Avg Shipping Cost, Japan Post

Metrics type: Key Metrics • Category: Cost & Efficiency

At a glance

Mean carriage charge per Japan Post shipment over the trailing 30 days, compared against the prior 30-day period. It is the blended cost across every service the merchant uses (Yu-Pack domestic, Yu-Pack Cool, EMS, Letter Pack), so it moves when the service mix shifts, when parcels get heavier, when destination zones change, or when Japan Post reprices. The alert fires when the blended cost rises 10 percent or more versus the prior period, which is the despatch team’s signal that something in the cost base has moved.


What it tracks	`SUM(shipment_charge) ÷ COUNT(shipments)` over the rolling 30-day window, with the same calculation run on the prior 30 days for the period-over-period comparison. Charge is the billed carriage amount including fuel and zone surcharges, in JPY (¥).
Data source	Per-shipment charge fields returned by the Japan Post shipping and billing APIs, reconciled against the manifest. Each shipment contributes one charge keyed to its service code, weight band, and destination prefecture or country zone.
Currency	Japanese yen (¥). For merchants billing in another currency, the card reads the JPY charge at source; conversion is a display choice, not part of the calculation.
Service scope	Blended across all connected Japan Post services. Yu-Pack and Yu-Pack Cool are domestic; EMS is international; Letter Pack is flat-rate domestic. Because the rates differ by an order of magnitude (a Letter Pack Light is ¥370, an EMS to Europe can exceed ¥6,000), the blended average is dominated by the service mix.
Return-leg inclusion	Outbound only. Return-to-sender carriage is tracked on Returned to Sender; including it here would inflate the average with a different cost profile.
Surcharges	Fuel surcharge, remote-area (離島) surcharge, and oversize Yu-Pack dimension surcharges are included in the per-shipment charge. Customs duties and consumption tax collected from the recipient are not carriage and are excluded.
Time window	`30D vsP` (rolling 30 days, period-over-period).
Alert trigger	`+10% vsP` (blended cost per shipment is 10 percent or more above the prior 30-day period).
Roles	owner, operations

Calculation

Calculated automatically from your Japan Post data. See the At a glance summary above for what the metric tracks and the worked example below for a typical reading.

Worked example

The same Osaka DTC apparel and homeware brand, around 3,200 outbound parcels per week. Reading taken at 09:30 JST on 12 Apr 26 for the trailing 30 days (13 Mar 26 to 11 Apr 26), compared against the prior 30 days (11 Feb 26 to 12 Mar 26).

Service	Shipments (30D)	Total charge (¥)	Avg per shipment (¥)	Prior-period avg (¥)
Yu-Pack domestic	9,180	7,160,400	780	765
Yu-Pack Cool (chilled)	1,420	1,789,200	1,260	1,255
EMS (international)	1,640	8,479,200	5,170	4,420
Letter Pack	1,480	547,600	370	370
All Japan Post (this card)	13,720	17,976,400	¥1,310	¥1,180

The card reads ¥1,310 per shipment, up 11.0 percent on the prior period’s ¥1,180. The +10% vsP alert is tripped. Five things to notice:

The blended number moved but most services barely did. Yu-Pack domestic is up ¥15 (about 2 percent), Yu-Pack Cool and Letter Pack are flat. The 11 percent jump is almost entirely the EMS line, which rose from ¥4,420 to ¥5,170 (up 17 percent). The blended average is a mix metric: it can alert even when no single service got materially more expensive.
Two things drive the EMS rise: mix and rate. EMS volume grew from 1,210 to 1,640 shipments (international demand up after a spring campaign), and the per-shipment EMS charge rose. Pull Yu-Pack Cost by Prefecture Zone and Cost by Zone to separate “we shipped more expensive lanes” from “the lanes themselves cost more”.
Check the EMS fuel surcharge. Japan Post revises the EMS fuel surcharge periodically; a mid-period revision shows up here as a step change in the EMS per-shipment charge with no change in weight or zone. If the surcharge moved, this is a rate event, not a mix event, and the action is to reprice international checkout shipping, not to re-route.
The blended average hides margin risk. At ¥1,310 average across 13,720 parcels, monthly carriage is ¥18.0m. An 11 percent rise is roughly ¥1.78m of additional monthly cost. If international checkout shipping was set to a fixed ¥1,500 flat fee, the EMS rise has quietly eroded the contribution margin on every overseas order; revisit the checkout shipping table.
Watch the outliers separately. A handful of very heavy or remote-zone EMS parcels can drag the average up on their own. High-Cost Shipment Outliers isolates them; if three or four ¥12,000 oversize EMS parcels landed in the period, strip them out before concluding the base rate has changed.

