Note: This article covers shipping rate settings for Japan Post, which is specific to merchants shipping within Japan. The information below will not be directly relevant if you are not selling in the Japanese market.
When using Japan Post for a Shopify store, the following points tend to cause the most trouble when designing shipping rates:
- How to manage the 3cm thickness limit
- How to reproduce Yu-Pack rates, which change based on size
While some services offer a flat nationwide rate, there are plenty of cases where the shipping cost jumps unexpectedly the moment your packaging slightly exceeds the conditions.
In particular, Shopify's standard features cannot automatically judge thickness or set shipping rates based on size, so you need a design that's built around Japan Post's delivery rules.
This article organizes Japan Post's main delivery services, then explains how to correctly reproduce shipping rates in Shopify and the operational precautions needed to avoid losing money.
※ This information is based on details as of January 2026.
Japan Post's basic services
Image source: Japan Post official site
Japan Post's delivery services are characterized by a network that covers all of Japan, along with a diverse lineup ranging from post-drop-off services to large parcels.
In particular, services like Click Post, Yu-Packet, and Letter Pack are available at a flat nationwide rate, which is a major advantage for keeping Shopify store shipping rate design simple.
When using Japan Post on Shopify, it's important to understand the "weight limit rules" and "thickness limits," which differ from Yamato Transport and Sagawa Express.
Below, we'll explain the following main services commonly used in Shopify operations.
- Yu-Pack / Heavy Yu-Pack
- Chilled Yu-Pack
- Letter Pack
- Yu-Packet
- Click Post
Yu-Pack / Heavy Yu-Pack
"Yu-Pack" is Japan Post's most standard parcel delivery service. It covers size 60 through size 170, and is widely used as the main shipping method for Shopify stores.
Size is determined by the sum of the three dimensions: length + width + height.
Example: 30cm (length) × 40cm (width) × 20cm (height) → Size 100 (80cm or more, less than 120cm)
A key point when using Yu-Pack is the weight bracket. Japan Post's weight brackets are simple — there are only two: the standard "Yu-Pack" for up to 25kg, and "Heavy Yu-Pack" for over 25kg up to 30kg.
Yamato Transport and Sagawa Express, on the other hand, compare "size" and "weight" and apply whichever bracket is larger. Because of this, when shipping small but heavy items, choosing Japan Post tends to keep shipping costs significantly lower than the other carriers.
Yu-Pack rates
Yu-Pack rates are determined by the following two conditions:
- Distance from the origin to the destination
- Size of the parcel
Weight does not affect the rate as long as it is 25kg or less.
<Reference rates: example rates for shipping from Tokyo to Osaka>
| Size bracket | Yu-Pack rate (tax included) |
|---|---|
| Size 60 | ¥990 |
| Size 80 | ¥1,310 |
| Size 100 | ¥1,620 |
| Size 120 | ¥1,940 |
| Size 140 | ¥2,300 |
| Size 160 | ¥2,610 |
| Size 170 | ¥3,750 |
If you want to check the rate from your own location to a specific area, check the Japan Post official page.
Heavy Yu-Pack rates
Heavy Yu-Pack adds a flat +¥560 to the Yu-Pack rate.
Yu-Pack / Heavy Yu-Pack restrictions and Shopify operational notes
- Size: within 170cm total for the three dimensions
- Weight: up to 25kg for Yu-Pack, 25kg to 30kg for Heavy Yu-Pack (parcels over 30kg cannot be accepted)
Within 25kg, the rate is determined by size alone. However, Shopify's standard features cannot set shipping rates based on size. That's why we recommend setting a "deemed weight" on products according to their size bracket.
※ For detailed conditions and the latest rates, check the Yu-Pack official page and Heavy Yu-Pack official page.
Chilled Yu-Pack
Chilled Yu-Pack is a service that ships items in a refrigerated temperature range (0℃ to 5℃). It's suitable for shipping fresh food, sweets, and similar items.
Note that it does not support the frozen temperature range.
