diff --git a/labeler/adapter/fastapi.py b/labeler/adapter/fastapi.py
new file mode 100644
index 0000000..e69de29
diff --git a/labeler/app/labeler.py b/labeler/app/labeler.py
new file mode 100644
index 0000000..a4ecc72
--- /dev/null
+++ b/labeler/app/labeler.py
@@ -0,0 +1,25 @@
+from labeler.domain.objects import Label, LabelRequest, LabelDefinition
+from labeler.interfaces import Renderer, Printer
+
+
+class Application:
+    def __init__(self, renderer: Renderer, printer: Printer):
+        self.renderer = renderer
+        self.printer = printer
+
+    def render_preview(self, label_request: LabelRequest):
+        media = self.printer.get_installed_media()
+
+        if label_request.length is not None:
+            label_length = label_request.length - 2 * media.minimal_margin_horizontal
+        else:
+            label_length = media.printable_length
+
+        label_definition = LabelDefinition(
+            text=label_request.text,
+            length=label_length,
+            width=media.printable_width,
+            dpi=media.dpi,
+        )
+
+        self.renderer.render_label(label_definition)
diff --git a/labeler/domain/objects.py b/labeler/domain/objects.py
new file mode 100644
index 0000000..950efba
--- /dev/null
+++ b/labeler/domain/objects.py
@@ -0,0 +1,123 @@
+import io
+from math import inf
+
+from pydantic import BaseModel, Field
+
+
+class Image(BaseModel):
+    bytes: bytes
+    width: int
+    height: int
+
+    @classmethod
+    def from_pil(cls, pil_image):
+        buffer = io.BytesIO()
+        pil_image.save(buffer, format="PNG")
+        buffer.seek(0)
+
+        return cls(
+            bytes=buffer.read(),
+            width=pil_image.width,
+            height=pil_image.height,
+        )
+
+
+class Dimension(BaseModel):
+    mm: float
+    __EPSILON = 0.0001
+
+    @classmethod
+    def from_inch(cls, inch: float) -> "Dimension":
+        return cls(mm=inch * 25.4)
+
+    @classmethod
+    def from_points(cls, points: float, dpi: int) -> "Dimension":
+        return cls.from_inch(points / dpi)
+
+    @property
+    def inch(self) -> float:
+        return self.mm / 25.4
+
+    def in_pixels(self, dpi: int) -> int:
+        return int(self.inch * dpi)
+
+    def __ensure_same_type(self, other):
+        if type(other) != Dimension:
+            raise TypeError(f"Cannot use {other} to {self}")
+
+    def __add__(self, other):
+        self.__ensure_same_type(other)
+        return Dimension(mm=self.mm + other.mm)
+
+    def __sub__(self, other):
+        self.__ensure_same_type(other)
+        return Dimension(mm=self.mm - other.mm)
+
+    def __mul__(self, other):
+        if type(other) not in (int, float):
+            raise TypeError(f"Cannot multiply {self} by {other}")
+        return Dimension(mm=self.mm * other)
+
+    def __rmul__(self, other):
+        return self.__mul__(other)
+
+    def __truediv__(self, other):
+        if type(other) not in (int, float):
+            raise TypeError(f"Cannot divide {self} by {other}")
+
+        return Dimension(mm=self.mm / other)
+
+    def __eq__(self, other):
+        self.__ensure_same_type(other)
+        if self.mm == inf and other.mm == inf:
+            return True
+        return abs(self.mm - other.mm) < self.__EPSILON
+
+    def __lt__(self, other):
+        self.__ensure_same_type(other)
+        return self.mm < other.mm
+
+    def __gt__(self, other):
+        self.__ensure_same_type(other)
+        return self.mm > other.mm
+
+
+class LabelRequest(BaseModel):
+    text: str
+    length: Dimension | None
+
+
+class LabelDefinition(BaseModel):
+    text: str
+    length: Dimension | None = None
+    width: Dimension
+    dpi: int
+
+    @property
+    def pixel_width(self):
+        return self.width.in_pixels(self.dpi)
+
+    @property
+    def pixel_length(self):
+        return self.length.in_pixels(self.dpi)
+
+
+class MediaDefinition(BaseModel):
+    width: Dimension
+    length: Dimension
+    minimal_margin_vertical: Dimension
+    minimal_margin_horizontal: Dimension
+    dpi: int
+
+    @property
+    def printable_width(self) -> Dimension:
+        return self.width - 2 * self.minimal_margin_horizontal
+
+    @property
+    def printable_length(self) -> Dimension:
+        return self.length - 2 * self.minimal_margin_vertical
+
+
+class Label(BaseModel):
+    dpi: str
+    image: Image
diff --git a/labeler/infra/renderer.py b/labeler/infra/renderer.py
new file mode 100644
index 0000000..59a3bcc
--- /dev/null
+++ b/labeler/infra/renderer.py
@@ -0,0 +1,125 @@
+import textwrap
+from string import ascii_letters
+
+from PIL import ImageFont, ImageDraw, Image as PILImage
