Fonts and Text

Dear ImGui provides a powerful and flexible font system supporting TTF/OTF fonts, icon fonts, Unicode, and dynamic font sizing.

New in 1.92 (June 2025): Fonts now support dynamic sizing! You can change font size at runtime without pre-loading multiple sizes. Glyph ranges are also automatic with updated backends.

Quick Start

Using Default Font

// Dear ImGui embeds a default font automatically
ImGui::Text("Hello, World!"); // Uses default font

Setting Base Font Size

ImGuiStyle& style = ImGui::GetStyle();
style.FontSizeBase = 18.0f;  // Set default size for all fonts

Loading Custom Fonts

Basic Font Loading

Since 1.92 (with updated backend):

ImGuiIO& io = ImGui::GetIO();

// Load TTF/OTF font (size is optional)
ImFont* font = io.Fonts->AddFontFromFileTTF("fonts/Roboto-Medium.ttf");

// Load with specific size
ImFont* font = io.Fonts->AddFontFromFileTTF("fonts/arial.ttf", 16.0f);

Before 1.92 (or without updated backend):

ImGuiIO& io = ImGui::GetIO();

// Size parameter is required
ImFont* font = io.Fonts->AddFontFromFileTTF("fonts/Roboto-Medium.ttf", 18.0f);

Loading Multiple Fonts

ImGuiIO& io = ImGui::GetIO();

// Load different fonts
ImFont* font_regular = io.Fonts->AddFontFromFileTTF("Roboto-Regular.ttf");
ImFont* font_bold = io.Fonts->AddFontFromFileTTF("Roboto-Bold.ttf");
ImFont* font_mono = io.Fonts->AddFontFromFileTTF("RobotoMono-Regular.ttf");

// Use them in your UI
ImGui::Text("Regular text");
ImGui::PushFont(font_bold, 0.0f);  // Keep current size
ImGui::Text("Bold text");
ImGui::PopFont();

Using Fonts

Changing Active Font

ImFont* my_font = /* previously loaded font */;

// Change font and keep current size
ImGui::PushFont(my_font, 0.0f);
ImGui::Text("Text in custom font");
ImGui::PopFont();

// Change font AND size
ImGui::PushFont(my_font, 24.0f);
ImGui::Text("Large text in custom font");
ImGui::PopFont();

// Change only size (keep current font)
ImGui::PushFont(NULL, 32.0f);
ImGui::Text("Large text");
ImGui::PopFont();

Dynamic Font Sizing (1.92+)

// Change size at runtime without pre-loading
static float font_size = 16.0f;
ImGui::SliderFloat("Font Size", &font_size, 8.0f, 48.0f);

ImGui::PushFont(NULL, font_size);
ImGui::Text("Dynamically sized text!");
ImGui::PopFont();

Font size parameter changes in 1.92:

Before 1.92: PushFont(font) used the size passed to AddFontXXX()
Since 1.92: PushFont(font) requires explicit size parameter
Use PushFont(font, font->LegacySize) to match old behavior

Font Configuration

Advanced Font Options

ImFontConfig config;
config.OversampleH = 2;              // Horizontal oversampling (default: 2)
config.OversampleV = 1;              // Vertical oversampling (default: 1)
config.GlyphMinAdvanceX = 13.0f;     // Minimum advance (for monospace)
config.GlyphExtraSpacing = ImVec2(0.0f, 0.0f); // Extra spacing
config.PixelSnapH = true;            // Align to pixel grid

ImFont* font = io.Fonts->AddFontFromFileTTF("font.ttf", 16.0f, &config);

Merging Fonts

Combine multiple fonts into one:

// Load base font
ImFont* font = io.Fonts->AddFontFromFileTTF("Roboto-Regular.ttf");

// Merge additional fonts into base font
ImFontConfig config;
config.MergeMode = true;

// Add Japanese characters
io.Fonts->AddFontFromFileTTF("NotoSansCJK-Regular.ttf", 0.0f, &config);

// Add icons
io.Fonts->AddFontFromFileTTF("FontAwesome.ttf", 0.0f, &config);

// Now 'font' contains glyphs from all three fonts

Unicode Support

Using Unicode Text

// Use u8 prefix for UTF-8 string literals (C++11+)
ImGui::Text(u8"Hello 世界");        // Chinese
ImGui::Text(u8"こんにちは");         // Japanese
ImGui::Text(u8"Привет мир");        // Russian
ImGui::Text(u8"مرحبا بالعالم");    // Arabic

// Emoji support (requires IMGUI_USE_WCHAR32)
ImGui::Text(u8"😀 🎉 🚀");

Since 1.92: You don’t need to specify glyph ranges anymore with updated backends! Glyphs are loaded on-demand automatically.

