Check whether a ring size chart row is internally consistent. Enter diameter and circumference, optionally choose the claimed Indian size, and get an instant accuracy score with exact millimetre differences.
The Ring Size Chart Accuracy Checker Tool is a free verification calculator for people comparing ring-size tables, printable guides, jeweller charts and online conversion pages. A ring chart normally lists an inside diameter and an inside circumference. Those two measurements should be mathematically related, so the checker compares your values against the circle relationship and against a published Indian ring-size reference table.
Instead of trusting a chart because it looks professional, you can enter one row and see how closely its numbers agree. The result shows a consistency score, the circumference expected from the diameter, the diameter expected from the circumference, the nearest Indian size, and any difference from the claimed size. This is useful when two websites show slightly different values because of rounding, conversion methods or different sizing conventions.
For final jewellery fitting, a professional ring gauge remains the best option. The checker is designed to audit chart data and catch obvious inconsistencies before you use a chart to order a ring.
Enter the diameter and circumference shown on the chart. Indian size is optional but improves the reference comparison.
Use the diameter printed for a single ring-size row. The tool expects millimetres and supports decimals such as 18.50 mm.
Add the circumference from the same row. Do not mix numbers from different sizes or different charts.
If the chart says the row is Indian Size 18, select 18. If you leave it blank, the checker automatically finds the closest reference size.
The calculator derives the expected circumference from the entered diameter and the expected diameter from the entered circumference. Large gaps can indicate a typo, unit mistake or inconsistent chart row.
The result compares your row with the selected or nearest Indian size and summarizes whether the row looks excellent, very good, good or in need of rechecking.
A ring opening is approximately circular. That makes the relationship between inside diameter and inside circumference useful for checking whether a chart row is internally consistent.
The tool does not assume that every published chart must equal π to the last decimal. It displays the raw difference so you can distinguish harmless rounding from a larger mismatch.
The checker uses Indian sizes 1–30 based on the current Tanishq ring-size guide as its reference comparison. The last two columns are calculated by this page to show how the published diameter and circumference relate mathematically.
| Indian Size | Published Diameter | Published Circumference | Diameter from C ÷ π | Geometry Gap |
|---|---|---|---|---|
| Size 1 | 13.10 mm | 41.01 mm | 13.05 mm | 0.14 mm |
| Size 2 | 13.30 mm | 42.70 mm | 13.59 mm | 0.92 mm |
| Size 3 | 13.70 mm | 42.90 mm | 13.66 mm | 0.14 mm |
| Size 4 | 13.90 mm | 43.60 mm | 13.88 mm | 0.07 mm |
| Size 5 | 14.30 mm | 44.80 mm | 14.26 mm | 0.12 mm |
| Size 6 | 14.70 mm | 46.10 mm | 14.67 mm | 0.08 mm |
| Size 7 | 15.10 mm | 47.40 mm | 15.09 mm | 0.04 mm |
| Size 8 | 15.30 mm | 48.00 mm | 15.28 mm | 0.07 mm |
| Size 9 | 15.50 mm | 48.70 mm | 15.50 mm | 0.01 mm |
| Size 10 | 15.90 mm | 50.00 mm | 15.92 mm | 0.05 mm |
| Size 11 | 16.30 mm | 51.20 mm | 16.30 mm | 0.01 mm |
| Size 12 | 16.50 mm | 51.90 mm | 16.52 mm | 0.06 mm |
| Size 13 | 16.90 mm | 53.10 mm | 16.90 mm | 0.01 mm |
| Size 14 | 17.30 mm | 54.40 mm | 17.32 mm | 0.05 mm |
| Size 15 | 17.50 mm | 55.10 mm | 17.54 mm | 0.12 mm |
| Size 16 | 17.90 mm | 56.30 mm | 17.92 mm | 0.07 mm |
| Size 17 | 18.10 mm | 57.00 mm | 18.14 mm | 0.14 mm |
| Size 18 | 18.50 mm | 58.30 mm | 18.56 mm | 0.18 mm |
| Size 19 | 18.80 mm | 58.90 mm | 18.75 mm | 0.16 mm |
| Size 20 | 19.20 mm | 60.20 mm | 19.16 mm | 0.12 mm |
| Size 21 | 19.40 mm | 60.80 mm | 19.35 mm | 0.15 mm |
| Size 22 | 19.80 mm | 62.10 mm | 19.77 mm | 0.10 mm |
| Size 23 | 20.00 mm | 62.70 mm | 19.96 mm | 0.13 mm |
| Size 24 | 20.40 mm | 64.00 mm | 20.37 mm | 0.09 mm |
| Size 25 | 20.60 mm | 64.60 mm | 20.56 mm | 0.12 mm |
| Size 26 | 21.00 mm | 65.90 mm | 20.98 mm | 0.07 mm |
| Size 27 | 21.10 mm | 67.20 mm | 21.39 mm | 0.91 mm |
| Size 28 | 21.60 mm | 67.80 mm | 21.58 mm | 0.06 mm |
| Size 29 | 22.00 mm | 69.10 mm | 22.00 mm | 0.02 mm |
| Size 30 | 22.30 mm | 71.00 mm | 22.60 mm | 0.94 mm |
One chart may list diameter to one decimal place while another uses two. A 0.1 mm change in displayed diameter creates a noticeable but small circumference difference after multiplication by π.
Indian, US, UK, EU and Asian sizing systems do not share one universal numbering scale. A conversion table often chooses the nearest practical equivalent instead of a mathematically exact match.
PDF and on-screen ring templates can become inaccurate when a browser, printer or PDF viewer scales the page. A chart can contain correct numbers while its printed circles are physically the wrong size.
Use the accuracy checker as one layer in a wider sizing process. First, verify the chart itself. Next, measure a ring that already fits or have your finger measured with a sizing gauge. Finally, convert to another country's sizing system only after the physical diameter or circumference is known.
Use this Ring Size Chart Accuracy Checker Tool to confirm the row is internally consistent.
Use our Find My Ring Size India tool or compare a well-fitting ring's inside diameter.
If the seller uses another system, use the India Ring Size Converter rather than guessing from size labels.
For engagement rings, wide bands and designs that may be difficult to resize, professional confirmation can prevent costly fit problems.