Luhn Checksum Calculator

Luhn Checksum Calculator | Elysia Tools

Tool usage guide

Learn when to use this tool, what it supports, and how real users apply it.

Key facts

Category: Validation
Input types: select, text, number
Output type: text
Sample coverage: 4
API ready: Yes

Overview

The Luhn Checksum Calculator allows you to validate or generate numbers using the Luhn algorithm (mod-10). It supports standard identifiers such as credit cards, IMEI, IMEISV, Social Insurance Numbers (SIN), National Provider Identifiers (NPI), and custom Luhn-based numbers, ignoring spaces and dashes automatically.

When to use

When you need to verify if a credit card number, IMEI, or NPI is syntactically valid before processing it.
When generating mock test numbers with valid check digits for software testing and QA environments.
When calculating the correct check digit for a custom sequence of numbers that uses the mod-10 Luhn algorithm.

How it works

1Select the mode: either 'Validate' to check an existing number or 'Generate' to create a new one.
2For validation, enter the number; the tool strips non-digit characters and computes the mod-10 checksum.
3For generation, specify the desired total length and an optional prefix to lock the leading digits.
4The tool instantly outputs the validation status or the generated number with its correct check digit.

Use cases

Validating user-entered credit card numbers in a checkout form mock-up to ensure basic format correctness.
Generating a batch of valid IMEI numbers for testing mobile device registration systems.
Calculating the final check digit for custom internal membership or inventory tracking numbers.

Examples

1. Validating a Credit Card Number for a Checkout Form

Frontend Developer

Background

A developer is building a payment form and wants to test the client-side validation logic with a real-looking but dummy credit card number.

Problem

They need to verify if a specific test card number has a valid Luhn checksum.

How to use

Set the mode to 'Validate' and enter the card number into the 'Number to Validate' field.

Mode: Validate, Number: 4532 0151 1283 0366

Outcome

The tool strips the spaces, calculates the mod-10 checksum, and confirms whether the number is valid.

2. Generating Test IMEI Numbers for QA Testing

QA Engineer

Background

A QA engineer needs to test a database schema that accepts 15-digit IMEI numbers, requiring valid check digits to pass validation.

Problem

They need to generate a valid 15-digit number starting with a specific TAC prefix.

How to use

Set the mode to 'Generate', set the total length to 15, and enter the desired prefix.

FAQ

What is the Luhn algorithm?

It is a simple checksum formula (mod-10) used to validate a variety of identification numbers, protecting against accidental typing errors.

Does this tool store the credit card or IMEI numbers I enter?

No, all calculations are performed locally in your browser, and no sensitive data is sent to any server.

Can I generate numbers with specific prefixes?

Yes, you can set an optional prefix, such as 4 for Visa or 35 for JCB, to lock the leading digits of the generated number.

How does the tool handle spaces or dashes in the input?

The calculator automatically ignores spaces, dashes, and other non-digit separators during validation.

Does a valid Luhn checksum mean a credit card is active?

No, it only confirms the number is mathematically valid. It does not verify account status, balance, or active status with the issuer.

Mode: Generate, Total Length: 15, Prefix: 35

Luhn Checksum Calculator

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Learn when to use this tool, what it supports, and how real users apply it.

Key facts

Overview

When to use

How it works

Use cases

Examples

1. Validating a Credit Card Number for a Checkout Form

2. Generating Test IMEI Numbers for QA Testing

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