Fibre Content Label: Declared Blend, Test Result & Tolerance

The formula

This is the expression the tool evaluates. Every term is named underneath, with the unit it must be supplied in.

How the result is derived

Step by step, from the values you type to the figure on screen.

1. The 7 inputs are read from the form on every keystroke: Fibre A Declared, Fibre B Declared, Fibre C Declared, Fibre A Found, Fibre B Found, Fibre C Found and Tolerance Allowed.
2. Each value is checked against the accepted range in the input table below. A value outside its range stops the calculation rather than producing a misleading figure — the results blank out and a message appears.
3. The validated values are substituted into the expression above, which resolves Margin Against Tolerance together with every supporting figure in one pass — no value is carried over from a previous entry.
4. The supporting outputs — Fibre A Deviation, Fibre B Deviation, Fibre C Deviation, Largest Deviation, Fibres Outside the Band, Tolerance Applied, Single-Fibre Claim, Fibre A Lower Limit, Fibre A Upper Limit, Declared Total and Found Total — come from the same pass, so they always describe the same case as the headline figure.
5. Results are rounded for display only. The full-precision value is used throughout the chain, so reading a rounded intermediate figure back into the tool by hand can shift the last digit.

What each input means

Where to read each value on the floor, the unit it must be in, and the range the tool accepts.

What the tool returns

The headline figure and every supporting value it is built from.

Worked example

The tool loads with this case already solved — the Margin Against Tolerance shown above is its answer. Change one value and the difference from this baseline is the sensitivity of the result to that variable.

How to use it

1. Work through the input groups in order — Declared and Found. The defaults are a realistic case, so you can change one value at a time and watch what moves.
2. There is no calculate button. Every figure recalculates as you type or drag, which is what makes this usable for a what-if sweep rather than a single answer.
3. Read Margin Against Tolerance in the dark results panel — that is the headline figure, expressed in pp.
4. Check the supporting rows underneath (Fibre A Deviation, Fibre B Deviation, Fibre C Deviation, Largest Deviation, Fibres Outside the Band, Tolerance Applied, Single-Fibre Claim, Fibre A Lower Limit, Fibre A Upper Limit, Declared Total and Found Total) before acting on the headline — they are where an implausible input usually shows itself first.
5. Reset to defaults returns every field to the reference case, which is the quickest way to check whether a surprising result came from the tool or from an input you had changed earlier.

Where this is used

• Process planning — establishing Margin Against Tolerance before a trial is booked, so machine time and material in Textile Testing & Quality Control are committed against a calculated figure rather than an estimate.
• Costing and quotation — Margin Against Tolerance is an input to the cost sheet, and quoting from a worked number rather than a remembered one is what keeps a margin intact.
• Troubleshooting — when the floor result drifts from plan, entering the measured values (starting with Fibre A Declared) shows how much of the gap in Margin Against Tolerance each variable explains.
• Teaching and study — the accepted ranges bracket normal Textile Testing & Quality Control practice, so moving one variable at a time shows the shape of the relationship rather than a single answer.

Assumptions and limits

• The tolerance is applied as percentage points of the total fibre weight, which is what 16 CFR 303.43(a) provides and what its own worked example shows: a declaration of 40 percent is satisfied anywhere from 37 to 43. A deviation of exactly the tolerance is inside it, because the section speaks of a deviation in excess of the figure. Where a label represents the product as composed wholly of one fibre, paragraph (c) withdraws the tolerance, so this tool applies a band of zero the moment any declared figure reaches 100 - a result of 99.2 against a claim of 100 is outside a band with no width, and reporting it as a deviation of 0.8 against a tolerance of 3 would be the wrong answer twice over. The tolerance field is an input because three percentage points is one jurisdiction's figure, read here from the section itself; a reader working to another market's rule enters that rule's number. Nothing here decides whether a product is misbranded: paragraph (b) leaves that turning on whether the whole deviation arose from unavoidable variation in manufacture despite the exercise of due care, which is a question about a mill and not about arithmetic. Declared and found totals are shown because a test result that does not sum to one hundred is a reason to look at the test before looking at the tolerance.
• Every input is bounded to the range normal practice occupies (Fibre A Declared 0 to 100 %, Fibre B Declared 0 to 100 % and Fibre C Declared 0 to 100 %, and so on for the rest). Those bounds are guard rails against typing errors, not a claim that the formula fails one unit outside them.
• The calculation is deterministic: the same inputs always give the same result. It carries no allowance for machine condition, operator skill, ambient conditions or lot-to-lot material variation unless an input above explicitly represents one.
• Nothing is sent anywhere. The maths runs in your browser, so the numbers you type never leave the page.

Questions people ask