Guide · Measuring and buying
How to measure your rack's uprights, holes and spacing
The three numbers that decide attachment fit, how to measure each one on your own rack, and how makers print sizes in inches and millimeters.
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Short answer
Measure three numbers on your own rack: the upright's outer size, the hole diameter and the center-to-center hole spacing. Add the pin size your rack's own attachments use and, for parts that span the bay, the inside depth. Write each down in the unit you measured, and treat any conversion as a calculation, never as proof of fit.
The numbers to record
| Number | What it is | Why it matters |
|---|---|---|
| Upright outer size | The outside width of the tube, both pairs of faces | The attachment's mounting plate must wrap or sit on it |
| Hole diameter | The width of the opening in the upright | The attachment's pin must pass through it |
| Hole spacing | Center to center, between neighboring holes | Parts with a second pin or lock tab need it to match |
| Pin size | The pin your rack maker's own J-cups use | Many makers sell attachments by pin class |
| Inside depth | Front upright to rear upright, inside faces | Straps and pipes that span the bay |
Upright outer size
Use a caliper if you have one, or a steel rule held square across the tube. Measure the outside faces, not the inside of a hole. Then turn 90 degrees and measure the other pair of faces. On a square tube the two match; on a rectangular tube, such as 2x3 in, they do not, and you should note which face carries the holes.
Measure at a clean spot away from welds and labels.
Hole diameter
Measure the opening itself, across its widest point, not the pin that came with the rack. The hole and the pin are two different numbers; our hole diameter vs pin diameter guide explains why. If the hole is a keyhole (a large opening joined to a smaller one), measure both parts.
Hole spacing
Measure from the center of one hole to the center of a hole several holes away, then divide by the number of gaps. One gap alone is too short to read accurately.
Do this in more than one zone. Many racks change pattern along the upright. Titan, for example, says T-2 vertical holes are 2 in on center, although some sections between holes measure 1 in.[1] Note where the pattern changes and which zone you plan to mount the attachment in. Our guide to Westside, 2 in and metric spacing covers the common patterns.
Converting between inches and millimeters
One inch is exactly 25.4 mm.[2] Every conversion below is a calculation from that definition:
| Nominal size | Calculated |
|---|---|
| 2 in | 50.8 mm[2] |
| 3 in | 76.2 mm[2] |
| 60 mm | about 2.362 in[2] |
A converted number tells you nothing about clearance. It never makes a metric part "fit" an imperial rack.
How makers print sizes
Makers print rounded labels, and they round differently:
- Bells of Steel says its racks use either 2.3 x 2.3 in (60 x 60 mm) or 3 x 3 in (76.2 x 76.2 mm) tubing.[3]
- Force USA lists MyRack uprights as 2.4 in square (60 mm).[4]
- Powertec says its Premium J-hooks fit Powertec racks with 2 3/8 x 2 3/8 in uprights.[5]
- Rogue lists the SML-2 uprights as 3 x 3 in, 11-gauge steel.[6]
So "2.3 in" and "2.4 in" can both describe 60 mm tubing. Compare your own measurement with the maker's label, not one label with another.
When the maker publishes two numbers
Write both down. Titan gives the T-2 hole size as 26 mm in its spec table and as 1 in holes in its description.[7] Titan's support answers call the T-2 12-gauge steel, while its comparison page lists 14-gauge.[1] Titan also says the lowest and highest T-2 hole heights are not currently available, though the same support page gives 1593.5 mm for the top J-hook hole of the T2RACK83_BK.[1]
Does paint or powder coat change the size? It can add a little, but no maker we found publishes coated sizes or fit tolerances. Record what you measure.
Your measuring sheet
| Field | Your rack |
|---|---|
| Maker, model, year | |
| Upright, face with holes | |
| Upright, side face | |
| Hole diameter (and keyhole parts) | |
| Spacing in your mounting zone | |
| Spacing elsewhere | |
| Pin size of the maker's J-cups | |
| Inside depth |
With these numbers you can read any attachment listing. Some makers sell one product in several sizes and ask you to pick the variant:
Picks that fit1 product
Choose the variant that matches your upright (2x2, 2x3 or 3x3 in). For 1 in holes, choose a converter version and confirm the converter is in the package; the NC versions take 5/8 in holes only.
More on choosing
On Amazon, check that Ships from / Sold by is Amazon.com or Synergee.
Choose Synergee if your rack is not on any maker's named list
Synergee J-Cups, pair (2x2, 2x3 or 3x3; 5/8 in or 1 in converter)
Next
Questions
Which faces of the upright do I measure?
Measure the outside of the tube across two opposite faces, then turn 90 degrees and measure the other pair. On a rectangular tube such as 2x3 in the two numbers differ, so note which face carries the holes.
Is my rack 2x3 in or 50x75 mm?
Measure it and compare with the maker's published size. 2 in works out to 50.8 mm and 3 in to 76.2 mm, so a nominal 2x3 in tube is not the same size as a 50x75 mm tube.[2]
How do I measure hole spacing accurately?
Measure from the center of one hole to the center of a hole several holes away, then divide by the number of gaps. Do it in more than one zone, because spacing can change along the upright; Titan says some T-2 sections measure 1 in although the holes are 2 in on center.[1]
Does paint or powder coat change the size?
It can add a little, but no maker we found publishes coated sizes. Record what you measure and what the maker publishes, and let the attachment maker decide whether your rack is on its host list.
Is 16 mm the same as 5/8 in?
No. 5/8 in works out to 15.875 mm. Treat the two as different numbers even when a maker prints them side by side.[2]