A letter and an operator that look nearly the same, distinguished by whether the right-hand stroke closes.
Alpha is a Greek letter and stands for a quantity — an angle, a coefficient, a significance level. The proportionality sign is an operator and stands between two quantities to say they keep a constant ratio. The drawings differ in that the proportionality sign's right-hand stroke runs out in an open curve rather than closing into the letter's tail.
The proportionality sign is drawn like an alpha whose right-hand stroke has been opened out, and the two are separate characters that a reader can easily take for one.
Drawn from the visual attributes recorded for each symbol. Only traits the two records disagree about are listed.
| Trait | Alpha | Proportional-to sign |
|---|---|---|
| Built from | letter like and abstract | abstract and letter like |
| Alpha | Proportional-to sign | |
|---|---|---|
| What it is | A letter naming a quantity | An operator relating two quantities |
| Where it sits | In place of a value | Between two values |
| Code point | U+03B1 GREEK SMALL LETTER ALPHA | U+221D PROPORTIONAL TO |
| Shape | A loop closing into a descending tail | A loop running out into an open curve |
| Relationship (from Symbolwise's records) | Commonly confused with Proportional-to sign — The proportionality sign is drawn like an alpha whose right-hand stroke has been opened out, and the two are separate characters that a reader can easily take for one. | Commonly confused with Alpha — The proportionality sign is drawn like an alpha with its right stroke opened out. |
Wikipedia · retrieved 2026-07-31
Tertiary reference. Used for the widely-agreed uses of the letter across fields and for its history. Not used to assert that any one use is the letter's definitive meaning — no body defines that, and the record says so.
Unicode Code Chart: Mathematical Operators (U+2200–U+22FF)
The Unicode Consortium · retrieved 2026-07-30
Authoritative for the character's code point, name and block only. Unicode assigns identity; it does not define what a symbol means in use.
Glossary of mathematical symbols
Wikipedia · retrieved 2026-07-31
Tertiary reference. Used for what the notation means in ordinary mathematical practice and for attribution of its introduction, not for a claim that any body defines it.
The becquerel counts nuclear decays — one per second — and says nothing about harm. The sievert weights absorbed energy by the kind of radiation delivering it, and so estimates biological effect. A becquerel of one isotope and a becquerel of another can carry very different risk, which is exactly why exposure limits and medical doses are stated in sieverts and never in becquerels.
Look at what follows. A prefix never stands alone — it is glued to a unit symbol, as in kW or kg. A constant stands by itself in an equation. Careful physical writing subscripts the constant as k_B for exactly this reason, and the kelvin's capital K is a third claimant to the same letter.
Equal-length lines mean a capacitor. Alternating long and short lines mean a battery, with the long line positive. If the second line is curved rather than straight it is a polarised capacitor — still a capacitor, but one that must be fitted the right way round.
Length is the tell. A crescendo hairpin is drawn long, below a stave, and spans the passage it applies to — its extent *is* the instruction. A less-than sign is one character wide and sits between two values. If it stretches, it is music; if it fits between two numbers, it is mathematics.