Direct answer
For qualifying packaged goods, choose either a minimum system or an average system and document how quantity is controlled. Under the average system, the batch average must not be below nominal quantity, only a limited proportion may exceed the tolerable negative error, and no pack may be short by more than twice that error.
Why this matters
The legal control system affects filler targets, sampling, checkweigher settings, record keeping and giveaway. It should be defined before using one tolerance as a machine acceptance figure.
Decision table
| Nominal quantity | TNE rule | Production implication |
|---|---|---|
| 5–50 g/ml | 9% of nominal | Small packs need proportionally tighter control |
| 50–100 g/ml | 4.5 g/ml | Fixed tolerance band |
| 100–200 g/ml | 4.5% of nominal | Percentage band |
| 200–300 g/ml | 9 g/ml | Fixed tolerance band |
| 300–500 g/ml | 3% of nominal | Percentage band |
| 500–1,000 g/ml | 15 g/ml | Fixed tolerance band |
| 1,000–10,000 g/ml | 1.5% of nominal | Percentage band |
Information to collect
- Confirm whether the product and quantity fall within the packaged-goods rules.
- Choose and document the minimum or average control system.
- Define tare, sampling, measurement uncertainty and record method.
- Set filler target from process variation and legal/customer requirements.
- Check scales and measuring equipment are suitable for the task.
- Keep required records and investigate trends before failures occur.
Practical method
- 1
Obtain competent weights-and-measures advice for the actual product.
- 2
Measure the current fill distribution.
- 3
Set an operating target that protects the legal rules without unnecessary giveaway.
- 4
Use checkweigh or sampling feedback appropriately.
- 5
Review the system after product, pack or equipment changes.
Common mistakes to avoid
- Treating TNE as the normal production target.
- Checking only the batch average.
- Ignoring tare variation.
- Using a scale with unsuitable resolution.
- Assuming a checkweigher automatically creates legal compliance.
Questions people also ask
What is TNE?
Tolerable negative error is the specified amount by which a package may be below nominal quantity for the second of the three packers’ rules.
Can any pack be below twice the TNE?
No pack in an average-system batch should be short by more than twice the TNE.
Is every product covered?
The GOV.UK guidance defines the packaged goods and quantity ranges within scope; obtain advice for unusual products or selling methods.
How long should records be retained?
GOV.UK states that average-system checking records must normally be retained for at least one year from shipment or until the use-by date, whichever period is shorter.
Official and primary sources
These references support the regulated, standards-led or security points in this guide. Check the current source before making a project decision.
Continue from the requirement to the equipment
Use the specialist route that matches the product, pack and process. Final suitability requires representative samples, output targets and site information.