Plastic Bottle Cap Size Chart
Measure across the threads of the bottle neck and enter it to find the closure size, such as 24-410, with the neck finish chart.
How to use the plastic bottle cap size chart
- Measure the bottle neck across the outside of the threads. Enter that number in Thread diameter (T), in mm or in.
- Open Thread turns and choose 1 turn (400), 1.5 turns (410) or 2 turns (415). If you cannot count the turns, keep I don’t know.
- Read the Closure size (neck finish) row first. This is the closest listed size, such as 24-410.
- Check Nominal diameter (mm), T in the chart and E in the chart (neck below thread). For sizes 18 to 28, the rows Thread depth, (T − E) ÷ 2 and Your reading compared with the chart also appear.
- Read any warning. It tells you when no listed size is close enough, when your reading is outside the chart tolerance, or when a size has no T and E data.
- Open How it was calculated to see each step worked out with your own numbers.
To see how a result looks before you measure, press one of the example buttons: 23.6 mm, 1.5 turns, 27.4 mm, 1 turn, 1.5 in or 19.6 mm.
When you have a result, Copy result copies it, and Copy link makes a link that keeps all your inputs. Print / save as PDF prints your inputs, results, steps and the date. Reset clears the form. Results are estimates, so compare them with your bottle before you buy.
What does 24-410 mean on a bottle cap?
The first number is the nominal thread diameter in millimetres, so 24 means the thread is about 24 mm across. The second number is the thread style: 410 means the thread makes 1.5 turns around the neck. A cap and a neck need to share both numbers, so a 24-410 cap is matched to a 24-410 neck.
How do I measure a bottle neck size?
Measure across the outside of the threads, not the plain neck below the threads. Enter the reading as T. Measure more than once, because a small error can change which size the finder picks: sizes 18, 20 and 22 are only about 2 mm apart in the chart. If a result looks wrong, measure again across the thread crests.
What is the difference between 400 and 410 caps?
The number after the dash describes how many turns the thread makes. A 400 thread makes one turn, a 410 thread makes 1.5 turns, and a 415 thread makes two. Suppliers say the two numbers must match, so a 400 cap does not fit a 410 neck of the same diameter. One supplier page lists 400 as 1.5 turns, so count the turns on your own bottle before you rely on a style.
What cap size fits a 28mm bottle?
A 28 mm reading is matched to size 28. The chart lists 28-410 with T at 1.076 in (27.33 mm) and E at 0.982 in (24.94 mm). The thread style comes from your count of the turns. Entering 27.4 mm with 1 turn gives 28-400, which is 0.07 mm above the chart T, while 1.5 turns points you to 28-410.
What are T and E dimensions on a bottle neck?
T is the outside diameter across the threads. E is the outside diameter of the neck below the threads. The thread depth is (T − E) ÷ 2, which is how far the thread stands out from the neck. For 24-410, T is 0.930 in (23.62 mm) and E is 0.846 in (21.49 mm), so the depth is 0.042 in (1.07 mm). The chart also lists H, the finish height, and S, the distance from the top to the first thread. For 24-410, H is 0.636 in and S is 0.046 in.
Sources
Checked October 2026:
- Evergreen Resources, Glass Neck Finish Dimensions: T, E, H and S values with tolerances for the 410 profile in sizes 18 to 28, and 400 = 1 turn, 410 = 1.5 turns, 415 = 2 turns
- Indiana Bottle Co., cap and neck finishes: the first number is the diameter in mm and the second is the thread style, with the same turn counts
- U.S. Plastic Corp., caps catalogue p. 55: meaning of T, E, H, S and I, thread depth = (E and T difference) ÷ 2, and the list of common closure sizes
- No public thread-pitch table was found, so none is shown; check the bottle maker’s finish drawing for exact threads
For estimation; verify critical designs against the applicable standard.
Worked examples
| Input | Result |
|---|---|
| T = 23.6 mm, thread turns: I don't know | 24-400 / 24-410 / 24-415 |
| T = 27.4 mm, thread turns: 1.5 | 28-410 |
| T = 0.77 in, thread turns: 1 | 20-400 |
| T = 38 mm, thread turns: 1 | 38-400 |
Calculated by the tool above with these values.
Frequently asked questions
Is the calculator free, and is anything I type uploaded?
Yes, it is free, runs in your browser, and needs no sign-up. Nothing you type is uploaded.
Why does the finder show no match for 25.5 mm?
A reading of 25.5 mm is more than 1 mm away from both 24 (23.62 mm) and 28 (27.33 mm), so no listed size is close enough. The tool shows a warning instead of guessing a size.
Does the chart apply to plastic bottles?
The dimension table is for glass finishes defined by GPI. Plastic finishes use the same number style, but a plastic drawing was not found, so treat the values as a guide and check the cap against your bottle. Sizes outside 18 to 28 (13, 15, 30, 33, 38 and up to 120) show only the nominal match, with no T and E values.
Why does the result list 24-400, 24-410 and 24-415?
When you choose I don’t know for thread turns, the finder lists all three styles for the nearest size, because the diameter alone cannot tell them apart. Choose the turn count once you have counted it on the neck to get one answer.
What does the tolerance warning mean?
It means your reading is outside the chart tolerance, which is 0.010 in (about 0.25 mm) for sizes 18 to 24 and 0.012 to 0.013 in for size 28. Measure the thread again before you trust the match.
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