diff --git a/Cargo.lock b/Cargo.lock
index 25efaed..5e703a8 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -653,6 +653,7 @@ dependencies = [
  "anyhow",
  "clap 4.1.1",
  "git-repository",
+ "terminal_size",
  "textplots",
 ]
 
@@ -1565,6 +1566,16 @@ dependencies = [
  "winapi-util",
 ]
 
+[[package]]
+name = "terminal_size"
+version = "0.2.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cb20089a8ba2b69debd491f8d2d023761cbf196e999218c591fa1e7e15a21907"
+dependencies = [
+ "rustix",
+ "windows-sys",
+]
+
 [[package]]
 name = "textplots"
 version = "0.8.0"
diff --git a/Cargo.toml b/Cargo.toml
index d7348ea..7bef042 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -7,4 +7,5 @@ edition = "2021"
 anyhow = "1.0.68"
 clap = { version = "4.1.1", features = ["derive", "deprecated"] }
 git-repository = "0.33.0"
+terminal_size = "0.2.3"
 textplots = "0.8.0"
diff --git a/src/main.rs b/src/main.rs
index 1fdd769..385dc3a 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -2,6 +2,7 @@ use std::path::PathBuf;
 
 use clap::Parser;
 use git_repository::{objs::tree::EntryMode, traverse::tree::Recorder, Commit, Repository};
+use terminal_size::{Height, Width};
 use textplots::{Chart, Plot, Shape};
 
 #[derive(Debug, Parser)]
@@ -9,10 +10,10 @@ struct Args {
     /// Path to a git repository.
     #[arg(default_value = ".")]
     repo: PathBuf,
-    #[arg(long, short, default_value_t = 300)]
-    width: u32,
-    #[arg(long, short, default_value_t = 150)]
-    height: u32,
+    #[arg(long)]
+    width: Option<u32>,
+    #[arg(long)]
+    height: Option<u32>,
 }
 
 fn count_lines(repo: &Repository, commit: &Commit) -> anyhow::Result<usize> {
@@ -32,6 +33,11 @@ fn count_lines(repo: &Repository, commit: &Commit) -> anyhow::Result<usize> {
 
 fn main() -> anyhow::Result<()> {
     let args = Args::parse();
+    let (Width(width), Height(height)) =
+        terminal_size::terminal_size().unwrap_or((Width(80), Height(24)));
+    let width = args.width.unwrap_or(width as u32 - 12) * 2;
+    let height = args.height.unwrap_or(height as u32 - 6) * 4;
+
     let mut repo = git_repository::discover(args.repo)?;
     repo.object_cache_size(Some(100 * 1024 * 1024));
     let commit = repo.head_commit()?;
@@ -53,14 +59,7 @@ fn main() -> anyhow::Result<()> {
         .map(|(i, l)| (i as f32, l as f32))
         .collect::<Vec<_>>();
 
-    let mut chart = Chart::new_with_y_range(
-        args.width,
-        args.height,
-        0_f32,
-        xmax as f32,
-        0_f32,
-        ymax as f32,
-    );
+    let mut chart = Chart::new_with_y_range(width, height, 0_f32, xmax as f32, 0_f32, ymax as f32);
     chart.lineplot(&Shape::Lines(&lines)).nice();
 
     Ok(())