There are standard
rules for converting an ISBN-10 into an ISBN-13.
Review the
information
below for a complete understanding of these conversion rules.
Converting the 10-digit ISBN to the Bookland EAN Code
1) Drop the check digit (the last
digit) from your existing ISBN-10.
For example, your ISBN-10 is 0-940016-73-7. By
dropping the check digit (7), you get a 9-digit number, 0-940016-73.
2) Add the prefix '978' to the beginning of your
9-digit number.
Your 9-digit
0-940016-73 now becomes 12 digits, 978-0-940016-73.
3) Recalculate your check digit using the modules 10
check digit routine.
The
modules
10 check digit routine
is the current routine used to calculate the check digit for the Bookland EAN.
Here’s how, using the calculations shown in Table
1-1.
Table 1-1 The 10-digit /
13-digit ISBN-13 Conversion Chart
|
ISBN = |
9 |
7 |
8 |
0 |
9 |
4 |
0 |
0 |
1 |
6 |
7 |
3 |
|
Weighting Factors |
1 |
3 |
1 |
3 |
1 |
3 |
1 |
3 |
1 |
3 |
1 |
3 |
|
Values (product) |
9 + |
21 + |
8 + |
0 + |
9 + |
12 + |
0 + |
0 + |
1 + |
18 + |
7 + |
9 = 94 |
Using the 12-digit number from Step 2 (shown in Table
1-1), multiply each digit by the weighting factor shown beneath it in
Table 1-1. In this example, you have (9x1) + (7x3) +
(8x1) + (0x3)...and so on.
Add the
resulting values together. The sum of the values equals 94.
Divide the sum by the modulus (which is always 10).
Divide 94
by 10. Your result is 9, with a remainder of 4.
Using the
standard modulus (10), subtract the remainder from 10 to get the check
digit (last digit). In this example, 10 minus 4 equals the
check digit of 6.
Add the
check digit to the end of the 12-digit number created in Step 2. The
conversion from a 10-digit ISBN to a 13-digit ISBN is complete.
The ISBN-13
becomes 978-0-940016-73-6.
Notes:
There is one exception to this formula: whenever the remainder is zero
(0), the check digit is always zero (0) as well.
The algorithm for checking an ISBN-13 beginning with '979' is the same
as the algorithm for ISBN-13s beginning with '978'. To validate any
ISBN-13, drop the given check digit, recalculate it, and compare the
result of the new calculation to the original check digit. If they
match, the number is a valid ISBN-13. The same algorithm applies to any
13-digit EAN product identifier worldwide.
Algorithm for Checking
the Bookland EAN
a.
Assign the
constant weighting factors associated with each position in the EAN.
Multiply each digit by its associated weighting factor and add together
(e.g. 9780901 69066 1).
| Weighting Factors |
1 |
3 |
1 |
3 |
1 |
3 |
1 |
3 |
1 |
3 |
1 |
3 |
1 |
| Bookland EAN |
9 |
7 |
8 |
0 |
9 |
0 |
1 |
6 |
9 |
0 |
6 |
6 |
1 |
| Values |
9+ |
21+ |
8+ |
0+ |
9+ |
0+ |
1+ |
18+ |
9+ |
0+ |
6+ |
18+ |
1=100 |
c. Divide the sum by 10 and the
result must be a whole number with no remainder.
Retrieving
the 10-digit ISBN from the Bookland EAN
('978' format only)
1) Remove the prefix *978* and the
check digit (last digit) from the EAN.
You are left with
a nine-digit number. For example, EAN 9780940016610 becomes
094001661.
2)
Recalculate the check digit.
The algorithm for this
process follows.
Algorithm for
calculating the check digit for a 10-digit ISBN
Using the 9-digit number from Step 1 above, multiply each
digit by the weighting factor shown in the table below.
In this example, you have (10x0) + (9x9) + (8x4) + (7x0)...and so
on.
| Weighting Factors |
10 |
9 |
8 |
7 |
6 |
5 |
4 |
3 |
2 |
| Bookland EAN |
0 |
9 |
4 |
0 |
0 |
1 |
6 |
6 |
1 |
| Values |
0+ |
81+ |
32+ |
0+ |
0+ |
5+ |
24+ |
18+ |
2=162 |
b.
Add the resulting values together.
The sum of the values equals 162.
Divide the sum by 11. For
example, 162 ÷ 11 = 14 with a remainder of 8.
Subtract the remainder, if any, from 11.
The result is the check digit. In this case,
11 minus 8 equals 3. Therefore, the 10-digit ISBN check digit is
3.
Add the check digit to the end of the 9-digit number created in Step
1. The conversion from a 13-digit ISBN to a 10-digit ISBN is complete.
The 10-digit ISBN becomes 0-940-01661-3.
Note:
If the result is “0”, the check digit is “0”. If the value of
the check digit is 10, that should be represented by the roman X.
