Scales used in trade are marked with where they may be used
#0018 Work & industry
Fact rank
S
Primary sources (the Tokyo and Niigata weights-and-measures offices, a scale maker) state the restriction on where scales may be used and how it is marked, and an industry handbook explains the 16 zones of the old law. S as expected
Wow rank
S
Common knowledge in the trade, but almost unknown to the public: scales have an area where they may be used
Usefulness
B
Useful for businesses buying a scale, but few everyday uses for others
Verification: Supported by evidence
Rule check: an article whose "why" cannot be written with sources is capped at fact rank B.
AI verification reports the evidence it found; it does not guarantee that a claim is true.
Scales used for trade or certification are adjusted to the gravity where they are used, and are marked with the range of gravitational acceleration they may be used in (for example 9.798–9.801 m/s²). Using one outside that range gives wrong readings, so it may not be used there. Under the old Measurement Act, Japan was divided into 16 zones by gravity.
Why
(No sourced explanation yet.)Evidence
Primary Notice from the Tokyo Metropolitan weights-and-measures office (attached to a Tokyo Medical Association notice, 2025). Scales have a designated area of use. Gravitational acceleration in Tokyo is 9.798 m/s², and a scale may be used if its marking includes this value link
Primary FAQ of the Niigata Prefecture weights-and-measures office. The place of use is shown as a range or value of gravitational acceleration, a place name, or a zone number (old standard); using a scale marked for a different place causes wrong measurements link
Primary Technical note from a scale maker (A&D). Verified scales are marked with the area where they are used and may not be used beyond it; models with a built-in weight are among the exceptions link
Secondary Sample chapter of a scale handbook (Nikkan Kogyo Shimbun, chapter 1). Under the old Measurement Act Japan was divided into 16 zones by gravitational acceleration (in steps of 0.001 m/s²); under the current law the range of gravitational acceleration is marked on the scale link
Notes and limits
This applies to "specified measuring instruments" used for trade or certification; household bathroom and kitchen scales are not covered. Models with a built-in weight that recalibrate on site, and some coarse accuracy classes, are not restricted by area (maker's document). According to the industry handbook, a 1.0000 kg weight on the same electronic scale reads 0.9996 kg in Kagoshima and 1.0007 kg in Sapporo.
Derivations
Derived from: 体重計の数字は緯度が高いほど大きく出る
Derived facts: —