Convert a source-owned paper grammage or basis-ream mass with explicit basis dimensions and sheet count, then optionally reconcile a same-basis reported value.
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A quick decision brief for this specific tool
Inputs that matter
One de-identified source-owned paper conversion record; record type, source record ID, paper-stock identity, source specification and conversion time; grammage-to-basis or basis-to-grammage direction; one GPO preset or custom basis definition with positive width, height, inch or millimetre dimension unit, positive whole sheet count and basis-definition source; one positive input in g/m², basis-ream lb or basis-ream kg and a compatible lb/kg output selection; reviewer role, review time, retention record and six refusal boundaries; plus an optional all-or-none independent same-basis value, compatible unit, source and reviewer-owned basis-match record
Output to expect
Explicit basis width and height in millimetres, total basis-ream area in square metres, grammage in g/m², basis-ream mass in kilograms and pounds, one direction-specific primary result, exact unit-normalization evidence and an optional calculated-minus-independent signed difference without pass/fail
How it works
Validate the complete stock, source, basis-definition and boundary record; load a GPO basis-size preset only as explicit geometry or retain custom source geometry; normalize inches with exactly25.4mm and pounds with exactly0.45359237kg; calculate grammage = basis-ream kilograms×1000 ÷ basis-ream square metres or reverse that relation; require every independent field and the reviewer-owned same-basis match before comparing; preserve six nondecisions and versioned Project outputs
Confirm the exact paper/product/lot or specification, basis width, basis height, sheet count, dimension unit, mass unit and source revision. A paper name such as bond, text, cover or index does not by itself establish the source basis definition.
Treat GPO presets as explicit500-sheet basis geometry, not proof that another supplier, specification or historical record uses that same basis or sheet count. Use custom values when the source definition differs.
If comparing an independent value, confirm the exact same stock record, basis dimensions, sheet count, mass/area definition and units. A small or zero difference is arithmetic/transcription evidence only—not measurement validity, tolerance, equivalence, quality or acceptance.
Use the result only for mass-per-area and stated-basis ream-mass arithmetic. It does not infer caliper, thickness, bulk, density, stiffness, grain, finish, coating, opacity, strength, runnability, fold/bind/print/packaging suitability, environmental claim or standards-conforming test result; select stock, supplier or process; approve a quote, purchase order, production, release, compliance or safety decision; or certify equivalence.
Choose your path
Built around the job you need to finish
Convert one source-owned paper grammage or explicitly defined basis-ream mass in either direction, optionally reconcile one independently reported same-basis value, and refuse every thickness, stiffness, equivalence, stock-selection, procurement, production, compliance and safety decision.
Print buyer reconciling a supplier specification
Translate a supplier's stated basis-ream mass into grammage without assuming that a paper-family label defines the basis size or sheet count.
Identify the stock and source specification, load a source-verified GPO geometry or enter the custom basis, convert, review the boundary record and retain a snapshot.
Can hand off reproducible mass-per-area arithmetic while stock equivalence, suitability, pricing, order and acceptance decisions remain external.
Prepress reviewer checking a counterpart value
Compare a calculated grammage or ream mass with one independently reported value on exactly the same basis without turning closeness into product approval.
Freeze stock identity, geometry, sheet count and units, enter the complete independent source/match tuple, then inspect the signed difference and retained basis evidence.
Gets a transparent transcription check while measurement method, tolerance, condition, caliper, runnability and release remain with accountable evidence and reviewers.
Graphic-production instructor teaching paper-weight systems
Demonstrate why grammage and named U.S. basis weights require explicit area/count records and why neither determines thickness or suitability.
Load the20lb writing/bond example, exercise all presets, custom inch/millimetre geometry and both directions, trigger mismatch/partial-evidence errors, then review every nondecision.
Learners can reproduce the conversion and explain why caliper, stiffness, stock choice, printing, folding, binding, packaging and purchasing require separate evidence.
Authoritative checks for this tool
Outputs and checklists are planning aids. Review the linked current authorities and the records, terms, instructions, and requirements that apply to your exact situation before a consequential decision.
ISO 536 and TAPPI T 410 treat grammage as mass per unit area. A U.S. basis or ream weight is the mass of a stated number of sheets at a stated basis size, so the width, height and sheet count are part of the conversion record.
Grammage (g/m²) = basis-ream mass (kg) × 1000 ÷ basis-ream area (m²)
Normalize only recorded units
The calculation uses exactly 25.4 millimetres per inch and 0.45359237 kilograms per pound. It retains the entered geometry and sheet count instead of using a rounded family multiplier.
Basis-ream area = width × height × sheet count; basis-ream mass = grammage × area ÷ 1000
Presets are explicit source geometry
The optional writing/bond, book/text/offset, cover and index presets copy 500-sheet basis dimensions published by the U.S. Government Publishing Office. They are not universal defaults; use a custom definition whenever the controlling specification states another size or count.
Use preset only when source basis width, height and sheet count match
Updated: July 2026
Example Scenarios
For an explicitly documented 17×22 inch, 500-sheet basis, 20 lb per basis ream converts to about 75.195 g/m². Keep the source definition with the number; this does not certify an equivalent product.
For a source-confirmed 20×26 inch, 500-sheet basis, 100 lb per basis ream converts to about 270.411 g/m². The result states mass per area only and does not predict caliper, rigidity or end-use performance.
Enter the source's exact custom dimensions, dimension unit and 480-sheet count before converting a reported grammage to pounds or kilograms per basis ream. Do not silently replace the count with 500.
Common Mistakes to Avoid
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Choosing a paper-family preset from its name alone
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Copy the controlling source's width, height and sheet count. Use a preset only when those three values match; otherwise select the custom basis definition.
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Treating a converted number as a stock decision
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Use the result only as mass-per-area and basis-ream-mass arithmetic. Verify physical properties, conditioning, process fit, supplier evidence, price, order terms and acceptance separately.
FAQ
Basis-ream mass describes the mass of a stated sheet count at a stated sheet size. Without all three values, the total basis area is unknown and a unique grammage conversion is not supported.
No. They provide explicit geometry from one official specification source. Confirm the controlling supplier, standard or historical record and use custom geometry or count whenever it differs.
No. Matching mass per area does not establish thickness, density, stiffness, fiber, coating, finish, opacity, strength, grain, dimensional response, printability or suitability.
No. ISO 534 treats thickness, density and specific volume as separately measured properties. This Tool deliberately produces no caliper estimate.
It reports a signed arithmetic difference only after you affirm the same stock, basis geometry, sheet count and mass/area definition. It does not validate measurement, tolerance, quality, acceptance or compliance.
About Paper Grammage & Basis-Weight Converter
Create one reviewed conversion record for a specific paper stock and source specification. State the exact basis width, height and sheet count, convert between mass per area and basis-ream mass with exact unit factors, and optionally compare one independently reported value on the same basis. The result does not infer thickness, stiffness, equivalence or stock suitability and does not approve purchasing, printing, binding, packaging or compliance decisions.
