# Canvas size limits

> The HTML canvas max size depends on the browser, and iOS Safari is the smallest. Check pages, exports and images before any canvas is made.

Source: https://fabricjs-document-engine.jscrate.dev/docs/guides/canvas-size-limits
Last updated: 2026-10-02

Every browser has an HTML canvas max size, and above it the canvas stays blank or the tab runs out of memory. The limit is not the same everywhere: desktop Chrome allows a side of 32,767 pixels, while iOS Safari allows about 67 million pixels in total, a square of 8,192. A design that exports fine on a laptop can then fail on an iPhone, often without an error.

## Try it

```tsx
"use client";

import { isDocumentEngineError } from "fabricjs-document-engine";
import { useDocumentEngine } from "fabricjs-document-engine/react";
import { ExpandIcon, ImageIcon, MaximizeIcon } from "lucide-react";
import { useTranslations } from "next-intl";
import { useEffect, useState } from "react";

import {
  DemoCanvas,
  DemoFrame,
  seedShapes,
  Status,
  Toolbar,
  ToolButton,
} from "./demo-ui";
import { useFabricCanvas } from "./use-fabric-canvas";

export default function SizeLimitsDemo() {
  const t = useTranslations("demos");
  const { elementRef, canvas } = useFabricCanvas();
  const engine = useDocumentEngine(canvas);
  const [message, setMessage] = useState<{
    tone: "ok" | "error";
    text: string;
  } | null>(null);

  useEffect(() => {
    if (!engine) return;
    engine.canvas.add(...seedShapes());
    engine.clearHistory();
  }, [engine]);

  async function check(scale: number) {
    if (!engine) return;
    const preflight = await engine.preflightExport({ format: "png", scale });
    const problem = preflight.problems[0];
    setMessage(
      problem
        ? {
            tone: "error",
            text: t("sizeLimits.refused", { code: problem.code, scale }),
          }
        : {
            tone: "ok",
            text: t("sizeLimits.fine", {
              scale,
              width: 480 * scale,
              height: 300 * scale,
            }),
          }
    );
  }

  function hugePage() {
    if (!engine) return;
    try {
      engine.setPage({ width: 20000, height: 20000 });
    } catch (error) {
      setMessage({
        tone: "error",
        text: t("sizeLimits.page", {
          code: isDocumentEngineError(error) ? error.code : String(error),
        }),
      });
    }
  }

  return (
    <DemoFrame>
      <DemoCanvas elementRef={elementRef} label={t("canvas")} />

      <Toolbar>
        <ToolButton
          icon={ImageIcon}
          label={t("sizeLimits.small")}
          disabled={!engine}
          onClick={() => void check(4)}
        />
        <ToolButton
          icon={MaximizeIcon}
          label={t("sizeLimits.large")}
          primary
          disabled={!engine}
          onClick={() => void check(60)}
        />
        <ToolButton
          icon={ExpandIcon}
          label={t("sizeLimits.hugePage")}
          disabled={!engine}
          onClick={hugePage}
        />
      </Toolbar>

      <Status tone={message?.tone ?? "idle"}>
        {message?.text ?? t("sizeLimits.hint")}
      </Status>
    </DemoFrame>
  );
}
```

```tsx
import { Canvas } from "fabric";
import { useLayoutEffect, useRef, useState } from "react";

/**
 * The page every demo draws on. The document keeps this size; CSS scales the
 * canvas down to fit its card, so saved documents and exports never depend on
 * the screen.
 */
export const PAGE = { width: 480, height: 300 };

// Selection handles in the site's style. Fabric does not save these.
const SELECTION = {
  borderColor: "#6f00ff",
  borderScaleFactor: 1.5,
  borderOpacityWhenMoving: 0.5,
  cornerStyle: "circle",
  cornerSize: 11,
  cornerColor: "#ffffff",
  cornerStrokeColor: "#6f00ff",
  transparentCorners: false,
} as const;

export function styleSelection(canvas: Canvas) {
  canvas.set({
    selectionColor: "rgba(111, 0, 255, 0.06)",
    selectionBorderColor: "#6f00ff",
    selectionLineWidth: 1,
  });
  const style = () => canvas.getActiveObject()?.set(SELECTION);
  canvas.on("selection:created", style);
  canvas.on("selection:updated", style);
}

/**
 * Creates a Fabric.js canvas once the `<canvas>` element exists, and disposes
 * it on unmount. The engine is created from the returned `canvas`.
 */
export function useFabricCanvas({ width, height } = PAGE) {
  const elementRef = useRef<HTMLCanvasElement>(null);
  const [canvas, setCanvas] = useState<Canvas | null>(null);

  // A layout effect creates the canvas before the first paint.
  useLayoutEffect(() => {
    const created = new Canvas(elementRef.current!, {
      width,
      height,
      backgroundColor: "#ffffff",
    });
    styleSelection(created);
    setCanvas(created);

    return () => {