+
+from labeler.domain.objects import Image, LabelDefinition
+from labeler.interfaces import Renderer
+
+
+class PILRenderer(Renderer):
+    def __init__(self):
+        self.font_path = "/Library/Fonts/Arial.ttf"
+
+    def render_label(self, label_definition: LabelDefinition) -> Image:
+        if label_definition.length is None:
+            pil_image = self.__render_no_fixed_lenth(label_definition)
+        else:
+            pil_image = self.__render_fixed_length(label_definition)
+
+        return Image.from_pil(pil_image)
+
+    def __render_fixed_length(self, label_definition: LabelDefinition):
+        width = label_definition.pixel_width
+        length = label_definition.pixel_length
+        font, text = self.__get_font(
+            label_definition.text,
+            width,
+            length,
+        )
+        im = PILImage.new("1", (length, width), 1)
+        draw = ImageDraw.Draw(im)
+        draw.text(
+            (length / 2, width / 2),
+            text,
+            font=font,
+            fill=0,
+            anchor="mm",
+            align="center",
+        )
+        return im
+
+    def __render_no_fixed_lenth(self, label_definition: LabelDefinition):
+        lines_to_print = label_definition.text.count("\n") + 1
+        text = "\n".join([line.strip() for line in label_definition.text.split("\n")])
+
+        text_height = label_definition.pixel_width // lines_to_print
+
+        while text_height > 0:
+            font = ImageFont.truetype(
+                "/Library/Fonts/Arial.ttf",
+                text_height,
+            )
+            if lines_to_print > 1:
+                occupied_height = font.getsize_multiline(text)[1]
+            else:
+                occupied_height = font.getsize(text)[1]
+            if occupied_height <= label_definition.pixel_width:
+                break
+            text_height -= 1
+
+        sizes = [font.getsize(line) for line in text.split("\n")]
+
+        length = max(length for length, height in sizes)
+
+        im = PILImage.new("1", (length, label_definition.pixel_width), 1)
+        draw = ImageDraw.Draw(im)
+        draw.text(
+            (length / 2, label_definition.pixel_width / 2),
+            text,
+            font=font,
+            fill=0,
+            anchor="mm",
+            align="center",
+        )
+        return im
+
+    def __get_font(self, text: str, max_width: int, max_length: int):
+        font_size = max_width
+        step = max_width // 2
+        last_good = None
+        last_corrected = None
+        while step > 1:
+            fits, corrected = self.__will_font_fit(
+                text, self.font_path, font_size, max_width, max_length
+            )
+            if fits:
+                last_good = font_size
+                last_corrected = corrected
+                font_size += step
+            else:
+                font_size -= step
+            step //= 2
+
+        return ImageFont.truetype(self.font_path, last_good), last_corrected
+
+    def __will_font_fit(
+        self, text: str, font_path: str, font_size: int, max_width: int, max_length: int
+    ):
+        font = ImageFont.truetype(font_path, font_size)
+        if "\n" in text:
+            text_width, text_height = font.getsize_multiline(text)
+        else:
+            text_width, text_height = font.getsize(text)
+
+        if text_height > max_width:
+            return False, None
+
+        if text_width <= max_length:
+            # Now we know that the text fits. We can stop trying
+            return True, text
+
+        avg_char_width = sum(font.getsize(char)[0] for char in ascii_letters) / len(
+            ascii_letters
+        )
+        charachters_per_line = max_length // avg_char_width
+        if charachters_per_line < max(len(line) for line in text.split(" ")):
+            return False, None
+
+        wrapped = textwrap.fill(text, charachters_per_line)
+        wrapped_width, wrapped_height = font.getsize_multiline(wrapped)
+        if wrapped_height <= max_width and wrapped_width <= max_length:
+            # Now we know that the text fits. We can stop trying
+            return True, wrapped
+
+        return False, None
diff --git a/labeler/interfaces.py b/labeler/interfaces.py
new file mode 100644
index 0000000..fdbc9d5
--- /dev/null
+++ b/labeler/interfaces.py
@@ -0,0 +1,15 @@
+import abc
+
+from labeler.domain.objects import LabelDefinition, Image, MediaDefinition
+
+
+class Renderer(abc.ABC):
+    @abc.abstractmethod
+    def render_label(self, label_definition: LabelDefinition) -> Image:
+        pass
+
+
+class Printer(abc.ABC):
+    @abc.abstractmethod