Sibling cards merchants should reference together

Average shipping cost is a blended outcome. Pair it with the cards that break the blend apart:

Card	Why pair it with Avg Shipping Cost	What the combination tells you
Cost by Zone	Splits the blended average by destination zone.	Tells you whether the rise is a lane-mix shift (you shipped further) or a per-lane rate change (the lane got dearer).
Yu-Pack Cost by Prefecture Zone	Domestic-only zone breakdown for the dominant service.	Isolates Honshu / Hokkaido / Okinawa / 離島 (remote island) cost bands within Yu-Pack, the biggest volume line.
Cost Per Shipment Trend	The same metric as a time series rather than a single comparison.	Shows whether the 11 percent rise is a one-period spike or a sustained climb; a step change points to a rate revision, a ramp points to mix drift.
High-Cost Shipment Outliers	Surfaces the parcels dragging the mean up.	Confirms whether a few oversize or remote-zone parcels are distorting the average before you act on the headline.
Shipments by Service	The service-mix view.	EMS at ¥5,170 versus Letter Pack at ¥370 means the blended average is mostly a mix number; this card shows the mix that drives it.
Yu-Pack Cost vs Sibling Carriers per Zone	Benchmarks Japan Post against alternative carriers per zone.	Tells you whether a rising lane is worth re-routing to Sagawa / Yamato or another carrier, or whether everyone has repriced.
Cross-connector: `shopify.refund_rate`	Downstream margin link.	If you absorb the cost rise rather than reprice, contribution margin falls silently; if you pass it on, watch for checkout abandonment.

Reconciling against the source

Where to look in Japan Post’s own tooling: Japan Post Business Customer Portal then the Billing / Invoice section (ご請求 / 料金明細). The monthly invoice is the authoritative cost record; it lists each consignment’s billed charge by service code, weight band, and destination zone. For account customers, the Shipping Management (発送管理) view also exposes per-shipment charges before the invoice is finalised. Charge and scan timestamps in these views are in carrier-local time (JST). The closest like-for-like view is all services, last 30 days, outbound only, divided by the consignment count. Japan Post’s invoice totals the charge; divide by the line count to get the per-shipment average the card shows. Why our number may legitimately differ from Japan Post’s invoice:

Reason	Direction	Why
Estimated vs billed charge	Either	The card reads the charge known at manifest time; the final invoice can adjust for re-weighs, dimension corrections, or remote-area surcharges applied after collection. Re-weighed parcels reconcile up; the invoice is the final word.
Billing-cycle vs rolling window	Either	Japan Post invoices on a calendar billing cycle; the card uses a rolling 30-day window. A rate revision mid-cycle lands in different buckets. Match the date ranges before comparing.
Time zone (JST vs UTC)	Boundary days	Charges are dated in JST on the invoice; Vortex IQ stores in UTC and converts back. Boundary-day shipments can fall in different days, though the 30-day total agrees within about 1 percent.
Return-leg exclusion	Ours lower if RTS-heavy	The card is outbound only; the invoice may include return carriage. A merchant with a high return-to-sender ratio sees a different denominator.
Tracking and billing ingestion lag	Ours can lag	Charge data flows through Japan Post’s billing feed on a delay; very recent shipments may not yet carry a confirmed charge and are excluded until they do.

