What's the Difference Between 400 and 410 Threads?
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Short answer: the diameter is identical — a 28/400 and a 28/410 are both 28 mm across. The difference is thread height. A 400 finish is short and takes about one full turn to close. A 410 finish is taller and takes roughly one and a half turns. Put a 400 cap on a 410 neck and it bottoms out early and sits loose.
The three finishes you'll actually meet
| Finish | Turns to close | Where you see it |
|---|---|---|
| 400 | ~1 | The household standard — soap bottles, jugs, most glass |
| 410 | ~1.5 | Taller neck — some lotion and cosmetic bottles |
| 415 | ~2 | Tall narrow bottles, some pharmacy packaging |
All three exist in the same diameters. That is exactly why the numbers are written as a pair: 33/400 is 33 mm across with a 400 thread.
How to tell which one you have
You don't need a gauge. Screw your existing cap on and count.
- About one full turn and it's tight → 400
- A turn and a half → 410
- Two turns → 415
Then measure the diameter across the outside of the rim to get the first number. A ruler is enough: 28 mm ≈ 1–1/8″, 33 mm ≈ 1–5/16″, 38 mm ≈ 1–1/2″.
All our pumps are 400 finish — the household standard. Free US shipping over $15, ships in one business day from Lakewood, NJ.
• 28/400 — from $10.00
• 33/400 — from $14.00
• 38/400 — from $17.00
Will a 400 cap work on a 410 neck?
It will thread on, and that is what catches people out. It engages the first thread, feels like it is tightening, then stops with the cap sitting proud of the shoulder. It won't seal, and with a pump it will wobble and eventually cross-thread the neck.
The reverse — a 410 cap on a 400 neck — spins past the threads and never grips at all.
Where the numbers come from
They're SPI (Society of the Plastics Industry) standards, which is why a 33/400 pump from one manufacturer fits a 33/400 bottle from another. It is one of the few genuinely universal standards in packaging, and it is the reason a replacement pump is worth buying rather than replacing a whole bottle.
Not sure what you've got?
Photograph the bottle opening with a ruler laid across it and email support@kitchentoolz.com. We'll identify it for you.