Flat icons are the most widely used style in modern UI design — clean shapes, solid fills, no shadows or gradients. They're simple to prompt for once you know the right vocabulary.
What Are Flat Icons?#
Flat icons use solid colors, simple geometric shapes, and minimal detail. There are no drop shadows, no gradients (unless intentional), no bevels. The style is often associated with Google's early Material Design and Apple's iOS 7 redesign — clean, two-dimensional, immediately readable at small sizes.
Key Prompt Keywords#
| Keyword | Effect |
|---|---|
flat style | Core signal — tells the model to avoid depth and shadows |
solid fill | Reinforces flat look, suppresses gradients |
2D | Explicitly removes any 3D rendering |
minimal | Reduces unnecessary detail |
clean lines | Encourages crisp, simple shapes |
vector style | Implies clean outlines and solid fills |
no shadow | Explicitly removes drop shadows |
bold | Makes shapes thicker and more readable |
Good vs Bad Prompt Examples#
Example 1: House icon#
Weak: a house icon
Strong: a house, flat style, solid fill, blue and white, minimal
The weak prompt will likely produce a photorealistic or 3D house. The strong prompt locks in the flat style with solid color.
Example 2: Lightning bolt#
Weak: lightning bolt, simple
Strong: a lightning bolt, flat style, yellow, bold, vector style
"Simple" is ambiguous — it could mean outline, hand-drawn, or minimal. "Flat style, vector style" gives the model clear direction.
Example 3: Envelope / email#
Weak: email icon, modern
Strong: an envelope, flat style, 2D, solid teal fill, clean lines, no shadow
"Modern" is meaningless without context. Specifying 2D, solid teal fill, and no shadow removes ambiguity entirely.