      // Dispose after the engine's own cleanup, so its last recovery copy
      // still sees the objects.
      setTimeout(() => created.dispose().catch(() => undefined));
    };
  }, [width, height]);

  return { elementRef, canvas };
}
```

```tsx
import { Circle, type FabricObject, Rect, Triangle } from "fabric";
import type { LucideIcon } from "lucide-react";

import { cn } from "@/lib/utils";

import { PAGE } from "./use-fabric-canvas";

export const COLORS = ["#f2836f", "#5fe6c4", "#7ad9ec", "#6f00ff", "#ffd666"];

// Demo shapes are placed by their top-left corner, like a design tool.
const CORNER = { originX: "left", originY: "top" } as const;

/** A new shape at a random spot on the page. */
export function newShape(kind: "square" | "circle", fill?: string) {
  const left = 40 + Math.random() * (PAGE.width - 160);
  const top = 30 + Math.random() * (PAGE.height - 120);
  const color = fill ?? COLORS[Math.floor(Math.random() * COLORS.length)];
  return kind === "square"
    ? new Rect({
        ...CORNER,
        left,
        top,
        width: 88,
        height: 64,
        rx: 10,
        ry: 10,
        fill: color,
      })
    : new Circle({ ...CORNER, left, top, radius: 34, fill: color });
}

/** A small composed drawing, so no demo starts on an empty page. */
export function seedShapes(): FabricObject[] {
  return [
    new Rect({
      ...CORNER,
      left: 48,
      top: 56,
      width: 176,
      height: 124,
      rx: 16,
      ry: 16,
      fill: COLORS[4],
    }),
    new Circle({ ...CORNER, left: 268, top: 44, radius: 58, fill: COLORS[0] }),
    new Rect({
      ...CORNER,
      left: 256,
      top: 196,
      width: 176,
      height: 52,
      rx: 26,
      ry: 26,
      fill: COLORS[1],
    }),
    new Triangle({
      ...CORNER,
      left: 96,
      top: 196,
      width: 72,
      height: 60,
      fill: COLORS[3],
    }),
  ];
}

export function DemoFrame({
  className,
  ...props
}: React.ComponentProps<"div">) {
  return (
    <div
      className={cn(
        "flex w-full max-w-md flex-col gap-3 text-left outline-none",
        className
      )}
      {...props}
    />
  );
}

/**
 * Scales the fixed-size Fabric canvas to the frame's width. The rules are
 * `!important` because Fabric writes its sizes as inline styles.
 */
export function DemoCanvas({
  elementRef,
  label,
  page = PAGE,
  children,
}: {
  elementRef: React.Ref<HTMLCanvasElement>;
  label: string;
  page?: { width: number; height: number };
  children?: React.ReactNode;
}) {
  return (
    <div
      className="relative overflow-hidden rounded-lg border bg-white shadow-xs [&_.canvas-container]:aspect-(--page)! [&_.canvas-container]:h-auto! [&_.canvas-container]:w-full! [&_canvas]:h-full! [&_canvas]:w-full!"
      style={
        { "--page": `${page.width} / ${page.height}` } as React.CSSProperties
      }
    >
      <div>
        <canvas ref={elementRef} aria-label={label} />
      </div>
      {children}
    </div>
  );
}

export function Toolbar({ className, ...props }: React.ComponentProps<"div">) {
  return (
    <div
      className={cn("flex flex-wrap items-center gap-1.5", className)}
      {...props}
    />
  );
}

export function ToolButton({
  icon: Icon,
  label,
  iconOnly = false,
  primary = false,
  className,
  ...props
}: React.ComponentProps<"button"> & {
  icon: LucideIcon;
  label: string;
  iconOnly?: boolean;
  primary?: boolean;
}) {
  return (
    <button
      type="button"
      title={label}
      aria-label={iconOnly ? label : undefined}
      className={cn(
        "inline-flex h-8 min-w-0 items-center justify-center gap-1.5 rounded-md border px-2.5 text-[13px] font-medium whitespace-nowrap transition-colors disabled:pointer-events-none disabled:opacity-40 [&_svg]:size-3.5 [&_svg]:shrink-0",
        primary
          ? "border-transparent bg-foreground text-background hover:bg-foreground/85"
          : "bg-background hover:bg-muted",
        iconOnly && "w-8 px-0",
        className
      )}
      {...props}
    >
      <Icon aria-hidden />
      {!iconOnly && <span className="truncate">{label}</span>}
    </button>
  );
}

const TONES = {
  idle: "bg-zinc-400",
  busy: "bg-amber-400",
  ok: "bg-emerald-500",
  error: "bg-red-500",
};

/** One line of status text. Its height never changes, so the card never jumps. */
export function Status({
  tone = "idle",
  children,
}: {
  tone?: keyof typeof TONES;
  children: React.ReactNode;
}) {
  return (
    <p
      role="status"
      className="flex h-5 min-w-0 items-center gap-2 text-[13px] text-muted-foreground"
    >
      <span
        aria-hidden
        className={cn("size-1.5 shrink-0 rounded-full", TONES[tone])}
      />
      <span className="truncate">{children}</span>
    </p>
  );
}
```

