MICR stands for Magnetic Ink Character Recognition. It is the line of numbers and symbols printed along the bottom of a check in the E-13B font, using magnetic ink or toner. It holds the routing number, account number and check number, and it lets bank machines read and sort checks quickly and accurately.
If you have ever looked closely at the bottom of a check, you have seen it: blocky digits with odd little symbols between them. This page explains what each part means, why the technology exists, how to check a routing number and why it matters when you print your own checks.
What does the MICR line say?
Reading left to right, a US check's MICR line usually carries three pieces of information. The exact order varies. On many business checks the check number comes first, on many personal checks it comes last.
- The routing number (also called the transit number): nine digits between two transit symbols, identifying your bank.
- The account number: identifies your account at that bank, followed by the on-us symbol.
- The check number: matches the number printed in the top right corner of the check.
After a check is deposited, the bank also encodes the amount in magnetic ink at the far right, in the amount field. That is added later, not by you. For the meanings of the individual numbers, see what is a routing number, what is an account number on a check and what is a check number.
What are the four MICR symbols?
The E-13B font has fourteen characters: the digits 0 to 9, and four special symbols that act like punctuation for machines.
| Symbol | Name | What it does |
|---|---|---|
| Transit symbol | Brackets the nine-digit routing number | Marks where the routing field starts and ends |
| On-us symbol | Follows the account number (and sometimes sits between parts of it) | Marks fields that belong to the paying bank |
| Amount symbol | Brackets the amount field | Added by the bank when the check is processed |
| Dash symbol | Sits between parts of a number | Separates parts of an account or serial number |
These symbols do not look like letters, and they are not in a normal font. A word processor does not have them unless you install an E-13B font, which is one reason a regular Word document cannot create a proper MICR line.
Why do banks use magnetic ink?
The system was developed in the 1950s, when banks needed to sort huge numbers of paper checks quickly. Printing the key numbers in magnetic ink in a standard shape let machines read them by passing the check under a magnetic read head. Each character was designed so that it produces a distinct signal as it moves past the head, which makes the reading reliable even when the paper is dirty, stamped or scribbled on.
That reliability is the point. The same E-13B standard is still used in the US today. Some other countries use a different MICR font called CMC-7.
How can you verify a routing number?
A US routing number has nine digits, and the last digit is a checksum. Multiply the digits by the repeating weights 3, 7, 1, 3, 7, 1, 3, 7, 1 and add the results. The total must be a multiple of 10.
Take 123456780 as an example number built to pass the test: 3x1 + 7x2 + 1x3 + 3x4 + 7x5 + 1x6 + 3x7 + 7x8 + 1x0 = 3 + 14 + 3 + 12 + 35 + 6 + 21 + 56 + 0 = 150. Since 150 is a multiple of 10, it passes. A number that fails is mistyped or invalid. The checksum cannot tell you whether a real bank owns the number, only whether it is well formed. A lookup tool such as the one in Check Writer 123 also suggests the bank name.
Does a check still need MICR in the age of images?
Many banks now process checks largely as images, so the physical magnetic reading is less central than it once was. But the MICR line still tells systems which bank and account to charge, and it is a standard part of a check. A check with a missing or poorly printed line is likelier to be flagged for manual handling.
What happens without proper MICR varies. Some banks repair or re-key the line and charge nothing. Others return the item, charge a fee, or delay it. A teller may refuse a deposit if the line looks wrong. This is a bank-by-bank matter, so confirm with yours instead of assuming a non-magnetic check will always go through.
How is MICR printed?
Printers use one of three common approaches.
- Pre-printed check stock: a check printer prints the MICR line in magnetic ink when the stock is made. You then print the variable fields.
- Laser printing with MICR toner: the toner contains magnetic particles. It is used in a laser that supports it, on blank stock, to print the full check including the line.
- Non-magnetic printing: standard toner or inkjet ink prints the same characters but not in magnetic form. Acceptance depends on the bank, and magnetic ink is the safest option for high volume.
If you use blank stock, the font, size and position all matter. The line sits in a defined band near the bottom edge, and the characters must be the right shape and in the right place. A small shift can cause a reader to misread. If yours looks off, MICR line doesn't print correctly covers the usual causes, and how to print a check with MICR information covers the setup.
Common MICR mistakes
- Using a regular font rather than E-13B, so the symbols are wrong or missing.
- Typing the routing and account numbers in the wrong order or with a typo.
- Printing the line too high or too low so it overlaps a perforation or another field.
- Printing with Fit to page selected, which scales the characters and shifts the position.
- Smearing a line printed with ordinary ink before it has dried.
- Not verifying the routing number checksum before printing a full run.
On 3-to-a-page blank check stock, Check Writer 123 prints the whole check including the MICR line, and it lets you move the MICR line separately with its alignment tool. Whether a bank accepts the result is up to the bank, so confirm before you depend on it.
Putting it together
MICR is the machine-readable core of a check: routing number, account number, check number and a few symbols in a special magnetic font. Whether you order checks or print them, make sure the numbers are correct and the line is clean. The legal and practical overview for self-printing is in can you print your own checks.