diff --git a/packages/sdk/package.json b/packages/sdk/package.json
index ff5ec0125d..81fc4ce588 100644
--- a/packages/sdk/package.json
+++ b/packages/sdk/package.json
@@ -41,8 +41,10 @@
     "@iov/crypto": "^2.0.2",
     "@iov/encoding": "^2.0.2",
     "@iov/utils": "^2.0.2",
+    "@types/pako": "^1.0.1",
     "axios": "^0.19.0",
-    "bn.js": "^5.1.1"
+    "bn.js": "^5.1.1",
+    "pako": "^1.0.11"
   },
   "devDependencies": {
     "@types/bn.js": "^4.11.6",
diff --git a/packages/sdk/src/cosmwasmclient.spec.ts b/packages/sdk/src/cosmwasmclient.spec.ts
index d362eed9ce..0f68f2642c 100644
--- a/packages/sdk/src/cosmwasmclient.spec.ts
+++ b/packages/sdk/src/cosmwasmclient.spec.ts
@@ -321,7 +321,7 @@ describe("CosmWasmClient", () => {
         pendingWithoutWasmd();
         const pen = await Secp256k1Pen.fromMnemonic(faucet.mnemonic);
         const client = new SigningCosmWasmClient(httpUrl, faucet.address, signBytes => pen.sign(signBytes));
-        const codeId = await client.upload(getRandomizedHackatom());
+        const { codeId } = await client.upload(getRandomizedHackatom());
         const initMsg = { verifier: makeRandomAddress(), beneficiary: makeRandomAddress() };
         const contractAddress = await client.instantiate(codeId, initMsg);
         contract = { initMsg: initMsg, address: contractAddress };
@@ -372,7 +372,7 @@ describe("CosmWasmClient", () => {
         pendingWithoutWasmd();
         const pen = await Secp256k1Pen.fromMnemonic(faucet.mnemonic);
         const client = new SigningCosmWasmClient(httpUrl, faucet.address, signBytes => pen.sign(signBytes));
-        const codeId = await client.upload(getRandomizedHackatom());
+        const { codeId } = await client.upload(getRandomizedHackatom());
         const initMsg = { verifier: makeRandomAddress(), beneficiary: makeRandomAddress() };
         const contractAddress = await client.instantiate(codeId, initMsg);
         contract = { initMsg: initMsg, address: contractAddress };
diff --git a/packages/sdk/src/index.ts b/packages/sdk/src/index.ts
index ca7ceb27e4..be21fbe57b 100644
--- a/packages/sdk/src/index.ts
+++ b/packages/sdk/src/index.ts
@@ -28,4 +28,9 @@ export {
   decodeSignature,
   makeSecp256k1SignatureFromFixedLength,
 } from "./signature";
-export { SigningCallback, SigningCosmWasmClient, ExecuteResult } from "./signingcosmwasmclient";
+export {
+  SigningCallback,
+  SigningCosmWasmClient,
+  ExecuteResult,
+  UploadReceipt,
+} from "./signingcosmwasmclient";
diff --git a/packages/sdk/src/signingcosmwasmclient.spec.ts b/packages/sdk/src/signingcosmwasmclient.spec.ts
index 295e7c6ec6..70da832d9f 100644
--- a/packages/sdk/src/signingcosmwasmclient.spec.ts
+++ b/packages/sdk/src/signingcosmwasmclient.spec.ts
@@ -1,3 +1,5 @@
+import { Sha256 } from "@iov/crypto";
+import { Encoding } from "@iov/encoding";
 import { assert } from "@iov/utils";
 
 import { Secp256k1Pen } from "./pen";
@@ -6,6 +8,8 @@ import { SigningCosmWasmClient } from "./signingcosmwasmclient";
 import { getRandomizedHackatom, makeRandomAddress, pendingWithoutWasmd } from "./testutils.spec";
 import { Coin } from "./types";
 
+const { toHex } = Encoding;
+
 const httpUrl = "http://localhost:1317";
 
