The History of the % Symbol

From Latin to Italian to a single sign

The concept of expressing values as fractions of 100 dates back to ancient Rome, where taxes and interest rates were often quoted “per centum” (per hundred). Even before the symbol % existed, traders wrote out the full phrase.

In medieval Italian commerce, “per cento” was so common that scribes started abbreviating it as “p cento”, then “p c⁰” with the “cento” stacked above the “c”. By the 15th century, manuscripts show this stacked form gradually morphing.

The 17th century shift

By the 1600s, the stacked form had reduced to a horizontal line with two zeros: roughly °⁄°. By the 1700s, the diagonal slash had replaced the horizontal line, giving us the modern %.

Per mille and basis points

The same compression produced two related signs:

• ‰ per mille (per thousand) — for finer ratios
• ‱ per myriad (per ten thousand) — same as a basis point in finance

Modern usage

The percent sign is universal across mathematical notation in essentially every language and writing system, though the surrounding word varies:

• English: percent / per cent
• French: pour cent
• German: prozent
• Spanish: por ciento
• Japanese: パーセント (pāsento) — borrowed from English

In computer programming

The % character has a second life as the “modulo” operator in C, Java, Python, JavaScript, and most other languages. 17 % 5 = 2 in code, not 17/5 × 100 = 340. Same symbol, completely different meaning — context matters.