Cross-connector reconciliation:

Card	Expected relationship	Causes of legitimate divergence
`shopify.shipping_charged_to_customer`	Cost versus what you charged the buyer	Cost is Japan Post’s charge; revenue is your checkout shipping fee. The gap is your shipping margin (or subsidy). A rising cost with a fixed checkout fee narrows it.
`shippo.avg_label_cost`	Aggregator-reported cost when Shippo or EasyPost sits in front	Aggregators report the rate they were quoted, which can differ from Japan Post’s final invoice after re-weigh. Reconcile the aggregator dashboard against the underlying Japan Post invoice, not against each other.

Known limitations / merchant FAQs

The card alerted at +10 percent but no service got 10 percent dearer. How? Mix. The blended average rises when a more expensive service takes a larger share of volume, even if every individual rate is flat. A spring international campaign that lifts EMS volume from 9 percent to 12 percent of parcels will raise the blend on its own, because EMS is many times the cost of a domestic Yu-Pack. Read Shipments by Service alongside this card to tell mix from rate. How do I tell a rate change from a mix change? Look at the shape. A rate revision is a step: the per-shipment charge for one service jumps on a specific date and stays there. A mix shift is a ramp: the blend drifts as volume re-weights. Cost Per Shipment Trend shows the shape; Cost by Zone confirms whether specific lanes repriced. Why does my Japan Post invoice show a higher total than the card? Three usual reasons. (1) The invoice includes re-weigh and dimension corrections applied after collection; the card reads the manifest-time charge. (2) The invoice may include return-leg carriage, which the card excludes. (3) Billing-cycle versus rolling-window boundaries put a rate revision in a different bucket. Match the date range and the outbound-only filter, then expect agreement within a percent or two, with the invoice as the final authority. Does the average include consumption tax or customs duties? No. The card tracks carriage only: base rate plus fuel, remote-area, and oversize surcharges. Japanese consumption tax on the carriage itself is handled per your account terms; customs duties and import taxes are collected from the recipient on EMS parcels and are not carriage, so they never appear here. A few huge EMS parcels are dragging the average up. Can I exclude them? The headline blends everything, but High-Cost Shipment Outliers isolates the long tail. Use it to confirm whether the rise is broad (the base rate moved) or narrow (three oversize parcels). If it is narrow, the action is packaging or service selection for those SKUs, not a checkout reprice. Should I re-route to another carrier when this alerts? Only after checking Yu-Pack Cost vs Sibling Carriers per Zone. If Japan Post repriced a lane but Sagawa, Yamato, or an aggregator like EasyPost or Shippo did not, re-routing that lane saves money. If the whole market repriced (a common fuel-surcharge event), re-routing buys little and the real lever is the checkout shipping table. Why is the window 30 days and period-over-period rather than a fixed target? Shipping cost has no universal target: a chilled-food brand running mostly Yu-Pack Cool will sit far above an apparel brand on Letter Pack, and both can be perfectly healthy. The meaningful question is “did my own cost base move”, so the card compares each merchant against their own prior period rather than a benchmark. Tune the threshold in the Alert Rules tab if your seasonality makes 10 percent too tight.

Tracked live in Vortex IQ Nerve Centre

Avg Shipping Cost is one of hundreds of KPI pulses Vortex IQ tracks across Japan Post and 70+ other ecommerce connectors. Nerve Centre runs the detection layer; Vortex Mind investigates the cause when something moves; Ask Viq lets you interrogate any number in plain English. Start for free or book a demo to see this metric running on your own data.

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At a glance

Calculation

Worked example

Sibling cards merchants should reference together

Reconciling against the source

Known limitations / merchant FAQs

Tracked live in Vortex IQ Nerve Centre

​At a glance

​Calculation

​Worked example

​Sibling cards merchants should reference together

​Reconciling against the source

​Known limitations / merchant FAQs

​Tracked live in Vortex IQ Nerve Centre

At a glance

Calculation

Worked example

Sibling cards merchants should reference together

Reconciling against the source

Known limitations / merchant FAQs

Tracked live in Vortex IQ Nerve Centre