 const faucet = {
@@ -32,7 +36,18 @@ describe("SigningCosmWasmClient", () => {
       pendingWithoutWasmd();
       const pen = await Secp256k1Pen.fromMnemonic(faucet.mnemonic);
       const client = new SigningCosmWasmClient(httpUrl, faucet.address, signBytes => pen.sign(signBytes));
-      const codeId = await client.upload(getRandomizedHackatom());
+      const wasm = getRandomizedHackatom();
+      const {
+        codeId,
+        originalChecksum,
+        originalSize,
+        compressedChecksum,
+        compressedSize,
+      } = await client.upload(wasm);
+      expect(originalChecksum).toEqual(toHex(new Sha256(wasm).digest()));
+      expect(originalSize).toEqual(wasm.length);
+      expect(compressedChecksum).toMatch(/^[0-9a-f]{64}$/);
+      expect(compressedSize).toBeLessThan(wasm.length * 0.5);
       expect(codeId).toBeGreaterThanOrEqual(1);
     });
   });
@@ -42,7 +57,7 @@ describe("SigningCosmWasmClient", () => {
       pendingWithoutWasmd();
       const pen = await Secp256k1Pen.fromMnemonic(faucet.mnemonic);
       const client = new SigningCosmWasmClient(httpUrl, faucet.address, signBytes => pen.sign(signBytes));
-      const codeId = await client.upload(getRandomizedHackatom());
+      const { codeId } = await client.upload(getRandomizedHackatom());
 
       const transferAmount: readonly Coin[] = [
         {
@@ -74,7 +89,7 @@ describe("SigningCosmWasmClient", () => {
       pendingWithoutWasmd();
       const pen = await Secp256k1Pen.fromMnemonic(faucet.mnemonic);
       const client = new SigningCosmWasmClient(httpUrl, faucet.address, signBytes => pen.sign(signBytes));
-      const codeId = await client.upload(getRandomizedHackatom());
+      const { codeId } = await client.upload(getRandomizedHackatom());
 
       const contractAddress1 = await client.instantiate(codeId, {
         verifier: faucet.address,
@@ -93,7 +108,7 @@ describe("SigningCosmWasmClient", () => {
       pendingWithoutWasmd();
       const pen = await Secp256k1Pen.fromMnemonic(faucet.mnemonic);
       const client = new SigningCosmWasmClient(httpUrl, faucet.address, signBytes => pen.sign(signBytes));
-      const codeId = await client.upload(getRandomizedHackatom());
+      const { codeId } = await client.upload(getRandomizedHackatom());
 
       // instantiate
       const transferAmount: readonly Coin[] = [
diff --git a/packages/sdk/src/signingcosmwasmclient.ts b/packages/sdk/src/signingcosmwasmclient.ts
index 3e2c888a73..c8a6999e59 100644
--- a/packages/sdk/src/signingcosmwasmclient.ts
+++ b/packages/sdk/src/signingcosmwasmclient.ts
@@ -1,4 +1,6 @@
+import { Sha256 } from "@iov/crypto";
 import { Encoding } from "@iov/encoding";
+import pako from "pako";
 
 import { CosmWasmClient, GetNonceResult, PostTxResult } from "./cosmwasmclient";
 import { makeSignBytes, marshalTx } from "./encoding";
@@ -49,6 +51,19 @@ const defaultFees: FeeTable = {
   },
 };
 
+export interface UploadReceipt {
+  /** Size of the original wasm code in bytes */
+  readonly originalSize: number;
+  /** A hex encoded sha256 checksum of the original wasm code (that is stored on chain) */
+  readonly originalChecksum: string;
+  /** Size of the compressed wasm code in bytes */
+  readonly compressedSize: number;
+  /** A hex encoded sha256 checksum of the compressed wasm code (that stored in the transaction) */
+  readonly compressedChecksum: string;
+  /** The ID of the code asigned by the chain */
+  readonly codeId: number;
+}
+
 export interface ExecuteResult {
   readonly logs: readonly Log[];
 }
@@ -80,14 +95,15 @@ export class SigningCosmWasmClient extends CosmWasmClient {
     return super.getAccount(address || this.senderAddress);
   }
 
-  /** Uploads code and returns a code ID */
-  public async upload(wasmCode: Uint8Array, memo = ""): Promise<number> {
+  /** Uploads code and returns a receipt, including the code ID */
+  public async upload(wasmCode: Uint8Array, memo = ""): Promise<UploadReceipt> {
+    const compressed = pako.gzip(wasmCode, { level: 9 });
     const storeCodeMsg: MsgStoreCode = {
       type: "wasm/store-code",
       value: {
         sender: this.senderAddress,
         // eslint-disable-next-line @typescript-eslint/camelcase
-        wasm_byte_code: Encoding.toBase64(wasmCode),
+        wasm_byte_code: Encoding.toBase64(compressed),
         source: "",
         builder: "",
       },
@@ -106,8 +122,13 @@ export class SigningCosmWasmClient extends CosmWasmClient {
 
     const result = await this.postTx(marshalTx(signedTx));
     const codeIdAttr = findAttribute(result.logs, "message", "code_id");
-    const codeId = Number.parseInt(codeIdAttr.value, 10);
-    return codeId;
+    return {
+      originalSize: wasmCode.length,
+      originalChecksum: Encoding.toHex(new Sha256(wasmCode).digest()),
+      compressedSize: compressed.length,
+      compressedChecksum: Encoding.toHex(new Sha256(compressed).digest()),
+      codeId: Number.parseInt(codeIdAttr.value, 10),
+    };
   }
 
