About Mesurix: who makes the ring sizer and why

Mesurix is published by VAST FLOW, TOO and built by Merey Tleugazin. Merey is a software developer, not a jeweller or a gemmologist. That is not a footnote to hide. It tells you what Mesurix is designed to do: explain ring-size arithmetic, put a calibrated measuring surface on a phone, and make conversions between sizing systems easier to check.

Mesurix does not present software development as jewellery trade experience. It does not claim that a phone, sheet of paper or browser tool is the same as a jeweller’s steel mandrel. The useful claim is narrower: once a screen has been calibrated and an object has been positioned properly, the calculations applied to the measured value are exact.

Who publishes Mesurix and who builds it?

Merey Tleugazin is the founder of VAST FLOW, TOO and the person who builds Mesurix. VAST FLOW, TOO publishes the Mesurix app. Merey also writes and maintains the site, including its explanations of ring-size standards, card calibration and measurement limits.

The Mesurix tools include the browser ring sizer, calibrated ruler and bubble level. The ring sizer tool runs without an account. Its calibration is stored as one number in the browser’s localStorage rather than in a user profile on a server.

The app is free on iPhone and Android, supports iOS 13 or later, and works offline. It adds saved sizes and profiles, every standard on one screen, a finger-measure mode, a printable sizer, the on-screen ruler and a bubble level with a set-zero step. These features make repeated measurements and conversions easier to manage. They do not make the phone a jewellery workshop instrument.

That distinction matters when a ring purchase depends on less than 1 mm. A software tool can calculate a conversion consistently. It cannot feel the resistance of a ring over a knuckle, inspect the inside shape of a finished band or decide whether a particular design is comfortable on a particular finger.

Merey writes the site as well as building the app. If a formula, conversion or explanation needs checking, send the details through the contact page. Include the page, the exact wording and the source or calculation that supports the correction. A specific report can be checked; a general statement that a result looks wrong cannot identify whether the problem is a unit, a decimal point or a disagreement between sizing systems.

Why does Mesurix calibrate against a bank card?

A phone screen is not automatically a ruler. A browser can know the number of CSS pixels in an element, but it cannot know the physical size of those pixels on the panel in front of you. A CSS pixel is defined against a 96 dpi reference display. The definition does not tell the browser how many millimetres a CSS pixel occupies on a particular phone.

That is why the same displayed ring outline can have different physical sizes on two panels. Screen resolution, display dimensions and device settings can change the relationship between the browser’s coordinate system and the object you can touch.

Calibration supplies the missing physical length. Mesurix asks you to compare the screen with a bank card, then uses that comparison to set the displayed millimetres. The browser tools run entirely in the page, need no account and upload nothing. The calibration value is one number stored in localStorage.

The reference is not an arbitrary rectangle. ISO/IEC 7810 ID-1 specifies a card measuring 85.60 mm × 53.98 mm. Bank cards use this format, as do most national identity cards, driving licences and many transport cards. It is the most widely distributed physical length standard in the world, so a card is a practical reference object when a dedicated ruler is not nearby.

Use the long or short edge that the calibration step asks for, and align the card with the on-screen marks. A card that is tilted, placed against the wrong line or compared with a browser view that has been zoomed can produce a wrong scale. A bent, worn or damaged card can also make its edge harder to align. Calibration fixes the scale only if the comparison itself is made carefully.

Once the scale is set, Mesurix can draw a ring outline or a ruler in millimetres. The displayed arithmetic is not the weak point. The physical inputs are. Moving a ring outline off centre, holding a finger at an angle, reading the wrong edge or accepting the first close-looking alignment can shift the result.

The ring-size guide explains how to take and repeat a measurement. The ring size chart helps when a seller uses a national system different from the one shown by the app. A chart converts labels; it does not remove the need to measure the finger and check the seller’s convention.

Where do Mesurix ring-size numbers come from?

A ring size describes a physical dimension. For Mesurix’s underlying model, that dimension is the inner diameter of the band in millimetres. Some sizing systems display that same ring using its inner circumference, a letter or a numbered scale. The labels differ, but the ring itself still has one inside measurement.

