Barcode Check Digit Calculator
Enter the body of a UPC, EAN or GTIN and we'll compute the correct check digit — with a full step-by-step breakdown. Auto-detect picks GTIN-8, GTIN-12, GTIN-13 or GTIN-14 from the body length (7, 11, 12 or 13 digits), and the complete code can be copied in one click.
All math happens in your browser. Nothing is uploaded.
Result
Enter the body digits and the check digit will appear here, with the full weighted-sum breakdown.
Supported Barcode Types
The calculator handles every GTIN length that uses the GS1 mod-10 algorithm.
Small retail packages where space is tight.
Standard US and Canadian retail barcode.
Global retail standard outside North America.
Cases, cartons and pallets in logistics.
Examples
Verified samples for every supported format. The complete code is the body with the calculated check digit appended.
| Format | Body | Check digit | Full code |
|---|---|---|---|
| GTIN-8 | 7351353 | 7 | 73513537 |
| GTIN-12 | 03600029145 | 2 | 036000291452 |
| GTIN-13 | 501234567890 | 0 | 5012345678900 |
| GTIN-14 | 1061414100041 | 5 | 10614141000415 |
About this barcode check digit calculator
This barcode check digit calculator computes the final digit of a UPC-A, EAN-13, EAN-8 or GTIN-14 barcode using the GS1 mod-10 algorithm. Paste the body digits — everything except the trailing check digit — and the tool returns the missing digit, the complete code, and a step-by-step breakdown of how the result was reached.
Use it whenever you need to calculate a GTIN check digit by hand, verify what a printed barcode should end with, or generate a fresh code from a body issued by your numbering authority.
When to Use It
- Generating a new EAN-13 from an issued 12-digit body before sending it to a label printer.
- Calculating a UPC check digit when a supplier sent you only the first 11 digits.
- Building a GTIN-14 carton code on top of an inner GTIN-13.
- Recomputing a check digit after correcting a typo in the body.
- Teaching a teammate how the GS1 mod-10 algorithm actually works.
How It Works
- Pick a format Choose GTIN-8/12/13/14, or leave Auto-detect on and we'll pick by length.
- Paste the body Enter the digits without the check digit. Spaces, dashes and dots are stripped.
- We weight each digit Walking from right to left, odd positions get ×3, even positions get ×1.
- We sum and round up The weighted sum is rounded up to the next multiple of 10.
- You get the check digit The difference between the rounded value and the sum is your check digit. Copy the full code in one click.
What to Avoid
- Pasting the full barcode including the existing check digit — use the GTIN Validator for that.
- Mixing UPC-A and UPC-E lengths — UPC-E needs to be expanded first.
- Trusting hand-computed digits without re-verifying; one digit off cascades through the whole code.
- Treating the calculator as a product database — it doesn't look up names or prices.
- Generating a GTIN body yourself; bodies must come from a GS1-assigned prefix.
Tips & Tricks
- If Auto-detect picks the wrong format, switch the dropdown to the format you intend.
- Click an example below to see the full step-by-step breakdown instantly.
- When the sum is already a multiple of 10, the check digit is 0 — not 10.
- For ITF-14, the leading 'indicator digit' (1–8) is part of the body and is weighted ×3.
- Pair this with the GTIN Validator to confirm an existing code after you've calculated the check digit.
GS1 Check Digit Calculator
This check digit calculator uses the GS1 standard mod-10 method, the same one GS1 specifies for GTINs, GLNs and SSCCs.
It accepts GTIN bodies of 7, 11, 12 or 13 digits. A GLN body has 12 digits like a GTIN-13 body, so GTIN-13 mode gives its check digit, while a 17-digit SSCC body is rejected.
Used as a UPC check digit calculator it takes 11 digits, and as an EAN check digit calculator 12 digits for EAN-13 or 7 for EAN-8. For a code that already ends in its check digit, use the GTIN validator instead.
GTIN Calculator for GTIN-8 to GTIN-14
As a GTIN check digit calculator it also builds a case-level GTIN-14 from an item's GTIN:
- Drop the item's check digit, and pad a UPC-A body with a leading 0.
- Put an indicator digit from 1 to 8 in front.
- Enter the 13-digit body in GTIN-14 mode.
The check digit always changes, because the indicator adds three times its value to the weighted sum. The UPC-A 614141000418 with indicator 1 becomes the GTIN-14 10614141000415.
How to Calculate a Check Digit by Hand
Weight the body digits 3 and 1 alternately, starting with 3 on the right, add the products, and subtract the total from the next multiple of 10. For the EAN-8 body 7351353:
- Weights from the left: 3, 1, 3, 1, 3, 1, 3.
- Products: 21, 3, 15, 1, 9, 5, 9, for a sum of 63.
- 70 − 63 = 7, so the full EAN-8 is 73513537.
Counting from the left, the first digit of a 7-, 11- or 13-digit body is weighted 3, but the first digit of a 12-digit body is weighted 1. To check a finished code, start with 1 on the check digit; the total must end in 0. The check digits explained guide covers why this catches typos.
Frequently Asked Questions
How does a barcode check digit calculator work?
It applies the GS1 mod-10 algorithm: multiply each body digit by 3 or 1 in an alternating pattern (counted from the right of the body), sum the results, then pick the digit that brings the total up to the next multiple of 10. The result is appended to the body to form the complete barcode.
Which Formats Does This Calculator Support?
UPC-A (GTIN-12), EAN-13 (GTIN-13), EAN-8 (GTIN-8) and ITF-14 (GTIN-14). All four share the same mod-10 algorithm — only the body length differs.
What Do I Paste — the Full Barcode or Just the Body?
Just the body, without the trailing check digit. For UPC-A that's 11 digits, for EAN-13 it's 12, for EAN-8 it's 7, for GTIN-14 it's 13. In Auto-detect mode the calculator picks the format from the length you entered.
Can I use this as an EAN-13 check digit calculator?
Yes. Pick GTIN-13 / EAN-13 (or use Auto-detect) and paste the first 12 digits. The 13th digit shown in the result is the EAN-13 check digit.
Does It Work for UPC-E?
UPC-E codes are derived from a UPC-A. Calculate the UPC-A check digit here using the 11-digit body; the UPC-E carries that same check digit. The UPC Lookup tool expands a UPC-E back to its UPC-A if you need the body.
Are My Numbers Sent to a Server?
No. The calculation runs entirely in your browser. Nothing is uploaded, logged or stored.
What Digit Is the Check Digit?
It is the last digit of the number: the 12th digit of a UPC-A, the 13th of an EAN-13, the 8th of an EAN-8 and the 14th of a GTIN-14. It is printed at the right end of the human-readable line and encoded in the bars like the other digits. This calculator returns it from the digits that come before it.
Can I Calculate an SSCC Check Digit?
Not with this calculator, which only accepts GTIN body lengths and rejects the 17 digits of an SSCC body. The SSCC uses the same GS1 mod-10 method, so the by-hand steps on this page work: weight the 17 digits 3 and 1 from the right, starting with 3, and close the sum to the next multiple of 10. The result is the 18th digit.
Is There a Check Digit Calculator for Excel?
This tool has no Excel add-in or export, but a spreadsheet formula can do the same math. Keep the body as text so leading zeros stay, pull out each digit with MID, weight it 3 or 1 from the right, add the products with SUMPRODUCT, and finish with MOD(10 - MOD(sum, 10), 10). Test the formula against a few results from this page before using it on a whole column.