannot use, 4 inch Masonry discs with 20mm arbor. You need the disc inner dia to be exact 22.23mm. Marble Cutting Discs, Concrete Cutting and Wood Cutters are available. Finding them is quite hard. Even some discs come with 25.4mm (1 inch) arbor size. Still you have an option of 25.4-22.23mm Step down rings.
Prices for 4 inch discs very basic. Expensive because they don’t sell very often. This increases cost too. (Depends on Country to Country)
For Cutting Wheels, it is always better to go for a bigger disc. Larger the disc, larger will be its cutting depth into the metal. 4 inch cut off discs will get emptied just within a couple of cuts. This makes you frustrated to change discs every now and then. Nowadays diamond discs are available to cut metals instead of abrasive discs. This saves time, but comes at a reasonable cost. Here too, discs get emptied. But not as fast as 4 inch ones. Also 5 inch discs bite the metal even deeper. Like discussed above, larger discs can also be used to overcome this problem. But grinder is supposed to have enough energy to utilize larger discs. Never use larger discs without appropriate Safety Guards.
Soft Start Feature is 99% not available in 4 inch Angle Grinders. Soft Start is a feature where the grinder increases speed gradually by reducing the initial torque. This is not only a safety feature but also most necessary feature for those who have/ had wrist ligament injuries. Grinders are slightly on the expensive side, like the Bosch GWS 14-125.

What I didn’t mention above , is weight of Angle Grinders. More the power rating, more the weight. The power rating mentioned on the grinder spec sheet is its electricity consumption and not its motor output. There are still more things to consider when making your purchase like, switch types, handle positions, etc which I have already mentioned in the above article. If you haven’t read that article yet, please have a look at now, Click this link. Angle Grinder Buying Guide.

If you want to learn more on the types of discs available for Angle Grinders, please have a look on this article on Angle Grinder Wheel Types.

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