Weights and Measures Verification: Which Instruments Must Be Stamped

This page is the weights and measures operating file: which instruments must be stamped before they may decide what one party pays another. It is not a calibration manual, and it is not a product-standards file.

• When short measure is deliberate: acting against counterfeits
• Who licenses the truck under the load: LATRA, TASAC and who regulates what
• Where the crop on the scale grows: agricultural land access
• Fare and charter meters: tourist transport approvals

As at 14 September 2026. Confirm classes, pattern approvals and fees with the Ministry of Industry and Trade; this file rests on Cap. 340 and its Regulations, and on Zanzibar’s own 2020 statute.

The Agency stamps, and “use for trade” is the trigger

Verification is run by an executive agency of the industry ministry. The Chief Inspector of Weights and Measures approves patterns and licenses repairers; inspectors test, stamp and seal equipment on site, and may enter trading premises unannounced.

What pulls equipment into scope is use for trade: the reading decides what one party pays the other. A gym scale is outside it; the identical scale at a weigh-and-pay scrap yard is inside it. A pharmacy balance, a milk can, a textile metre rule and a sixty-tonne weighbridge answer to one Act.

Verification is not calibration. A laboratory certificate records what an instrument read on a day; an inspector applies the maximum permissible error for the accuracy class the approved pattern carries, then fixes a uniform mark and a seal that cannot be disturbed without leaving evidence. The Agency’s own working standards are re-verified yearly and its secondary standards every two years: the chain that makes a verdict hold in a dispute.

Which instruments carry a stamp

Utility meters sit apart: a water or electricity dispute runs first through the utility and EWURA under the Energy and Water Utilities Regulatory Authority Act, Cap. 414. Taximeters fall in wherever a fare is computed from measured distance.

The Mainland and Zanzibar stamp separately

This is not a Union function. Cap. 340 reaches Mainland Tanzania only. Zanzibar runs a parallel regime under the Zanzibar Weights and Measures Agency Act, No. 6 of 2020, with its own inspectors and fee schedule.

So a scale tested in Dar es Salaam and shipped to a shop in Stone Town is unverified for island purposes until island inspectors have tested it themselves. A distributor trading on both sides budgets two verification rounds a year and keeps two sets of certificates: the same split that puts BRELA and BPRA, and TRA and ZRA, on separate lines of the corporate file.

Screen the trade before you buy the instrument

Ownership first. GN No. 487A of 2025 carries the schedule of activities reserved for citizens, and small-scale retail and several produce-trading activities sit on that side of the line. An inspector will stamp equipment in a shop its owner is not permitted to hold, and the licensing officer will still close it.

Sector licence second. The instrument follows the licence, never the reverse. A dispenser presupposes an EWURA retail licence; a mineral buying balance a dealer or broker licence from the Mining Commission; a warehouse scale on crops in the warehouse receipt system an operator licence from the Tanzania Warehouse Licensing Board. Ordering equipment before that decision strands a container in a store room for a season.

Pattern approval, imports, and the repair that kills a stamp

Equipment can only be verified if its pattern is approved. Approval attaches to the model, not the unit, so an unapproved model cannot be stamped at any price. A pallet of cheap electronic scales bought on unit price, with no approval and no service agent behind it, is scrap the day it lands. Clearing goods in TANCIS moves them out of the yard and confers nothing on their legality for trade.

Repair is regulated in its own right. Anyone who repairs, adjusts or installs trade equipment needs a repairer’s licence, and working without one is an offence under the Regulations. Any intervention breaking a seal ends the verification on the spot, after a load-cell replacement, a pump service, a board swap. Constructing a storage tank whose contents are measured for trade carries its own licence, which a depot that pours the foundation first discovers late.

The verification sequence

1. Settle the licences: business licence under the Business Licensing Act, Cap. 208, the sector licence, the ownership screen.
2. Confirm the pattern: take the approval reference from the supplier in writing before paying a deposit.
3. Install, then apply: apply in the region where the equipment will stand; a weighbridge needs its foundation cured and approaches level.
4. Pay on a control number: fees follow the published schedule by class and capacity, settled through GePG. Nothing is handed to an inspector.
5. Meet the inspector at the instrument: testing happens on site, and the equipment must be clean, level, powered and empty.
6. Take the mark and the paper: mark and seal onto the instrument, certificate into the file, copy to the premises.
7. Diarise the next round: the lapse date belongs in the compliance calendar beside the licence renewal.

