Flatness tolerance symbol

A parallelogram, specifying how flat a surface must be.

Also known as: Flatness, Leaning rectangle, Parallelogram drawing symbol

Engineering & technicalStandard profile

Meanings

A leaning parallelogram means flatness. It requires the surface to lie between two parallel planes a stated distance apart, and it needs no datum because flatness is a property of the surface alone.

Common modern usageVerified fact
Requires every point of a surface to lie between two parallel planes separated by the stated tolerance.
Contexts: Technical drawing
Common modern usageVerified fact
Needs no datum reference, because flatness is a property of the surface in itself rather than a relationship to anything else.
Contexts: Technical drawing

Visual description

A parallelogram with horizontal top and bottom edges and sides slanting to the right, drawn inside the leftmost cell of a tolerance frame.

Symmetry: point
Orientation: rotated

Part of the same system as: Perpendicularity tolerance symbol
Geometric characteristic symbols placed in a tolerance frame.

Confidence

IdentityModerate confidence: Moderate confidence because the identity is documented in encyclopedic references, but only a single source has been found so far.
Historical originLow confidence: Low confidence because the historical origin is documented in encyclopedic references, but only a single source has been found so far, but early or supporting evidence is limited, but the regional or cultural match to this specific claim is not precise.
Current useModerate confidence: Moderate confidence because the current use is documented in encyclopedic references, but only a single source has been found so far.
Visual matchModerate confidence: Moderate confidence because the visual match is documented in encyclopedic references, but only a single source has been found so far.

Sources

Geometric dimensioning and tolerancing
Wikipedia · retrieved 2026-08-01
Tertiary reference. Used for what a symbol instructs and which standard governs it. Where a standard is named it is reported by this source rather than read, so no meaning is typed `official` on that basis.

Last reviewed 2026-07-31

Part of

Technical drawing notation

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Meanings

A leaning parallelogram means flatness. It requires the surface to lie between two parallel planes a stated distance apart, and it needs no datum because flatness is a property of the surface alone.

Common modern usageVerified fact

Requires every point of a surface to lie between two parallel planes separated by the stated tolerance.

Contexts: Technical drawing

Common modern usageVerified fact

Needs no datum reference, because flatness is a property of the surface in itself rather than a relationship to anything else.

Contexts: Technical drawing

Confidence

IdentityModerate confidence: Moderate confidence because the identity is documented in encyclopedic references, but only a single source has been found so far.
Historical originLow confidence: Low confidence because the historical origin is documented in encyclopedic references, but only a single source has been found so far, but early or supporting evidence is limited, but the regional or cultural match to this specific claim is not precise.
Current useModerate confidence: Moderate confidence because the current use is documented in encyclopedic references, but only a single source has been found so far.
Visual matchModerate confidence: Moderate confidence because the visual match is documented in encyclopedic references, but only a single source has been found so far.

Sources

Geometric dimensioning and tolerancing
Wikipedia · retrieved 2026-08-01
Tertiary reference. Used for what a symbol instructs and which standard governs it. Where a standard is named it is reported by this source rather than read, so no meaning is typed `official` on that basis.

Last reviewed 2026-07-31

Meanings

Visual description

Related & commonly confused symbols

Meanings

Visual description

Related & commonly confused symbols