# Calculate Japan Post Postage and Yu-Pack Fees

Japan Post fees depend on mail dimensions, weight, service options, and parcel origin. This skill calculates supported charges from dated tables and identifies missing information.

## Install

```bash
npx skillstore add tahodev/yubin-fee
```

## Metadata

- Status: approved
- Slug: tahodev-yubin-fee
- Skillstore revision: r1
- Version status: missing
- Tree hash: a5f525274efb800d019aff102f90e3bb2f9b4c4802e513477cd000a306566485
- Author: tahodev
- GitHub username: tahodev
- License: MIT
- Repository: https://github.com/tahodev/kurashi-skill/tree/09cb7f9eac85f0c85633cce08328a1a57854a94f/yubin-fee
- Ref: 7f17813fb6af1acc7d8fd3fb5f05480f5be52783
- Supported tools: Claude, Codex, Claude Code
- Audit status: complete
- Agent install advisory: allowed
- Manual install advisory: allowed
- Artifact signature: available
- Audit attestation: unavailable
- Human verification: not\_verified
- Risk factors: external\_commands, network, filesystem
- Quality score: 77
- Quality tier: bronze
- Public page: https://skillstore.pages.dev/skills/tahodev-yubin-fee
- Manifest: https://skillstore.pages.dev/api/skills/tahodev-yubin-fee/manifest

## Capabilities

- Classify standard and nonstandard letters by dimensions and weight, then calculate their base postage.
- Look up postcard, mini-letter, Letter Pack, and Smart Letter prices and size or weight limits.
- Add express, registered-mail, and delivery-record surcharges while checking supported option combinations.
- Calculate Tokyo-origin Yu-Pack fares by parcel size and destination region, including the listed heavy-parcel surcharge.
- Calculate stamp combinations that cover the full postage without understating the required charge.
- Ask for missing measurements and include the applicable rate revision or verification date in answers.

## Use Cases

- Estimate Letter Postage: Check an envelope against size and weight limits, then calculate the required postage and a suitable stamp combination.
- Budget Parcel Shipping: Estimate Tokyo-origin Yu-Pack costs from package measurements and destination regions before quoting shipping to customers.
- Price Recorded Office Mail: Compare supported registered-mail and delivery-record charges, including compatible express options, for outgoing documents.

## Prompt Templates

### Check Basic Letter Postage

```
My domestic envelope is 20 cm by 10 cm by 0.5 cm and weighs 30 g. Calculate postage and state the rate date.
```

### Compare Mail Options

```
My domestic envelope measures 30 by 20 by 2 cm and weighs 100 g. Compare express, simplified registered, and delivery-record charges, including valid combinations.
```

### Estimate a Tokyo Parcel

```
My parcel ships from Tokyo to Osaka, measures 30 by 25 by 20 cm, and weighs 5 kg. Calculate undiscounted Yu-Pack postage.
```

### Prepare a Batch Postage Budget

```
For [mail items with dimensions, weights, destinations, and options], calculate individual charges, stamp combinations, and the batch total. Flag missing details and unsupported services.
```

## Limitations

- Built-in Yu-Pack fares cover Tokyo departures only; other origins require the official calculator or an origin-specific table.
- Yu-Mail base fares, international mail, and options outside the listed services are not supported.
- Rates are embedded snapshots, not live data; future revisions require official verification and table updates.
- Accurate estimates require packed dimensions, weight, and relevant locations; the skill does not purchase postage or arrange shipping.

## Best Practices

- Provide measurements and weight after packing, plus parcel origin and destination prefectures.
- Specify required service options and check compatibility before adding their charges.
- Keep the rate basis date in each estimate and verify official rates when revisions may apply.

## Anti Patterns

- Applying Tokyo-origin Yu-Pack prices to parcels sent from another prefecture.
- Combining registered mail with delivery-record service, which the skill explicitly disallows.
- Guessing dimensions, weights, unsupported fees, or future rates to produce a complete-looking estimate.

## Security Audit

- Audited at: 2026-10-13T04:31:16.197\+00:00
- Summary: All ten static findings are false positives in this readable, documentation-only skill. URLs cite official Japan Post sources; backticks mark metadata, and the parent-directory path links documentation rather than performing filesystem operations. No evidence found of prompt injection, secret access, data exfiltration, or executable commands.

## Stats

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- Downloads: 0
- Favorites: 0
- Popularity score: 0