+    def get_installed_media(self) -> MediaDefinition:
+        pass
diff --git a/tests/conftest.py b/tests/conftest.py
new file mode 100644
index 0000000..84fb7c4
--- /dev/null
+++ b/tests/conftest.py
@@ -0,0 +1 @@
+from fixtures import *  # noqa
diff --git a/tests/fixtures.py b/tests/fixtures.py
new file mode 100644
index 0000000..5167dfc
--- /dev/null
+++ b/tests/fixtures.py
@@ -0,0 +1,25 @@
+import os
+from typing import Callable
+
+import pytest
+
+
+@pytest.fixture
+def current_dir(request) -> str:
+    return os.path.dirname(request.module.__file__)
+
+
+@pytest.fixture
+def get_test_image(current_dir) -> Callable[[str], bytes]:
+    def f(name):
+        return open(os.path.join(current_dir, "test_images", name), "rb").read()
+
+    return f
+
+
+@pytest.fixture
+def save_test_image(current_dir) -> Callable[[str, bytes], None]:
+    def f(name: str, data: bytes):
+        open(os.path.join(current_dir, "test_images", name), "wb").write(data)
+
+    return f
diff --git a/tests/labeler/domain/test_objects.py b/tests/labeler/domain/test_objects.py
new file mode 100644
index 0000000..fc20f24
--- /dev/null
+++ b/tests/labeler/domain/test_objects.py
@@ -0,0 +1,29 @@
+import math
+
+from labeler.domain.objects import Dimension, MediaDefinition
+
+
+def test_dimension():
+    dimension = Dimension(mm=25.4)
+
+    assert dimension.mm == 25.4
+    assert dimension.inch == 1.0
+
+    assert dimension.in_pixels(dpi=300) == 300
+
+    assert dimension + Dimension(mm=10) == Dimension(mm=35.4)
+    assert dimension * 2 == Dimension(mm=50.8)
+
+    assert dimension / 2 == Dimension(mm=12.7)
+
+
+def test_infinite_media():
+    media = MediaDefinition(
+        width=Dimension(mm=12),
+        length=Dimension(mm=math.inf),
+        minimal_margin_vertical=Dimension(mm=1),
+        minimal_margin_horizontal=Dimension(mm=2),
+        dpi=300,
+    )
+
+    assert media.printable_length == Dimension(mm=math.inf)
diff --git a/tests/labeler/infra/test_images/multiline_label_no_fixed_width.png b/tests/labeler/infra/test_images/multiline_label_no_fixed_width.png
new file mode 100644
index 0000000..60a35ed
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diff --git a/tests/labeler/infra/test_images/multiline_label_test.png b/tests/labeler/infra/test_images/multiline_label_test.png
new file mode 100644
index 0000000..d7a81e2
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diff --git a/tests/labeler/infra/test_images/no_fixed_width.png b/tests/labeler/infra/test_images/no_fixed_width.png
new file mode 100644
index 0000000..abec891
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diff --git a/tests/labeler/infra/test_images/simple_label_test.png b/tests/labeler/infra/test_images/simple_label_test.png
new file mode 100644
index 0000000..46caf96
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diff --git a/tests/labeler/infra/test_renderer.py b/tests/labeler/infra/test_renderer.py
new file mode 100644
index 0000000..f3597bc
--- /dev/null
+++ b/tests/labeler/infra/test_renderer.py
@@ -0,0 +1,50 @@
+from labeler.domain.objects import LabelDefinition, Dimension
+from labeler.infra.renderer import PILRenderer
+
+
+def test_simple_label(get_test_image):
+    renderer = PILRenderer()
+    expected_label = get_test_image("simple_label_test.png")
+
+    definition = LabelDefinition(
+        text="dolphin", length=Dimension(mm=40), width=Dimension(mm=10), dpi=600
+    )
+
+    label = renderer.render_label(definition)
+
+    assert label.bytes == expected_label
+
+
+def test_multiline_label(get_test_image):
+    label_text = "dolphin\nis\nawesome"
+    expected_label = get_test_image("multiline_label_test.png")
+
+    renderer = PILRenderer()
+    definition = LabelDefinition(
+        text=label_text, length=Dimension(mm=40), width=Dimension(mm=10), dpi=600
+    )
+
+    label = renderer.render_label(definition)
+    assert label.bytes == expected_label
+
+
+def test_simple_label_no_fixed_width(get_test_image, save_test_image):
+    renderer = PILRenderer()
+    expected_label = get_test_image("no_fixed_width.png")
+
+    definition = LabelDefinition(text="dolphin", width=Dimension(mm=10), dpi=600)
+
+    label = renderer.render_label(definition)
+    assert label.bytes == expected_label
+
+
+def test_multiline_label_no_fixed_width(get_test_image, save_test_image):
+    renderer = PILRenderer()
+    expected_label = get_test_image("multiline_no_fixed_width.png")
+
+    definition = LabelDefinition(
+        text="dolphin\nis\nawesome", width=Dimension(mm=10), dpi=600
+    )
+
+    label = renderer.render_label(definition)
+    assert label.bytes == expected_label