143 means "I love you". Count the letters in each word: I has 1, love has 4, you has 3. Send someone 143 and you've said the whole sentence in three digits.
It is the oldest of the number codes, and the one people mean when they text it today. The others, 1432, 459 and 831, are the same idea with different arithmetic.
143, 1432, 459, 831 and 520
- 143. I love you. A letter count: 1, 4, 3.
- 1432. I love you too. The same count with a 2 on the end for "too". It's what people send back when someone sends 143.
- 459. I love you, spelled on an old phone keypad. The letters I, L and Y sit on the 4, 5 and 9 keys.
- 831. I love you again. Eight letters, three words, one meaning.
- 520. I love you in Mandarin. The sound of 五二零 (wu er ling) is close to 我爱你 (wo ai ni). It's the one that isn't about English at all.
If you've landed here from a search for "I miss you", the other explainer on this site covers why none of these codes mean that.
Where it came from
It's usually traced to pagers in the 1990s. A pager could show digits and nothing else, so people agreed what the numbers meant and sent short codes instead of words. 143 was one of them, and it moved to text messages when texting replaced pagers.
Nobody can say who sent the first one. What survived is the habit, and the reason is easy to see: three digits are quicker to send than a sentence, and easier to send when you aren't sure how the sentence will land.
The count fits other phrases too
Count the letters in "I miss you": 1, 4, 3. "I need you" and "I hate you" do the same. Nothing in the number says which one you meant, so the meaning comes entirely from the habit. In practice 143 only ever means love, and a sender who wants to say anything else writes it out.
Who it suits
It reads as warm and a little playful. That works for a partner, a close friend, a sibling, a cousin or a grandchild texting a grandparent. From a crush, it's a bigger step than it looks, since it says love in a way you can later call a joke. From a colleague, it will confuse you both.
It's also a way into a feeling you haven't quite said yet. Some people use 143 for months before the full sentence. If that's you, you're in a long tradition.
How to reply
- 1432. The classic, and exactly the right size.
- I love you too. Spelled out, which can feel like more. Good when you mean it.
- 143 back. Fine between people who text this way, a little flat otherwise.
If you aren't sure how you feel, "Thank you, that made my day" is honest and kind. You don't owe a number back.
Where to go from here
- I miss you full form the other half of the question, and why none of these codes mean it
- Love messages for when three digits aren't enough
- Miss you messages for when you mean that instead