For US and Canadian sizes, Mesurix uses this formula:

diameter (mm) = 11.63 + 0.8128 × size

The calculation gives US 7 as 17.32 mm. Increasing the US size by one whole size increases the inner diameter by 0.8128 mm and changes the circumference by about 2.55 mm. That is a small-looking change with enough effect to determine whether a ring clears the knuckle.

The EU and ISO 8653 scale uses the inner circumference in millimetres as the size. On that scale, 54 mm is US 7. The EU/ISO number is therefore not a diameter measurement, even though the same ring can be converted to a diameter for comparison with the US scale.

France and Switzerland use a related number. Their size equals the circumference in millimetres minus 40. FR 14 means a 54 mm circumference, which corresponds to US 7.

The UK, Australian and Irish scale uses letters and half-letter steps. Its circumference formula is:

circumference (mm) = 37.14 + 1.28 × s

Here, s counts half-letter steps from A. On this scale, US 7 is UK N 1/2. The half step is part of the system, not a rounding error or an informal extra label.

Japan uses the JIS scale. Korea and China use the same numbered scale in the form described here. The formula is:

diameter (mm) = 13 + (n − 1) / 3

The inverse formula is:

n = 3 × diameter − 38

US 7 is JP 14. The same physical size is therefore labelled 14 on the Japanese numbered scale, 54 on the EU/ISO circumference scale and N 1/2 on the UK scale.

Korean listings need a separate check because the same-looking number can describe different things. Korean sellers quote the same 호 numbers as the Japanese 号 scale, but some Korean shops use 호 for circumference in millimetres instead. Look for a millimetre figure next to the number. Do not treat a Korean 호 number as Japanese-style automatically.

This reference row puts the systems beside one another:

The 54.4 mm circumference comes from the 17.32 mm inner diameter multiplied by π. EU/ISO 54 does not contradict that 54.4 mm physical circumference. ISO 8653 uses a whole-millimetre circumference label, while the US formula gives the underlying diameter to two decimal places.

The reference row also shows why a seller’s country is not enough information. A listing marked “14” could be a Japanese-style numbered size, but a Korean listing may instead place a circumference in millimetres beside its 호 notation. Read the unit and the scale name before ordering.

How much can a fraction of a millimetre change?

A sheet of 80 gsm office paper is about 0.10 mm thick. A human hair is about 0.07 mm thick. One whole US size is 0.81 mm of inner diameter, roughly eight sheets of that paper. An alignment that looks close on a phone can therefore represent a meaningful difference in ring fit.

That comparison explains why “almost touching” is not a measurement. A line can appear to meet an outline while still being separated by a fraction of a millimetre. Read the numerical result, check the centre and repeat the placement instead of judging the image by eye once.

String and paper-strip methods have another failure mode. They stretch and compress. The amount of pull changes the length, so these methods can read a quarter to a half size high or low depending on how hard the material is pulled. A strip pulled tightly is not measuring the same circumference as a strip held gently.

If you use a strip, keep the tension consistent and repeat the result. Then compare it with a calibrated screen or have a jeweller check it before buying a costly ring. The problem is not that string is useless; it is that the material changes length under the hand taking the measurement.

When should you measure your finger?

Finger size changes during the day. Fingers are largest late in the day, after heat, exercise or salty food, and smallest on a cold morning. The spread across one day is easily a quarter of a US size.

A single reading is a record of that moment, not a permanent property of the finger. Measure more than once in ordinary conditions. If the results move between two sizes, use the larger size because the ring must pass over the knuckle to go on and off.

A loose ring can be tightened with sizing beads or a fitted bar. A ring that cannot clear the knuckle cannot be worn at all. That is why choosing the larger option between two plausible sizes is the practical rule, even though a smaller ring may appear closer to the measured diameter.

Band width changes the choice too. The trade rule of thumb is about a quarter size up from 6 mm of width and about a half size up from 8 mm. A wide band covers more of the finger and can feel tighter than a narrow band at the same nominal size.

