How the notches add up
This is the Universal ear-notching system, also called the 1-3-9 system. The pig’s right ear gives the litter number and its left ear the pig number. On the right ear, the bottom edge has 1 near the head and 3 near the tip, the top edge has 9 near the tip and 27 near the head, and a notch in the tip is 81. The left ear has 1, 3 and 9 in the same places. Add the notches in each ear, and write the litter first.
Each section holds one or two notches, the 81 tip only one, so litters run to 161 and pigs to 26. Every pig here is drawn fresh from a set code, and the key is worked out from the rules, so a class link always shows the same pigs.
Six ways to practice
- Read the notches: write each pig’s litter and pig number.
- Notch the ears: tap the sections for a given number, or draw the Vs on paper.
- Littermates: find the pigs in a pen that share pig A’s litter.
- Rule breakers: the pig notched against the rules, or the number that cannot be made.
- Find the mistake: the records say one number, the ears show another.
- Largest numbers: the limits of the system, and the fewest notches for a number.
Level 1 prints the section values beside the ears. Level 2 marks only the right and left ear. Level 3, the show ring, drops every label, and some pigs face you while others are seen from behind, so you have to work out which ear is the pig’s right.
A worked example
In set KKQ332, pig 1’s right ear has a notch in the tip, one on the top edge near the tip and two on the bottom edge near the head: 81 + 9 + 1 + 1 = 92. Its left ear has one notch on the top edge: 9. The pig is 92-9. Open set KKQ332
Questions
How do you read pig ear notches?
Add up the notches in the pig's right ear for the litter number, then the left ear for the pig number, and write them with a dash, litter first. A pig with 27, 9, 1 and 1 in the right ear and 3 and 1 in the left is 38-4.
Which ear is the litter number?
The pig's own right ear. When the pig faces you it is the ear on your left; from behind it is on your right. Every pig in a litter has the same right ear, and the left ear tells littermates apart.
What is the largest litter number you can ear notch?
161: one notch in the 81 tip plus two each in the 27, 9, 3 and 1 sections. The left ear has only 1, 3 and 9, so pig numbers go up to 26.
Can one section have two notches?
Yes, two at most, and both count: two notches in the 3 section make 6. The 81 tip takes only one. The National Swine Registry allows no more than two notches in a section, so three is a mistake.
Why is it called the 1-3-9 system?
Each section is worth three times the one before it: 1, 3, 9, 27, then 81. With up to two notches in each, every number has exactly one way to be notched, so a key never has two right answers.
What is the hatched band on the ears?
The middle of each edge, where a notch could pass for either section: a 1 or a 3, a 9 or a 27. NMSU shades it on its chart and UNL warns against notching there.
When do litter numbers start over?
The National Swine Registry asks breeders to number litters in birth order from 1, starting again each January 1 and July 1, and to notch the litter in the right ear before pigs are seven days old.
How do I use this with a 4-H club or class?
Pick a task and level, then Share with class: everyone who opens the link gets the same pigs and can check their own answers. To stop copying on paper, print a class set: each student gets different pigs, and the keys print after the worksheets.
Sources, read October 26, 2026: NJSA and National Swine Registry, Ear Notching presentation and quiz (PDF); NSR application for registration, with the ear notching key (PDF); UNL NebGuide G1880, Proper Way to Ear Notch Pigs; NMSU Guide B-602, Identify Pigs by Ear Notching; K-State Universal Ear-Notching System chart (PDF); Certified Pedigreed Swine, Ear Notching.