Congruent symbol (≅)
≅ means “is congruent to”: two figures are congruent when they are the same shape and the same size, so one could be laid exactly on the other. △ABC ≅ △DEF says the two triangles are exact copies.
Easily confused with
How to read it
Henry Africk’s Elementary College Geometry (CUNY) calls two triangles congruent if one can be placed over the other so that they coincide, exact copies of each other, and gives ≅ as the symbol. OpenStax’s Contemporary Mathematics uses ≅ for sides as well as triangles: if DF ≅ RT, EF ≅ ST and DE ≅ RS, the triangles DEF and RST are congruent. The order of the letters matters in Africk’s book: △ABC ≅ △DEF means A matches D, B matches E and C matches F. Africk warns that not every textbook keeps to this, and when the letters are written in any order the statement no longer tells you which parts correspond.
Also searched as: ≅, ≇, congruence symbol, congruent sign, equal sign with a squiggle, not congruent.
≅ in Unicode
Unicode’s name for the character is APPROXIMATELY EQUAL TO (U+2245), which is not its geometry meaning, and its crossed-out form ≇ (U+2247) is NEITHER APPROXIMATELY NOR ACTUALLY EQUAL TO. The usual sign for “approximately equal” is a different one, the double wavy ≈.
Congruent or similar?
Similar figures (∼) have the same shape but may differ in size; congruent figures have the same shape and the same size. The extra lines in ≅ are the equals sign for the size.
Read next
- Next in Geometry symbolsSimilar symbol (∼)∼ means “is similar to”: two figures are similar when they have the same shape, with equal angles, though not necessarily the same size. △ABC ∼ △DEF says one triangle is a scaled copy of the other.
- Leibniz built ≅ from ∼ and =.Equals sign (=)The equals sign (=) means the two sides have the same value. a = b is read “a is equal to b”.
More geometry symbols
The same shape elsewhere
Browse symbols drawn with curves and waves or lines.
Sources
- Elementary College Geometry, 2.1 The Congruence Statement, Henry Africk, Elementary College Geometry (CUNY New York City College of Technology, 2021), CUNY Academic Works, via LibreTexts, The congruence statement
- Contemporary Mathematics, 10.3 Triangles, OpenStax (Rice University), Congruence
- Earliest Uses of Symbols from Geometry, Jeff Miller, Earliest Uses of Various Mathematical Symbols, MacTutor History of Mathematics, University of St Andrews, Congruence
- A History of Mathematical Notations, Vol. I: Notations in Elementary Mathematics, Florian Cajori (Chicago: Open Court, 1928); full text of the Wellcome Collection copy, Internet Archive, § 372 Signs for similarity and congruence
- Mathematical Operators: Range 2200–22FF (code chart), The Unicode Standard, Version 18.0, Unicode Consortium, Relations, 2245–2247
Researched, edited and approved by Rory Hansen before publishing. Last reviewed October 9, 2026. How we research
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