Chilled Yu-Pack rates
A chilled surcharge based on size is added to the standard Yu-Pack base rate.
| Size bracket | Chilled surcharge (tax included) |
|---|---|
| Size 60 | +¥225 |
| Size 80 | +¥360 |
| Size 100 | +¥675 |
| Size 120 | +¥675 |
| Size 140 | +¥1,330 |
| Size 150 | +¥2,100 |
Chilled Yu-Pack restrictions and Shopify operational notes
- Size: up to size 150
- Weight: up to 25kg
- Pre-cooling is required
- Frozen temperature range is not supported
- Items that cannot be laid on their side must be 50cm or less in height
You must use a post office counter that handles Chilled Yu-Pack to drop off a shipment.
Also, Shopify's standard features cannot automatically add a "chilled surcharge" on top of the standard Yu-Pack shipping rate.
For this reason, when using Chilled Yu-Pack, you must always create a dedicated shipping profile and set the shipping rate to already include the chilled surcharge.
※ For detailed conditions and the latest rates, check the Chilled Yu-Pack official page.
Letter Pack
Letter Pack lets you purchase a dedicated envelope and ship a parcel at a flat nationwide rate. There are two types: "Letter Pack Plus," delivered in person, and "Letter Pack Light," delivered to the mailbox.
Image source: Japan Post official site
Since it's dropped in a mailbox, it can be shipped 365 days a year and is delivered daily, including weekends and holidays in principle. On Shopify, it's often used for shipping small, lightweight items such as T-shirts, supplements, and accessories.
Letter Pack rates
It's a flat nationwide rate, with the shipping fee included in the price of the envelope.
| Service name | Rate (tax included) | Delivery method |
|---|---|---|
| Letter Pack Plus | ¥600 | In-person delivery |
| Letter Pack Light | ¥430 | Mailbox drop-off |
Letter Pack restrictions and Shopify operational notes
- Size: A4 file size (34cm × 24.8cm)
- Weight: up to 4kg
- Thickness: Light is within 3cm. Plus has no limit (as long as it fits in the envelope)
Since it can also carry correspondence, it's suitable for shops that want to enclose delivery notes or message cards.
Because Letter Pack is shipped using Japan Post's dedicated envelopes, Shopify's shipping settings cannot perform automatic shipping-rate calculations or automatic detection of multiple envelope counts based on "Letter Pack" as a premise.
For this reason, it's common practice on Shopify to simply set a "Letter-Pack-equivalent shipping rate," while the shop itself judges at shipping time whether the item actually fits in the envelope.
※ For detailed conditions and the latest rates, check the Letter Pack official page.
Yu-Packet
Yu-Packet is a mailbox-drop-off delivery service where the shipping rate is split into three tiers depending on thickness. Because tracking is included, managing delivery status on Shopify is also smooth.
It can be shipped 365 days a year and is delivered daily regardless of weekends and holidays. It generally arrives the day after or two days after shipping.
However, this "rate tier by thickness" cannot be automatically judged by Shopify's standard features. As a result, the following kinds of trouble tend to occur on Shopify:
- The shipping rate was set for "1cm (¥250)," but the actual packaging comes out to 2cm, and the shop ends up covering the difference
- Multiple items purchased together push the thickness over 3cm, meaning it should really be shipped via Yu-Pack, but the Yu-Packet rate is applied at checkout anyway
For this reason, without deciding on operational rules in advance, you can easily end up losing money on shipping.
Yu-Packet rates
It's a flat nationwide rate, determined by thickness.
| Thickness bracket | Rate (tax included) |
|---|---|
| Within 1cm | ¥250 |
| Within 2cm | ¥310 |
| Within 3cm | ¥360 |
Yu-Packet restrictions and Shopify operational notes
- Size: within 60cm total for the three dimensions, longest side within 34cm
- Thickness: within 3cm
- Weight: up to 1kg
Shipping requires a dedicated "Yu-Packet label," which can be obtained at a post office counter.
Image source: Japan Post official site
※ For detailed conditions and the latest rates, check the Yu-Packet official page.
Click Post
Click Post lets you pay the shipping fee and create an address label online, then drop the parcel in a mailbox. It's a flat nationwide rate and one of Japan Post's most affordable services, so it's often used by Shopify stores handling low-priced products.
Click Post rates
- Rate: flat nationwide ¥185 (tax included)
Click Post restrictions and Shopify operational notes
- Size: length 14–34cm, width 9–25cm, thickness within 3cm
- Weight: up to 1kg
To use Click Post, you need one of the following:
- Obtain a Yahoo! JAPAN ID and register to use Yahoo! Wallet (credit card payment)
- Obtain an Amazon account and register to use Amazon Pay (credit card payment)
※ For detailed conditions and the latest rates, check the Click Post official page
Key points when setting Japan Post shipping rates on Shopify
If your Shopify store uses Japan Post as its main shipping method, keeping the following points in mind will help ensure smooth operation.
