Tutorials
Claude Opus 5.5: check product dimensions in cm and inches
Use Claude Opus 5.5 to review a dimension table by identifying the original measurement, converting from that source once, and checking the labels beside the result.
Use Claude Opus 5.5 to review a dimension table by identifying the original measurement, converting from that source once, and checking the labels beside the result. A correct number can still describe the wrong object: product dimensions and shipping-box dimensions must remain separate.
This is a proposed review workflow with a calculated fictional example, not a test of Opus or a measurement of a real product. NIST defines one inch as exactly 25.4 millimeters, so centimeters divided by 2.54 give inches. The conversion factor is exact; the original measurement may not be.
Diagnose the field before doing arithmetic
| What you find | What to check | Appropriate action |
|---|---|---|
| A number without a unit | Supplier source and column heading | Ask for the unit; do not guess |
| Product and package tables disagree | Object being measured | Preserve both, with explicit labels |
| Converted values change on each export | Conversion direction and rounding history | Regenerate from the canonical source |
| A size chart promises a fit | Measurement method and size standard | Do not infer fit from unit conversion |
A merchant asking for centimeter and inch display in a Shopify size chart illustrates the display need. That discussion does not establish that any conversion app preserves measurement accuracy or that the workflow here improves sales.
Work one example from the original values
Suppose a fictional organizer is recorded as **30 × 20 × 12 cm**, ordered length × width × height. Display precision for this example is two decimal places in inches.
| Axis | Original cm | Calculation | Display inches |
|---|---|---|---|
| Length | 30 | 30 / 2.54 | 11.81 |
| Width | 20 | 20 / 2.54 | 7.87 |
| Height | 12 | 12 / 2.54 | 4.72 |
The resulting label is **11.81 × 7.87 × 4.72 in (L × W × H)**. Retain **30 × 20 × 12 cm** as the source record. Converting the displayed 11.81 in back yields 29.9974 cm, not the original 30 cm. This is rounding loss, not a newly discovered measurement discrepancy. Never use the rounded display as the source of the next export.
Two decimal places are a presentation choice, not evidence of hundredth-inch measurement accuracy. Keep any supplied tolerances and measurement method. Missing tolerances stay unknown. If the package is 34 × 24 × 16 cm, give it a separate row; do not replace the product measurements. Area and volume require squared and cubed conversion factors, respectively, and are outside this length-only table.
Give Opus a bounded review prompt
The official Opus 5.5 prompting guide provides model guidance. Adapt this complete task prompt:
Review this product dimension table for a bilingual-unit listing. Inputs: the supplier's original table, original unit, product identifier, axis order, measurement method, any tolerances, and the proposed display table. Keep product measurements separate from shipping-package measurements.
For every length, convert from the original source using 1 in = 2.54 cm. Show the unrounded calculation and the value rounded once to the requested display precision. Preserve the original value and unit. Do not infer a missing unit, tolerance, axis, or apparel fit. Flag ambiguous fields before proposing changes.
Return a table containing field, source value, source unit, object measured, axis, calculation, display value, and issue. Then return the smallest proposed corrections and acceptance checks. Check that the three dimensions retain their original order and that a unit is visible next to the final label. Do not overwrite source data. Distinguish computed checks from facts that still require supplier confirmation.Verify the exported listing
Inspect both the data export and the customer-facing page. Match the SKU first, then the object, axis order, and units. Recalculate at least the longest and shortest dimension directly from the original values. Compare every row in a small table; sampling is not full-table verification.
Switch units and reload. The original centimeter values must remain unchanged, and the inch label must stay attached to the intended product variant. Check mobile wrapping: a unit pushed to a separate card can make a correct value ambiguous. If a supplier corrects a source measurement, regenerate both displays from the corrected source and keep a revision note.
Questions before publishing
**Should every listing use two decimals?** No. Choose precision that fits the source measurements and the reader's decision. Document the rounding rule.
**Can converting units fix a size chart?** It can fix arithmetic. It cannot validate the measurement method, garment fit, or mislabeled axes.
**Should the AI write directly into the catalog?** Review a proposed diff first and validate the saved export. Fluent explanations are not arithmetic evidence.
Once the dimensions are approved, use Panelly Studio to create a complete product image with the verified size information. Keep the authoritative measurements beside the brief. For extracting the source facts from a document, see the PDF product-specification review. This workflow does not imply that Panelly integrates Opus.
