diff --git a/benchmarks/compare.ml b/benchmarks/compare.ml
new file mode 100644
index 0000000..2551d09
--- /dev/null
+++ b/benchmarks/compare.ml
@@ -0,0 +1,182 @@
+open Core
+
+module Both = struct
+  type 'a t =
+    { lhs : 'a
+    ; rhs : 'a
+    }
+end
+
+module Value = struct
+  type t =
+    | Int of int
+    | Float of float
+
+  let of_string s =
+    try Int (Int.of_string s) with
+    | _ -> Float (Float.of_string s)
+  ;;
+
+  let rec percent_delta x y =
+    match x, y with
+    | Int x, Int y ->
+      let delta = y - x in
+      let open Float in
+      Float (100. * Float.of_int delta / Float.of_int x)
+    | Float x, Float y -> Float Float.(100. * (y - x) / x)
+    | Float x, Int y -> percent_delta (Float x) (Float (Float.of_int y))
+    | Int x, Float y -> percent_delta (Float (Float.of_int x)) (Float y)
+  ;;
+
+  let to_csv t =
+    match t with
+    | Float f -> Float.to_string_hum f
+    | Int x -> Int.to_string_hum x
+  ;;
+
+  let compare x y =
+    match x, y with
+    | Float x, Float y -> Float.compare x y
+    | Int x, Int y -> Int.compare x y
+    | _, _ -> assert false
+  ;;
+end
+
+type 'a bench =
+  { name : string
+  ; time_per_run_nanos : 'a
+  ; major_words_per_run : 'a
+  ; promoted_words_per_run : 'a
+  ; minor_words_per_run : 'a
+  }
+
+let of_sexp (sexp : Sexp.t) =
+  match sexp with
+  | Atom _ -> failwith "expected list"
+  | List fields ->
+    let kv (sexp : Sexp.t) =
+      match sexp with
+      | List [ Atom k; Atom v ] -> Some (k, v)
+      | _ -> None
+    in
+    let fields = List.filter_map fields ~f:kv in
+    let field name =
+      List.find_map_exn fields ~f:(fun (k, v) ->
+        if String.equal k name then Some v else None)
+    in
+    let name = field "full_benchmark_name" in
+    let time_per_run_nanos = Value.of_string (field "time_per_run_nanos") in
+    let major_words_per_run = Value.of_string (field "major_words_per_run") in
+    let promoted_words_per_run = Value.of_string (field "promoted_words_per_run") in
+    let minor_words_per_run = Value.of_string (field "minor_words_per_run") in
+    { name
+    ; time_per_run_nanos
+    ; major_words_per_run
+    ; promoted_words_per_run
+    ; minor_words_per_run
+    }
+;;
+
+let parse_all s =
+  match Sexp.of_string s with
+  | Atom _ -> failwith "list expected"
+  | List benches ->
+    List.map benches ~f:of_sexp
+    |> String.Map.of_list_with_key_exn ~get_key:(fun v -> v.name)
+;;
+
+let merge_one
+  { name
+  ; time_per_run_nanos
+  ; major_words_per_run
+  ; promoted_words_per_run
+  ; minor_words_per_run
+  }
+  b
+  =
+  assert (String.equal name b.name);
+  { b with
+    time_per_run_nanos = { Both.lhs = time_per_run_nanos; rhs = b.time_per_run_nanos }
+  ; major_words_per_run = { Both.lhs = major_words_per_run; rhs = b.major_words_per_run }
+  ; promoted_words_per_run =
+      { Both.lhs = promoted_words_per_run; rhs = b.promoted_words_per_run }
+  ; minor_words_per_run = { Both.lhs = minor_words_per_run; rhs = b.minor_words_per_run }
+  }
+;;
+
+let merge lhs rhs =
+  Map.merge lhs rhs ~f:(fun ~key:_ v ->
+    match v with
+    | `Left _ -> None
+    | `Right _ -> None
+    | `Both (lhs, rhs) -> Some (merge_one lhs rhs))
+;;
+
+let run ~prev ~next =
+  let report =
+    let prev = Stdio.In_channel.read_all prev |> parse_all in
+    let next = Stdio.In_channel.read_all next |> parse_all in
+    merge prev next
+  in
+  let records =
+    let headers =
+      [ "name"
+      ; "time_per_run_nanos"
+      ; "delta (%)"
+      ; "major_words_per_run"
+      ; "delta (%)"
+      ; "promoted_words_per_run"
+      ; "delta (%)"
+      ; "minor_words_per_run"
+      ; "delta (%)"
+      ]
+    in
+    let values =
+      Map.to_alist report
+      |> List.map ~f:snd
+      |> List.map
+           ~f:
+             (fun
+               ({ name
+                ; time_per_run_nanos
+                ; major_words_per_run
+                ; promoted_words_per_run
+                ; minor_words_per_run
+                } :
+                 Value.t Both.t bench)
+             ->
+             let time_delta =
+               Value.percent_delta time_per_run_nanos.lhs time_per_run_nanos.rhs
+             in
+             let make_delta { Both.lhs; rhs } =
+               let delta = Value.percent_delta lhs rhs in
+               [ Value.to_csv lhs; Value.to_csv delta ]
+             in
+             ( time_delta
+             , name
+               :: List.concat
+                    [ make_delta time_per_run_nanos
+                    ; make_delta major_words_per_run
+                    ; make_delta promoted_words_per_run
+                    ; make_delta minor_words_per_run
+                    ] ))
+      |> List.sort ~compare:(fun (x, _) (y, _) -> Value.compare x y)
+      |> List.map ~f:snd
+    in
+    headers :: values
+  in
+  let chan = Csv.to_channel Stdio.stdout in
+  Csv.output_all chan records
+;;
+
+let command =
+  let open Command.Param in
+  let open Command.Param.Applicative_infix in
+  Command.basic
+    ~summary:"compare two runs"
+    (let prev = flag "prev" (required string) ~doc:"sexp file" in
+     let next = flag "next" (required string) ~doc:"sexp file" in
+     Command.Param.return (fun prev next () -> run ~prev ~next) <*> prev <*> next)
+;;
+
+let () = Command_unix.run command
diff --git a/benchmarks/dune b/benchmarks/dune
index 50d43fe..5af1cef 100644
--- a/benchmarks/dune
+++ b/benchmarks/dune
@@ -13,4 +13,19 @@
   core_bench
   core_unix.command_unix
   memtrace)
+ (modules :standard \ compare)
  (names benchmark))
+
+(executable
+ (name compare)
+ (modules compare)
+ (libraries
+  core
+  csv
+  base
+  core_unix
+  core_unix.command_unix
+  core_unix.filename_unix
+  spawn
+  stdio
+  sexplib))
diff --git a/flake.nix b/flake.nix
index 8e4de83..5b4d475 100644
--- a/flake.nix
+++ b/flake.nix
@@ -23,6 +23,8 @@
           with pkgs.ocamlPackages; [
             ocaml-lsp
             pkgs.ocamlformat_0_26_2
+            csv
+            pkgs.tabview
           ];
         makePackages = pkgs: rec {
           default = re;