Angle Grinder Disc Sizes: 100 to 230 mm, Max RPM, and What Fits What
Disc diameter sets the machine, the arbor and the maximum RPM — it is a safety system, not a preference. The 100–230 mm size chart, the 80 m/s rule behind the printed limits, and the job-to-disc table.
Every resin disc carries two numbers that matter more than its price: diameter and maximum RPM. They are not independent — the RPM limit exists to keep the disc rim under 80 metres per second, the design ceiling for bonded abrasives. Bigger disc, same rim speed, lower RPM. Which is why a disc must never go on a smaller, faster machine than it was made for, and why the size chart below is really a safety chart wearing a catalogue’s clothes.
The size chart
| Disc Ø | Inch name | Max RPM | Arbor | Typical machine & market |
|---|---|---|---|---|
| 100 mm | 4" | 15,300 | 16.0 mm | Compact grinders — dominant in India & SE Asia |
| 115 mm | 4½" | 13,300 | 22.23 mm | One-hand grinders — Middle East, Europe, Africa |
| 125 mm | 5" | 12,200 | 22.23 mm | One-hand, more reach — the global all-rounder |
| 150 mm | 6" | 10,200 | 22.23 mm | Between classes; fabrication shops |
| 180 mm | 7" | 8,500 | 22.23 mm | Two-hand grinders — heavy fabrication |
| 230 mm | 9" | 6,600 | 22.23 mm | Two-hand — structural steel, masonry cutting |
Two details in that table decide whole purchase orders. First, the 100 mm class runs a 16 mm arbor, not 22.23 — a container of 4" discs with the wrong bore fits nothing in the Indian market it was bought for. Second, the max RPM printed on the disc must be equal to or higher than the grinder’s no-load speed. A 115 mm disc on a 100 mm machine spins inside its limit; a 100 mm disc forced onto nothing smaller exists — the guard stops it, and the guard is right.
Diameter also tracks machine class. The 100 mm grinders that dominate India and the Philippines run 750–850 W and one hand; a 230 mm machine wants 2 kW-plus, both hands and a brace. And the RPM marking rule covers every wheel that fits the spindle — flap discs, wire wheels and diamond blades carry the same max-RPM print, and it binds the same way.
Thickness: cutting is thin, grinding is thick
- 1.0–1.6 mm flat (Type 41): cut-off work in sheet, tube, stainless. Thin kerf means less heat, less burr, less metal wasted — a 1.0 mm disc cuts stainless with barely a temper mark.
- 2.5–3.2 mm: general cutting where the disc gets levered slightly by hand-held work. More forgiving, slower.
- 6.0–6.4 mm depressed-centre (Type 27): grinding only — welds, chamfers, fettling. Built to load the face, never the edge.
- The rule that never bends: a cutting disc never grinds on its side, a grinding disc never cuts on its edge. The safety logic is in the cut-off wheel checks.
Job-to-disc table
| Job | Disc | Notes |
|---|---|---|
| Cut mild steel sheet / tube | 1.0–1.6 mm cut-off, Type 41 | Thin = cool and fast |
| Cut stainless (INOX) | ≤1.6 mm INOX-rated cut-off | Fe/S/Cl-free bond — no rust bloom on the cut |
| Grind welds, bevel plate | 6 mm Type 27 grinding wheel | Work at 25–35° to the surface |
| Blend and finish welds | Flap disc, 40→60→80 grit | See the flap disc grit guide |
| Cut tile / porcelain | Continuous-rim diamond | No hammer, no twist — see diamond blade types |
| Cut concrete / stone | Segmented diamond | Dust extraction or wet |
| Sand / strip paint | Hook-and-loop sanding disc on backing pad | Grits 60–120 for stripping |
From our range
Industrial 4.5" (115mm) Ultra-Thin 1.0mm Cut-Off Wheel for INOX – OEM
115 mm × 1.0 mm INOX cut-off — the fastest-moving abrasive SKU in most export orders.
From our range
Industrial 4.5" (115mm) Depressed Center Grinding Wheel for Metal – OEM
115 mm depressed-centre grinding wheel — the Type 27 workhorse for weld dressing.
The date stamp nobody reads
Resin-bonded discs have a use-by date — normally three years from manufacture, stamped on the metal arbor ring. The phenolic bond absorbs moisture and weakens with age, and an expired disc fails the same way an abused one does: at full speed. For distributors this is a stock-rotation rule, not trivia — first in, first out, and never buy a "bargain" pallet without reading the rings. Cracked, dropped or damp-stored discs go in the bin; the safety checks list the full pre-flight.
For the counter and the container
Get the mix right by market: 100 × 16 mm bore for India, Pakistan and the Philippines; 115 and 125 × 22.23 for the Middle East and Africa; thin INOX cut-offs outselling everything else in both. Cutting discs are consumed, not owned — a fabrication shop burns boxes per week, which makes cutting and grinding discs the steadiest repeat line in the catalogue. We load mixed-size, mixed-type pallets in the same container as drills and blades so the reorder is one shipment, not three.
Products mentioned in this guide
Cut-Off Wheels
Industrial 4.5" (115mm) Resin Cut-Off Wheel for Stainless Steel – OEM
Cut-Off Wheels
Industrial 4.5" (115mm) Ultra-Thin 1.0mm Cut-Off Wheel for INOX – OEM
Grinding Wheels
Industrial 4.5" (115mm) Depressed Center Grinding Wheel for Metal – OEM
Flap Discs & Sanding