Loading Fonts with Specific Ranges (Pre-1.92)

// Japanese
io.Fonts->AddFontFromFileTTF("NotoSansCJK.ttf", 18.0f, NULL, 
                              io.Fonts->GetGlyphRangesJapanese());

// Chinese Simplified (common characters)
io.Fonts->AddFontFromFileTTF("NotoSansCJK.ttf", 18.0f, NULL,
                              io.Fonts->GetGlyphRangesChineseSimplifiedCommon());

// Cyrillic
io.Fonts->AddFontFromFileTTF("font.ttf", 18.0f, NULL,
                              io.Fonts->GetGlyphRangesCyrillic());

// Korean
io.Fonts->AddFontFromFileTTF("font.ttf", 18.0f, NULL,
                              io.Fonts->GetGlyphRangesKorean());

Icon Fonts

Use icon fonts like FontAwesome for visual icons:

Setup

#include "IconsFontAwesome6.h"  // Get from IconFontCppHeaders

ImGuiIO& io = ImGui::GetIO();

// Load regular font
io.Fonts->AddFontFromFileTTF("Roboto-Regular.ttf");

// Merge icon font
ImFontConfig config;
config.MergeMode = true;
config.GlyphMinAdvanceX = 13.0f; // Make icons monospace
io.Fonts->AddFontFromFileTTF("FontAwesome6.ttf", 13.0f, &config);

Using Icons

// Use icon constants in strings
ImGui::Button(ICON_FA_FOLDER_OPEN " Open");
ImGui::Text(ICON_FA_SEARCH " Search");
ImGui::MenuItem(ICON_FA_SAVE " Save", "Ctrl+S");

// Icons in text
ImGui::Text("%s Found %d items", ICON_FA_CHECK, count);

Common Icon Font Libraries

Font Awesome - Popular icon set
Material Design Icons
IconFontCppHeaders - C++ headers for icon fonts

Loading Fonts from Memory

From Memory Buffer

// Load font data into memory
unsigned char* font_data = /* load from file/resource */;
size_t font_size = /* size in bytes */;

ImFontConfig config;
config.FontDataOwnedByAtlas = false; // Keep ownership of data
ImFont* font = io.Fonts->AddFontFromMemoryTTF(font_data, font_size, 
                                               18.0f, &config);

// You must keep font_data valid until RemoveFont() or atlas destruction

Embedded Compressed Font

// Use binary_to_compressed_c tool to generate this
extern const unsigned char my_font_compressed_data[];
extern const unsigned int my_font_compressed_size;

ImFont* font = io.Fonts->AddFontFromMemoryCompressedTTF(
    my_font_compressed_data, my_font_compressed_size, 16.0f);

Font Atlas

Atlas Configuration

ImFontAtlas* atlas = io.Fonts;

// Configure atlas texture
atlas->TexDesiredFormat = ImTextureFormat_RGBA32;  // or ImTextureFormat_Alpha8
atlas->TexGlyphPadding = 1;    // Padding between glyphs
atlas->TexMinWidth = 512;      // Minimum texture width
atlas->TexMaxWidth = 8192;     // Maximum texture width
atlas->TexMinHeight = 128;     // Minimum texture height
atlas->TexMaxHeight = 8192;    // Maximum texture height

Atlas Flags

enum ImFontAtlasFlags_
{
    ImFontAtlasFlags_None               = 0,
    ImFontAtlasFlags_NoPowerOfTwoHeight = 1 << 0,  // Don't round height to power of 2
    ImFontAtlasFlags_NoMouseCursors     = 1 << 1,  // Don't build mouse cursor textures
    ImFontAtlasFlags_NoBakedLines       = 1 << 2,  // Don't build thick line textures
};

atlas->Flags |= ImFontAtlasFlags_NoPowerOfTwoHeight;

Text Rendering

Measuring Text Size

const char* text = "Hello, World!";
ImVec2 text_size = ImGui::CalcTextSize(text);

printf("Text size: %.2f x %.2f\n", text_size.x, text_size.y);

// With wrapping
float wrap_width = 200.0f;
ImVec2 wrapped_size = ImGui::CalcTextSize(text, NULL, false, wrap_width);

Colored Text

// Using style colors
ImGui::TextColored(ImVec4(1.0f, 0.0f, 0.0f, 1.0f), "Red text");
ImGui::TextColored(ImVec4(0.0f, 1.0f, 0.0f, 1.0f), "Green text");

// Disabled text
ImGui::TextDisabled("This text is grayed out");

// Using PushStyleColor
ImGui::PushStyleColor(ImGuiCol_Text, IM_COL32(255, 255, 0, 255));
ImGui::Text("Yellow text");
ImGui::PopStyleColor();

Wrapped Text

// Auto-wrapped text
ImGui::TextWrapped("This is a long text that will automatically wrap "
                   "to fit the available width of the window.");

// Manual wrapping
ImGui::PushTextWrapPos(ImGui::GetCursorPos().x + 200.0f);
ImGui::Text("This text will wrap at 200 pixels from current position.");
ImGui::PopTextWrapPos();

DPI Scaling

Global DPI Scale (1.92+)

ImGuiStyle& style = ImGui::GetStyle();

// Set DPI scale for all fonts
style.FontScaleDpi = 2.0f;  // 200% scaling

// Scale all UI sizes
style.ScaleAllSizes(2.0f);

Per-Platform Scaling

#ifdef __APPLE__
    // macOS Retina display handled automatically in 1.92+
#elif defined(_WIN32)
    // Windows DPI scaling
    float dpi_scale = GetDpiForWindow(hwnd) / 96.0f;
    style.FontScaleDpi = dpi_scale;
    style.ScaleAllSizes(dpi_scale);
#endif

Troubleshooting

Blank Squares or Missing Glyphs

Ensure the font file includes the characters you need, or that glyphs are loading correctly.