Set Yu-Pack using deemed weight
Shopify's standard features cannot set shipping rates based on "size." For this reason, we recommend setting shipping rates on a "weight basis." However, with Yu-Pack, weight up to 25kg doesn't affect the rate — the rate is determined by size alone.
So by setting a "deemed weight" corresponding to the size bracket, you can bring the rate closer to Yu-Pack's official rate table.
Example settings
- Size-60 product → register as 1kg
- Size-80 product → register as 2kg
- Size-100 product → register as 3kg
This lets you automatically calculate a rate close to Yu-Pack's official rate table, based on the total weight in the cart.
Order limits to stay within "3cm thickness"
For small items, shipping methods that require "within 3cm thickness" — such as Click Post, Yu-Packet, and Letter Pack Light — are used frequently. However, since Shopify cannot automatically judge thickness, multiple items purchased together may actually exceed 3cm when packed, unexpectedly requiring a switch to Yu-Pack.
An effective countermeasure is to set an order limit such as "maximum ○ items per order," capped at the quantity that fits within 3cm thickness.
For order limits, the Shopify app "RuffRuff Order Limits" is recommended.
Set a dedicated shipping rate for Chilled Yu-Pack
Since Chilled Yu-Pack adds a size-based chilled surcharge on top of the standard Yu-Pack rate, a dedicated shipping rate setting is required. If this setting is missed, the shop ends up covering the surcharge.
In practice, it's common to manage shipping profiles separately for room-temperature and refrigerated products. However, note that when profiles are split, Shopify's specification is such that shipping is "combined as separate shipments" if a normal item is purchased at the same time.
To avoid confusion at checkout, be sure to state on product pages and in your shipping policy that "items in different temperature ranges will be shipped separately, and separate shipping fees may apply."
Common notes for mailbox-drop-off services
Mailbox-drop-off services such as Click Post, Yu-Packet, and Letter Pack Light share the following common rules:
- Correspondence (shinsho) such as delivery notes or invoices cannot be enclosed
- Even if a delivery incident occurs, compensation is generally not provided
If you need to ship important documents or products that require compensation coverage, choose a service with compensation, such as Yu-Pack.
Trouble that can occur without order limits
In practice, even if the shipping rate design is correct, "order content" can sometimes require unexpected handling.
Specifically, the following kinds of trouble can occur:
Losses from increased parcel counts when using a flat nationwide rate
When shipping rates are set as "flat nationwide," a large order may require a size increase or shipment split into multiple parcels, resulting in actual costs that exceed the set shipping rate, which the shop must absorb.
Exceeding the weight limit (30kg)
Orders that exceed Heavy Yu-Pack's weight limit cannot be accepted, resulting in extra administrative work such as split shipments or re-billing.
Use an app to apply order limits
A mechanism that limits orders at the ordering stage is effective for preventing this kind of trouble.
By using the Shopify app "RuffRuff Order Limits," you can control checkout based on conditions such as weight or quantity.
For example, you can prevent customers from proceeding to checkout if the total weight in the cart exceeds Click Post's limit (1kg) or Yu-Pack's limit (30kg).
You can also display a message such as "This exceeds the limit for a single parcel. Please reduce the quantity or split your order," which makes the reason clear to the customer as well.
Controlling orders on the system side like this helps prevent shipping-rate losses and shipment-related trouble before they happen.
For specific setup steps, please also refer to the following article.
Setting up Japan Post correctly on your Shopify store
Japan Post offers a wide range of flat-nationwide-rate, mailbox-drop-off services, making it a carrier that can simplify shipping rate design even for remote islands and outlying areas.
Also, since Yu-Pack rates don't differ by weight up to 25kg, it's a feature that makes it easier to keep costs down even for heavier products. On the other hand, because of clear rules such as the 3cm thickness limit and weight caps, a Shopify design built around order limits and shipping rules is essential.
Start by organizing the size, thickness, and weight of your own products, and try building a shipping pattern that matches Japan Post's rules.
