Is 150 × 1220 mm the same as 6 × 48 in?

Your sander’s manual asks for a 6 × 48 in belt, and the shop sells 150 × 1220 mm. Or your band saw takes a 1140 mm blade, and every listing says 44-7/8 in. This guide shows how far apart those figures really are, why both exist, and what to check before you order.

Do the conversion first.

One inch is exactly 25.4 mm, so an inch size converts without any rounding:

• 6 × 48 in is 152.4 × 1219.2 mm. Compared with 150 × 1220 mm, the metric belt is 2.4 mm narrower and 0.8 mm longer.
• 4 × 24 in is 101.6 × 609.6 mm. Compared with 100 × 610 mm, the metric belt is 1.6 mm narrower and 0.4 mm longer.
• 44-7/8 in is 1139.825 mm. Compared with 1140 mm, the difference is less than a fifth of a millimetre.

The unit converter does this for any size, including fractions such as 93-1/2.

Why one size carries two labels.

Many common sanding belt and bandsaw blade sizes are inch sizes. Where tools are sold in metric, makers round them to whole millimetres, and they don’t all round the same way. In the manufacturer documents behind our catalogue, belts within a few millimetres of 6 × 48 in are given as 150 × 1220, 152 × 1220, 150 × 1219 and 152 × 1219 mm.

Manufacturers do it themselves, sometimes on the same page. Makita’s Canadian page for the 9404 belt sander gives its belt as “4" x 24" (100 mm x 610 mm)”. The UK page says 100 x 610 mm and the US page says 4" x 24". DEWALT’s North American manual for the DCS374 portable band saw asks for “44-7/8" (1140 mm) long blades”; the UK manual gives 1140 mm. On BenchRefill each of these is a separate record for its country, so the Makita 9404 appears under both sizes.

What the difference means in practice.

Length. A belt or blade is tensioned by moving one drum or wheel, so a machine takes up small differences in length. That is how a maker can print 1220 mm for a 48 in belt. The tensioner covers only a limited range, though: the next length up or down is a different size, not a substitute.

Width. Width is where the rounding is largest: up to 2.4 mm on a 6 in belt. Belts run on drums and a platen made for their width, and blades run in guides set for a width range. Whether your machine accepts a millimetre or two either side of the listed size is a question for its manual or its manufacturer.

The product label. Many belts and blades are sold with both figures on the label, such as “150 × 1220 mm (6 × 48 in)”. When only one is given, compare it with the size documented for your machine, not with a conversion you rounded yourself.

How BenchRefill shows them.

We record every size exactly as the manufacturer printed it, with the exact conversion next to it, and we never merge two sizes because they are close. A size page lists only machines documented for that exact figure; close sizes appear separately under “Nearby sizes”. We don’t say that a belt labelled in one system fits a machine documented in the other.

Inch and metric pairs in the catalogue.

These sizes sit within a few millimetres of each other. Each count is the number of machines documented for that exact figure today. Open a size to see them.

Differences compare the metric figure with the inch size converted exactly.