I am new to electronics, and I inherited a breadboard from my grandfather. I could fit 2.54 mm headers into it (as shown below):

Old Breadboard - 40 Pin Header

I recently got a new breadboard, but the holes seem to be closer to each other, and the headers won't fit (shown below, on the left it looks like it lines up, but as it gets further to the right the pins are further and further from the hole):

New Breadboard - 40 Pin Header

I also got a compatible/clone Arduino Nano, which plugs just fine into my new (narrower) breadboard, but not my older (wider) breadboard (pictures below):

Old Breadboard - Compatible Nano New Breadboard - Compatible Nano

I measured the pitch and found that the old breadboard has a 2.54 mm pitch, but the new breadboard seems closer to 2.45 mm.

Is there more than 1 standard for breadboard and header pitch, or if not, what's going on???


  • 1
    \$\begingroup\$ all nominally 0.1" breadboards should be 2.54 mm pitch. However, some cheap ones may be made incorrectly. The new one you have should still work with a short run of pins. You just have to buy better quality. \$\endgroup\$
    – Neil_UK
    Commented Dec 26, 2020 at 12:54
  • \$\begingroup\$ I did think it was a quality issue as well UNTIL, to my surprise, my Compatible Nano's headers fit perfectly into this new breadboard! \$\endgroup\$
    – ktstuff
    Commented Dec 26, 2020 at 13:43
  • 1
    \$\begingroup\$ Measure the distance over 50 rows or so. \$\endgroup\$ Commented Dec 26, 2020 at 15:33
  • \$\begingroup\$ It's one of the realities with US based suppliers using inches and the rest of the world using metric. As Chris Stratton says measure the distance over 50 rows. \$\endgroup\$ Commented Dec 26, 2020 at 15:48
  • \$\begingroup\$ Is that a genuine Nano from the Arduino store? Or a clone? If from Ali Baba, it may have a 2.50 mm / 0.098 pitch header. 2.50 mm is A standard pitch, but is not the standard pitch for Arduino nano, nor for breadboards as far as I know. It is more likely, that your measurement of 2.45 mm is incorrect, and the actual pitch is 2.50 mm., but I could be mistaken. \$\endgroup\$ Commented Dec 29, 2021 at 23:31

2 Answers 2


The "new" breadboard you got is junk. It is not "incompatible in pitch". It's incompatible with the notion of quality. It has poor dimensional control - throw it away.

The standard for solderless breadboards is only one: 2.54mm center-to-center.

Anything else "close but not quite" goes into the trash can. Forget about it. It's not worth dealing with such junk. You won't ever get your life spent on it back.

When measuring dimensions, it's good to use a caliper. There do exist 2.00mm square pin headers, and those would be rather misleading if you accidentally used one as a reference. Even cheap calipers will do a fine job if you measure distances over 20-30 holes.

I usually buy breadboards made by 3M. They can be found cheaper on eBay, as long as they are in the original packaging, and locally (US, Canada or Europe, NOT China). Never had a problem with them. Yes, they cost more than the usual cheap stuff, but you get what you pay for. Compared to 3M products, the cheap stuff is not worth the aggravation - especially if your goal is to get something actually done, and not fighting basic parts used for your prototyping.

I have little experience with cheap ones other than the observation that they don't last, the plating wears off quickly if you actually use them heavily, the connection points are not formed for the wires (parallel edges vs. facing C-shaped edges), and the first problem they will cause in your prototyping will undo any and all savings instantly.


2.54mm (or 100mil) spacing is pretty common, but there do exist other variant spacings for breadboards and perfboards (1.27mm, 5.08mm, etc). I believe the Arduino Nano is designed with 2.54mm spacing, but it probably fits on your 2.45mm breadboard since the pins might be flexing on it.

  • \$\begingroup\$ Thank you for your reply. Do these different pitch standards have names? When I order components for my projects, I want to be able to make sure they fit my breadboard. I now have some items that fit my old breadboard and some that fit my new breadboard. It might get messy if I can't standardise. \$\endgroup\$
    – ktstuff
    Commented Dec 26, 2020 at 11:28

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