Incorrect File Path

Use absolute paths or verify working directory. Use \\ or / for path separators.

Font Too Large for Atlas

Reduce oversampling, limit glyph ranges, or increase atlas max size.

UTF-8 Encoding Issues

Use u8"" prefix and ensure source files are UTF-8 encoded.

Debug Tools

// Show font atlas texture
ImGui::ShowMetricsWindow();
// Navigate to Fonts section to inspect loaded fonts and glyphs

// Verify UTF-8 encoding
ImGui::DebugTextEncoding(u8"こんにちは");

Complete Example

void SetupFonts()
{
    ImGuiIO& io = ImGui::GetIO();
    ImGuiStyle& style = ImGui::GetStyle();
    
    // Set base font size
    style.FontSizeBase = 16.0f;
    
    // Load primary font
    ImFont* font_regular = io.Fonts->AddFontFromFileTTF(
        "fonts/Roboto-Regular.ttf");
    
    // Load bold font
    ImFont* font_bold = io.Fonts->AddFontFromFileTTF(
        "fonts/Roboto-Bold.ttf");
    
    // Load monospace font
    ImFontConfig mono_config;
    mono_config.GlyphMinAdvanceX = 13.0f;
    ImFont* font_mono = io.Fonts->AddFontFromFileTTF(
        "fonts/RobotoMono-Regular.ttf", 0.0f, &mono_config);
    
    // Merge icon font
    ImFontConfig icon_config;
    icon_config.MergeMode = true;
    icon_config.GlyphMinAdvanceX = 16.0f;
    io.Fonts->AddFontFromFileTTF("fonts/FontAwesome6.ttf", 16.0f, &icon_config);
    
    // Store font pointers for later use
    g_FontRegular = font_regular;
    g_FontBold = font_bold;
    g_FontMono = font_mono;
}

void ShowFontDemo()
{
    ImGui::Begin("Font Demo");
    
    ImGui::Text("Default font");
    
    ImGui::PushFont(g_FontBold, 0.0f);
    ImGui::Text("Bold font");
    ImGui::PopFont();
    
    ImGui::PushFont(g_FontMono, 0.0f);
    ImGui::Text("Monospace: int main() { return 0; }");
    ImGui::PopFont();
    
    ImGui::PushFont(NULL, 24.0f);
    ImGui::Text("Large text");
    ImGui::PopFont();
    
    ImGui::Text(ICON_FA_FOLDER " Folder " ICON_FA_FILE " File");
    
    ImGui::End();
}

Reference

FONTS.md documentation
ImFontAtlas API (line 3600+)
Icon Font Headers
Font atlas visualization in Metrics/Debugger window

Getting Started

Core Concepts

Widgets

Advanced Features

Backends

Styling

Guides

​Fonts and Text

​Quick Start

​Using Default Font

​Setting Base Font Size

​Loading Custom Fonts

​Basic Font Loading

​Loading Multiple Fonts

​Using Fonts

​Changing Active Font

​Dynamic Font Sizing (1.92+)

​Font Configuration

​Advanced Font Options

​Merging Fonts

​Unicode Support

​Using Unicode Text

​Loading Fonts with Specific Ranges (Pre-1.92)

​Icon Fonts

​Setup

​Using Icons

​Common Icon Font Libraries

​Loading Fonts from Memory

​From Memory Buffer

​Embedded Compressed Font

​Font Atlas

​Atlas Configuration

​Atlas Flags

​Text Rendering

​Measuring Text Size

​Colored Text

​Wrapped Text

​DPI Scaling

​Global DPI Scale (1.92+)

​Per-Platform Scaling

​Troubleshooting

​Debug Tools

​Complete Example

​Reference

Build docs developers (and LLMs) love

Fonts and Text

Quick Start

Using Default Font

Setting Base Font Size

Loading Custom Fonts

Basic Font Loading

Loading Multiple Fonts

Using Fonts

Changing Active Font

Dynamic Font Sizing (1.92+)

Font Configuration

Advanced Font Options

Merging Fonts

Unicode Support

Using Unicode Text

Loading Fonts with Specific Ranges (Pre-1.92)

Icon Fonts

Setup

Using Icons

Common Icon Font Libraries

Loading Fonts from Memory

From Memory Buffer

Embedded Compressed Font

Font Atlas

Atlas Configuration

Atlas Flags

Text Rendering

Measuring Text Size

Colored Text

Wrapped Text

DPI Scaling

Global DPI Scale (1.92+)

Per-Platform Scaling

Troubleshooting

Debug Tools

Complete Example

Reference