UK tolerable negative error (TNE) calculator
Enter a nominal quantity from 5 g or ml to 25,000 g or ml to look up the applicable GB TNE band and calculate the corresponding one-TNE and two-TNE planning thresholds.
How do I calculate tolerable negative error?
Find the nominal quantity band in the official table, then apply either its fixed TNE or its percentage of nominal quantity. Where a percentage is used, the result is rounded up to the nearest 0.1 g or ml. This tool performs that lookup and rounding, then subtracts one TNE and two TNEs from the nominal quantity.
Enter the declared nominal quantity
Use grams for weight or millilitres for volume. The same numerical bands apply, but keep the unit consistent throughout your review.
This calculator reflects the current Great Britain guidance range of 5 g/ml to 25,000 g/ml. It is not legal advice, a compliance decision, or a source of machine settings. The packer or importer remains responsible for verifying the current rules, quantity-control method, calculations, checks and records. Confirm the application with your legal or quality adviser and Local Authority Trading Standards before implementation.
GB tolerable negative error bands used by this calculator
Fixed bands use the stated amount. Percentage bands are calculated from nominal quantity and rounded upward to the nearest 0.1 g or ml.
| Nominal quantity | TNE rule | Calculator treatment |
|---|---|---|
| 5 to 50 g/ml | 9% of nominal quantity | Percentage result rounded up to 0.1 g/ml |
| Over 50 to 100 g/ml | 4.5 g/ml | Fixed TNE |
| Over 100 to 200 g/ml | 4.5% of nominal quantity | Percentage result rounded up to 0.1 g/ml |
| Over 200 to 300 g/ml | 9 g/ml | Fixed TNE |
| Over 300 to 500 g/ml | 3% of nominal quantity | Percentage result rounded up to 0.1 g/ml |
| Over 500 to 1,000 g/ml | 15 g/ml | Fixed TNE |
| Over 1,000 to 10,000 g/ml | 1.5% of nominal quantity | Percentage result rounded up to 0.1 g/ml |
| Over 10,000 to 15,000 g/ml | 150 g/ml | Fixed TNE |
| Over 15,000 to 25,000 g/ml | 1% of nominal quantity | Percentage result rounded up to 0.1 g/ml |
Official sources used
The calculator follows the TNE table and rounding instruction published for packaged goods in Great Britain. Always check the live sources for amendments.
TNE is only one part of the average system
Official guidance describes three packers’ rules. A calculated TNE does not by itself prove that a batch, process or individual package complies.
Average quantity
The contents of packages in the batch must not be less, on average, than the nominal quantity. This calculator does not assess a batch mean.
Packages beyond one TNE
Only a permitted small proportion may be short by more than one TNE. Determining that proportion requires the applicable checking and assessment method.
No package beyond two TNEs
The guidance states that no package should be short by more than twice the TNE. Your operating controls still need suitable equipment, verification and response.
Do not copy a calculated threshold straight into a checkweigher
Legal quantity control, process warning limits and automatic reject limits serve different purposes. Product and packaging variation, tare method, dynamic measurement performance, test procedures, uncertainty, reject integrity and the site’s documented quality method all affect the final configuration.
Define the legal and quality decision first, then verify that the proposed in-line checkweigher can make that decision reliably with representative products at production speed.
- Declared nominal quantity
- Applicable packing method
- Tare and product variation
- Dynamic capability evidence
- Warning and reject philosophy
- Routine challenge procedure
- Reject confirmation and containment
- Records and corrective action
TNE calculator FAQs
Practical answers for engineering, production and quality teams using the tool at an early planning stage.
What is tolerable negative error?
Tolerable negative error, usually shortened to TNE, is the defined amount by which a package may be below its nominal quantity for the purposes of the average-system rules. Its value depends on the nominal quantity band.
What do T1 and T2 mean in this calculator?
T1 is shown as nominal quantity minus one TNE. T2 is nominal quantity minus two TNEs. They are threshold calculations for planning and discussion; the labels do not replace the full legal assessment, batch rules or site operating method.
How are percentage TNE values rounded?
The official guidance says that when TNE is calculated as a percentage of nominal quantity, the amount must be rounded up to the nearest one tenth of a gram or millilitre. The calculator applies that upward rounding before calculating T1 and T2.
Can I use T1 or T2 as a checkweigher reject setting?
Not without a documented application assessment. Reject settings must account for the legal and quality method, tare treatment, product variation, demonstrated dynamic performance, test procedure and the required response to uncertainty or failure.
Does the calculator prove compliance with the three packers’ rules?
No. It performs one TNE lookup and threshold calculation. It does not assess batch average, the permitted proportion below T1, sampling, equipment suitability, records or corrective action.
Does this calculator apply in Northern Ireland?
This page is expressly based on the cited Great Britain guidance for England, Scotland and Wales. For Northern Ireland, exports, e-marked goods or unusual products, obtain advice on the rules that apply to the specific supply route.
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