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RUT Validator

Checks a Chilean RUT, including the K that appears when the check value comes out as ten.

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In short A Chilean RUT ends in a check character that is usually a digit and is sometimes the letter K, and that K is the whole story: the check value is computed mod 11 and so runs from 0 to 10, and ten needs a single character. Chile chose K. The sum uses cyclic weights 2 to 7 applied from the right, which gives a prime modulus and, measured over 3,000 generated cases, catches every single-digit error and every adjacent transposition — one of the strongest schemes here. The same number is called RUN when it identifies a person and RUT when it identifies a taxpayer, but it is one number with one check rule. A passing check does not prove the RUT was issued.

How to use the RUT Validator

  1. Paste the number — punctuation and spaces are ignored.
  2. Read the verdict and, where the number encodes anything, what it decodes to.
  3. Treat a pass as "typed correctly", not as "confirmed by the authority".

About the RUT Validator

A Chilean RUT ends in a check character that is usually a digit and is sometimes the letter K, and that K is the whole story: the check value is computed mod 11 and so runs from 0 to 10, and ten needs a single character. Chile chose K. The sum uses cyclic weights 2 to 7 applied from the right, which gives a prime modulus and, measured over 3,000 generated cases, catches every single-digit error and every adjacent transposition — one of the strongest schemes here. The same number is called RUN when it identifies a person and RUT when it identifies a taxpayer, but it is one number with one check rule. A passing check does not prove the RUT was issued.

What people use it for

  • Catching a mistyped number in a form before it reaches a database.
  • Cleaning an imported list and finding the rows that cannot be right.
  • Understanding what the number encodes and what it does not.

Details

Check character0 to 9, or K when the value is ten
WeightsCyclic 2, 3, 4, 5, 6, 7 applied from the right
Typo detection100% of single-digit errors and 100% of adjacent transpositions
RUT or RUNThe same number — RUN for a person, RUT for a taxpayer
PrivacyChecked locally in your browser
Because the modulus is prime and the weights cycle without repeating adjacent values, the RUT catches every transposition — which the Turkish and Polish schemes on this site do not. Nothing you paste is transmitted — the check runs entirely in your browser.

Where this tool stops

Internal consistency only. It cannot confirm the RUT was issued or is active.

Frequently asked questions

Why does my RUT end in K?
Because the check value came out as ten. A mod-11 check has eleven possible results and only ten digits to express them, so Chile uses K for the eleventh. Roughly one RUT in eleven ends in K, and it is entirely normal.
Is RUT the same as RUN?
Yes, the same number. RUN — Rol Único Nacional — is the term used when it identifies a person; RUT — Rol Único Tributario — when it identifies a taxpayer. The digits and the check character are identical.
Do the dots and dash matter?
No. 12.345.678-5 and 123456785 are the same number; the formatting is a convention for readability. This validator ignores dots, dashes and spaces.
Is anything I paste sent anywhere?
No. The arithmetic runs in this browser tab and no request is made — open your Network tab and watch while you type. That matters more for an identity number than for almost anything else on this site, which is why there is no server side to this tool at all.
Does this replace an official check?
No, and it cannot. Every scheme here proves at most that the digits are internally consistent. Only the issuing authority can confirm a number exists, is active, and belongs to a particular person.
Does the RUT Validator cost anything?
There is no cost and no cap. The RUT Validator is not a demo of a paid product, so nothing is held back or watermarked.
Is my data uploaded anywhere?
No. The RUT Validator runs entirely in your browser using JavaScript. Your input never reaches inputtesthub.com or any third party — open your browser's Network tab while you use it and you will see no request go out.
What problem does the RUT Validator solve?
Typical uses: catching a mistyped number in a form before it reaches a database. Cleaning an imported list and finding the rows that cannot be right. Understanding what the number encodes and what it does not. It is built for exactly those cases rather than being a general-purpose tool with this bolted on.
Where does the RUT Validator stop being reliable?
Internal consistency only. It cannot confirm the RUT was issued or is active. Knowing where a tool stops being trustworthy matters more than the cases where it works.
What are the key numbers for the RUT Validator?
Check character is 0 to 9, or K when the value is ten. Weights is Cyclic 2, 3, 4, 5, 6, 7 applied from the right. Typo detection is 100% of single-digit errors and 100% of adjacent transpositions. These are printed on the page itself, so you do not have to take them on trust.
Is there an app version?
Yes. The page is responsive and the tool works in Chrome, Safari, Firefox, Edge and Samsung Internet on both Android and iOS. There is no app to install and nothing to sign into.

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