The rule applies to the band you intend to buy, not just to a sample ring used for comparison. A narrow existing ring may fit while a new 8 mm band does not. Measure the finger, note the proposed band width and check the seller’s return policy before treating a converted label as the final order.

What can Mesurix measure, and what can it not decide?

Mesurix is a measuring and conversion tool, not a jewellery shop, gemmological laboratory or certified measuring service. Its honest claim is exact arithmetic on a measurement that is only as good as the reader’s calibration and handling.

No screen or paper measurement is equal to a jeweller’s steel mandrel. A calibrated phone can help establish a ring’s inside diameter, compare a seller’s size label with another system and check a small object’s length with the on-screen ruler. It cannot reproduce the feel of a ring passing over a knuckle or inspect the construction of the finished band.

The display also cannot know whether the finger is larger after exercise, heat or salty food, or smaller on a cold morning. It receives the measurement supplied by the person using it. Repeating the measurement in ordinary conditions gives a better basis for a decision than treating one reading as fixed.

A displayed ring outline is not a guarantee that a finished ring will fit. Band width, interior shape, knuckle size and the seller’s manufacturing tolerance can all affect the result. These are reasons to use the number carefully, not reasons to pretend that a conversion formula can choose the ring by itself.

For an expensive or non-returnable ring, confirm the size with a jeweller before placing the order. This is especially important when measurements fall between sizes, when the band is 6 mm or wider, or when a seller’s national sizing label does not show a millimetre measurement.

How is Mesurix funded if the tools are free?

Mesurix’s public tools are free, do not show adverts and do not sell personal data. VAST FLOW, TOO publishes and maintains the app as the product behind the site. The funding explanation is therefore not an advertising or data-collection feature hidden inside the measuring flow.

The browser tools need no account. They run entirely in the page, and nothing is uploaded. Calibration is stored as one number in localStorage. The privacy page explains the site’s data position, while the terms page sets out the conditions for using the service.

The app is free on iPhone and Android, supports iOS 13 or later and works offline. Saved sizes and profiles help keep repeated personal results together. Every standard appears on one screen, and the app also includes finger-measure mode, a printable sizer, the calibrated on-screen ruler and a bubble level with a set-zero step.

Offline operation changes where the software needs a connection; it does not change the physical uncertainty of a finger measurement. Saved profiles keep previous results available; they do not prove that a finger has the same size on another day. The app makes repeated use more convenient without turning a phone into a steel mandrel.

The browser tools and the app are therefore free software products with a clearly limited job. They calculate, display, convert and retain the settings needed for use. They do not claim certified, guaranteed or laboratory accuracy, and they do not replace a jeweller when the cost or return conditions make a wrong size difficult to fix.

How can you send a correction to Mesurix?

Send corrections to formulas, conversions, standards or explanations through the contact page. Include the page address, the exact statement that needs checking and the source or calculation that supports the proposed change.

A correction is easiest to investigate when it names the failure. Say whether the issue is a wrong unit, an incorrect national conversion, a misplaced decimal point, an inaccurate standard reference or a description of an app feature. “This looks wrong” does not distinguish a calculation error from a seller using a different ring-size convention.

Mesurix identifies the sources and scales used in its calculations. ISO/IEC 7810 ID-1 defines the 85.60 mm × 53.98 mm card format used for screen calibration. ISO 8653 defines the millimetre circumference ring scale. The US and UK trade scales supply their stated formulas, and JIS supplies the Japanese numbered scale.

Those references make a correction checkable. For example, a reader can separate the question “does this card have the ID-1 dimensions?” from the question “does this seller use EU 54 or a Korean circumference figure?” The two questions concern different measurements and should not be collapsed into one general claim about accuracy.

Tell Mesurix when a limitation is unclear as well. The site is intended to help with measurement and conversion, not to replace a jeweller’s inspection or fitting advice. An expensive or non-returnable ring still deserves confirmation with a jeweller, especially when the measured result sits between sizes or the proposed band is wide.

Merey Tleugazin maintains the software and the explanations for VAST FLOW, TOO. Sending a correction by email gives the publisher the details needed to revise a page and gives readers a direct route to question the person responsible for Mesurix’s measurement claims.