Fonts and Text

Learn how to load custom fonts, handle Unicode text, and use icon fonts in Dear ImGui.

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

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