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2026-09
Seed Phrase Storage Capsule: Designing for 12- and 24-Word Backups
A seed phrase storage capsule should specify more than its supported word count. For product designers and OEM buyers, usable capacity depends on the recording method, letter inventory, word separation, and available holder length.
Define the Recording Format
For the English BIP-39 word list, the first four letters uniquely identify each word; shorter words should be recorded in full. This principle should not be assumed to apply to every recovery system or language.(github.com)
Under a four-position-per-word layout:
- A 12-word seed phrase backup requires 48 character positions.
- A 24-word seed phrase backup requires 96 character positions.
A design must also explain how shorter words, blank positions, and word boundaries are represented. Character capacity alone does not establish usability.
Calculate the Stack Before Sizing the Cover
Consider an illustrative design, not a specification for the pictured product: 96 tiles, each 0.30 mm thick, produce a nominal stack length of 28.80 mm, excluding separators and retention hardware.
If each tile has a thickness tolerance of ±0.01 mm, the arithmetic worst-case stack variation is ±0.96 mm. Holder length and retaining-clip position must accommodate the defined tolerance budget.
For a custom metal seed phrase backup, request a drawing that identifies usable stack length, tile thickness, word indexing, and retention allowance. Also verify the supplied letter distribution: space for 96 characters does not guarantee enough copies of every required letter.
About NKEYTO
NKEYTO is the international brand of Shenzhen Xintu Precision Hardware Co., Ltd., a precision metal manufacturing supplier based in Shenzhen, China.
We provide one-stop precision metal manufacturing services, including chemical etching, precision laser cutting, stamping, CNC machining, electroplating, and other customized surface treatments. Our capabilities support the development and production of precision metal components for industries such as semiconductors, electronics, optics, medical devices, and industrial applications.
With engineering support and flexible manufacturing capabilities, we help customers develop customized metal parts from prototypes to small and medium-volume production.
For technical evaluation or quotation, please feel free to contact:
Luna
Head of International Trade & Pre-Sales Technical Consultant
Email: luna@nkeyto.com
WhatsApp: +1 213 221 9094
Phone / WeChat: +86 135 5470 8126
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Shenzhen Nkeyto Precision Hardware Co., Ltd. is a factory specializing in precision hardware processing, committed to providing customers with high-quality products and services.We look forward to working with you.
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E-mail: luna@nkeyto.com
Tel: +1 213-221-9094
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