The 4× export fits. The 60× export would be 28,800 pixels wide and is refused before any canvas is made, and so is a page of 20,000 × 20,000.

## The limits

```ts
const engine = createDocumentEngine({
  canvas,
  limits: {
    maxCanvasSide: 16384,
    maxCanvasPixels: 8192 * 8192,
    maxImagePixels: 8192 * 8192,
    maxDocumentLength: 100_000_000,
  },
});
```

| Limit               | Default             | Checked on                                    |
| ------------------- | ------------------- | --------------------------------------------- |
| `maxCanvasSide`     | 16,384              | The page, and PNG, JPEG, WebP and PDF exports |
| `maxCanvasPixels`   | 67,108,864 (8,192²) | The page and raster exports                   |
| `maxImagePixels`    | 67,108,864          | Each image, after it is decoded               |
| `maxDocumentLength` | 100,000,000         | The JSON of a document that is loaded         |

The defaults match the strictest common browser, iOS Safari. Raise them only for an editor that runs on desktop browsers. Each check is a multiplication done before any canvas exists, so it costs nothing.

## Exports

```ts
const preflight = await engine.preflightExport({ format: "png", scale: 4 });

if (!preflight.ok) {
  const tooLarge = preflight.problems.find(
    (problem) => problem.code === "TOO_LARGE"
  );
  if (tooLarge) showMessage(tooLarge.message);
}
```

An export over the canvas size limit fails with `EXPORT_BLOCKED` and a `TOO_LARGE` problem, which says the size it would have had. PDF export instead draws the page at a lower resolution, so a PDF still comes out.

## Resize the canvas

Use `setPage` to resize the canvas or change its background. The change is one undo step, and a size above the limits is refused with `UNSAFE_DOCUMENT` before anything changes:

```ts
try {
  engine.setPage({ width: 3000, height: 2000, background: "#ffffff" });
} catch (error) {
  if (isDocumentEngineError(error)) showMessage(error.message);
}
```

## Images and documents

An image above `maxImagePixels` fails to load with the reason `TOO_LARGE`, and a document whose page or JSON is over the limits is refused with `UNSAFE_DOCUMENT`. Both are checked before Fabric decodes or creates anything. The [error codes](https://fabricjs-document-engine.jscrate.dev/docs/api/error-codes) list every code, and the [security](https://fabricjs-document-engine.jscrate.dev/docs/guides/security) page covers the other limits. Stay under the HTML canvas max size and every device can open and export the document.