What the file carries to the inspector

The Agency is testing equipment, not auditing a company, so the pack is short.

• An application listing every instrument by type, make, model, serial number, accuracy class and maximum capacity.
• The pattern approval reference for each model on that list.
• The supplier’s invoice or delivery note, with the manufacturer’s data plate still legible.
• The previous certificate on a re-verification, plus the repairer’s job card wherever a seal has been broken since.
• Business licence, TIN, and the sector licence: EWURA, Mining Commission, warehouse or market authority as the case may be.
• For a weighbridge: site layout, foundation completion record and load-cell serial numbers.

Keep certificates where the equipment is. A folder at a Dar es Salaam head office does nothing for a branch manager in Songea with the inspector already on the floor.

Pre-packed goods are sold by net content

Quantity law does not stop at the instrument. Pre-packed goods must declare net content (the product, not the wrapping) in metric units, within the tolerance the Regulations allow. Charging a customer for packaging is an offence in itself.

The Metric System Enforcement Order made under the Act removed imperial units from trade, so a price quoted per debe, per sado or per tin rests on nothing enforceable. Nor does the lumbesa habit of over-filling a maize sack beyond its declared mass; directives standardising the 100-kilogram bag exist because that practice moves value quietly away from the grower.

Illustrative arithmetic: what 1.2% costs a buying post

A cashew buying post receives deliveries from growers across one season. Illustrative arithmetic, not a quotation.

• Volume received over the season: 900,000 kg.
• Scale reading 1.2% light against the seller: 900,000 × 0.012 = 10,800 kg.
• Assumed grower price of TZS 2,300 per kg: 10,800 × 2,300 = TZS 24,840,000 of crop taken in and never paid for.

That is not margin. It is restitution owed to identifiable growers, on top of the offence of using a false or unjust instrument, for which the Act provides a fine and imprisonment on the live schedule. The books suffer too: the service levy charged on turnover by the local authority under the Local Government Finance Act, Cap. 290 at 0.3% is computed on figures the weighbridge tickets contradict.

Run the error the other way and the loss is the trader’s. The same 1.2% on a dispenser over-delivering against 180,000 litres a month gives away 2,160 litres monthly and 25,920 litres across a year, on product that already carried VAT at the standard rate of 18% under the Value Added Tax Act, Cap. 148. Confirm the live schedule on tra.go.tz.

Where this file stalls

• The pattern was never approved, the equipment cannot be stamped, and the supplier no longer answers.
• A weighbridge was relocated or its deck resurfaced after stamping, and nobody presented it again.
• Equipment is rated far below the load routinely placed on it; a reading outside the class range is not a reading.
• A deliberate short-measure complaint is answered with a re-test. Knowingly selling short is a consumer-protection and criminal matter, not a metrology one.
• Cash is offered to an inspector, converting a testing fee into a file for the Prevention and Combating of Corruption Bureau.
• Zatra’s professional fee is buried inside the government fee line. It belongs on its own. See pricing.

Mandate-holders this file does not replace

The Agency owns quantity. It owns neither quality, nor price, nor product safety, and confusing those desks costs weeks.

• Tanzania Bureau of Standards: product conformity under the Standards Act, Cap. 130, and food and cosmetics since the Finance Act, 2019 moved those categories from the former TFDA. Standards decide whether a product is fit; verification decides whether the amount is right.
• EWURA: petroleum and gas retail licensing and regulated pricing under Cap. 414. A verified pump inside an unlicensed station is still an unlicensed station.
• Fair Competition Commission: consumer protection and misleading conduct under the Fair Competition Act, Cap. 285, where deliberate short measure ends up.
• Mining Commission: dealer, broker and mineral market licensing. The balance gets verified; the trade gets licensed.
• TANROADS: axle-load control under the East African Community Vehicle Load Control Act, 2016. A load-control weighbridge enforces road limits, settles no price, and passing one is not verification.

Zatra prepares the applications, builds the instrument schedule and coordinates the visit. It does not stamp equipment, issue licences, or offer assurance that anything will pass.

What to confirm before you act

• That the model quoted holds a current pattern approval, in writing from the supplier.
• Accuracy class and maximum capacity against the heaviest and lightest load you will trade.
• Which agency holds the mandate where the equipment will physically stand.
• The re-verification cycle for that class, and the date the present mark lapses.
• Who your licensed repairer is: decided before a seal breaks, not afterwards.