Rack Hole Spacing Explained
Hole spacing sets the available adjustment positions. Hole diameter, pin diameter and upright size answer different questions.
By IRONINDEX · How we research
Introduction
Rack hole spacing is the distance from the centre of one hole to the centre of the next along an upright. It sets how finely you can adjust the height of J-cups and safeties: closer spacing gives more positions to choose from.
Spacing doesn't describe how wide each hole is, and it doesn't prove an attachment will fit. Those are separate measurements, and it helps to keep them apart when comparing racks or buying new J-cups.
What to consider
- 01
Spacing
The centre-to-centre distance between holes. Some racks change spacing part-way up the upright, so each zone you'll use is worth checking.
- 02
Hole diameter
The width across each hole. It's a different figure from the diameter of an attachment's pin, and the two are rarely identical.
- 03
Hole position
Where the holes sit on the upright matters as well. Matching spacing alone doesn't mean a bracket's pins will line up.
- 04
Front and side faces
Some racks have holes on more than one face of each upright. Attachments that mount on the side need the side holes checked too.
Buying advice
Why some racks have two spacings
Some racks use closer holes where precise height matters most. Mirafit specifies 1-inch spacing through the M3's bench-press area and 2-inch spacing elsewhere, which it calls West side spacing; in metric, those intervals are 25.4 mm and 50.8 mm. Decathlon's Power Rack 900 instead uses 3.5 cm intervals for its bar-rest holes.Source: Mirafit M3 rack: dimensions and installation notesSource: Decathlon Power Rack 900 support and specifications
Closer holes give more positions within that zone. Whether that helps depends on where your bench, J-cups and safeties need to sit, so it's worth checking that the close-spaced section covers the heights you actually use.
Measuring spacing accurately
Spacing is measured from the same point on two neighbouring holes, such as the top edge of one to the top edge of the next. Measuring the gap between their nearest edges leaves out one hole's width and gives a figure that is too small.
Measuring across several holes and dividing gives a more accurate reading. Six holes in a row contain five gaps, so the total is divided by five, not six. The measurement needs to stay within one spacing zone.
Hole numbers stamped on a rack help you repeat a setting, but they aren't a standard height scale between brands. A drawing from the brand gives the actual dimensions.
Hole size and pin size are different figures
Mirafit's M3 Roller J-Cups use a 16 mm pin and are specified for the M3's 17 mm holes. That pairing is documented by the brand. It doesn't give a general rule for how much smaller a pin from another brand should be.Source: Mirafit M3 Roller J-Cups: pin and rack dimensions
Attachments that use more than one hole need every pin position to line up, as well as the bracket's shape around the upright. A single pin sliding into one hole doesn't settle that.
- Spacing between hole centres in the zone you'll use.
- Hole diameter, recorded separately from the attachment's pin diameter.
- Holes on the side faces, if an attachment mounts there.
- The brand's list of attachments approved for that rack.
Conclusion
Hole spacing tells you how finely a rack adjusts. Hole diameter, pin diameter and hole position tell you whether an attachment can be fitted. A matching spacing figure on two products is a useful start, but it isn't a compatibility statement.
For anything you plan to pin or bolt onto a rack, the brand's list of approved attachments for that exact model is the most reliable answer.
Sources
Primary references used for factual claims in this guide. Product specifications apply to the named model and version.
- Mirafit M3 rack: dimensions and installation notes
Mirafit. Accessed 21 Sept 2026.
- Decathlon Power Rack 900 support and specifications
Decathlon. Accessed 21 Sept 2026.
- Mirafit M3 Roller J-Cups: pin and rack dimensions
Mirafit. Accessed 21 Sept 2026.