   public async instantiate(
diff --git a/packages/sdk/types/index.d.ts b/packages/sdk/types/index.d.ts
index dd2ad348f7..8ee2e6f914 100644
--- a/packages/sdk/types/index.d.ts
+++ b/packages/sdk/types/index.d.ts
@@ -27,4 +27,9 @@ export {
   decodeSignature,
   makeSecp256k1SignatureFromFixedLength,
 } from "./signature";
-export { SigningCallback, SigningCosmWasmClient, ExecuteResult } from "./signingcosmwasmclient";
+export {
+  SigningCallback,
+  SigningCosmWasmClient,
+  ExecuteResult,
+  UploadReceipt,
+} from "./signingcosmwasmclient";
diff --git a/packages/sdk/types/signingcosmwasmclient.d.ts b/packages/sdk/types/signingcosmwasmclient.d.ts
index 70a20ee674..4e9c352876 100644
--- a/packages/sdk/types/signingcosmwasmclient.d.ts
+++ b/packages/sdk/types/signingcosmwasmclient.d.ts
@@ -11,6 +11,18 @@ export interface FeeTable {
   readonly exec: StdFee;
   readonly send: StdFee;
 }
+export interface UploadReceipt {
+  /** Size of the original wasm code in bytes */
+  readonly originalSize: number;
+  /** A hex encoded sha256 checksum of the original wasm code (that is stored on chain) */
+  readonly originalChecksum: string;
+  /** Size of the compressed wasm code in bytes */
+  readonly compressedSize: number;
+  /** A hex encoded sha256 checksum of the compressed wasm code (that stored in the transaction) */
+  readonly compressedChecksum: string;
+  /** The ID of the code asigned by the chain */
+  readonly codeId: number;
+}
 export interface ExecuteResult {
   readonly logs: readonly Log[];
 }
@@ -27,8 +39,8 @@ export declare class SigningCosmWasmClient extends CosmWasmClient {
   );
   getNonce(address?: string): Promise<GetNonceResult>;
   getAccount(address?: string): Promise<CosmosSdkAccount | undefined>;
-  /** Uploads code and returns a code ID */
-  upload(wasmCode: Uint8Array, memo?: string): Promise<number>;
+  /** Uploads code and returns a receipt, including the code ID */
+  upload(wasmCode: Uint8Array, memo?: string): Promise<UploadReceipt>;
   instantiate(
     codeId: number,
     initMsg: object,
diff --git a/scripts/wasmd/deploy_erc20.js b/scripts/wasmd/deploy_erc20.js
index 4a13cbef16..770f6e2ca8 100755
--- a/scripts/wasmd/deploy_erc20.js
+++ b/scripts/wasmd/deploy_erc20.js
@@ -72,12 +72,12 @@ async function main() {
   const client = new SigningCosmWasmClient(httpUrl, faucet.address, signBytes => pen.sign(signBytes));
 
   const wasm = fs.readFileSync(__dirname + "/contracts/cw-erc20.wasm");
-  const codeId = await client.upload(wasm, "Upload ERC20 contract");
-  console.info(`Upload succeeded. Code ID is ${codeId}`);
+  const uploadReceipt = await client.upload(wasm, "Upload ERC20 contract");
+  console.info(`Upload succeeded. Receipt: ${JSON.stringify(uploadReceipt)}`);
 
   for (const initMsg of [initMsgHash, initMsgIsa, initMsgJade]) {
     const memo = `Create an ERC20 instance for ${initMsg.symbol}`;
-    const contractAddress = await client.instantiate(codeId, initMsg, memo);
+    const contractAddress = await client.instantiate(uploadReceipt.codeId, initMsg, memo);
     console.info(`Contract instantiated for ${initMsg.symbol} at ${contractAddress}`);
   }
 }
diff --git a/yarn.lock b/yarn.lock
index 3c1000d69b..39e36fe2ea 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -1125,6 +1125,11 @@
   resolved "https://registry.yarnpkg.com/@types/node/-/node-10.17.13.tgz#ccebcdb990bd6139cd16e84c39dc2fb1023ca90c"
   integrity sha512-pMCcqU2zT4TjqYFrWtYHKal7Sl30Ims6ulZ4UFXxI4xbtQqK/qqKwkDoBFCfooRqqmRu9vY3xaJRwxSh673aYg==
 
+"@types/pako@^1.0.1":
+  version "1.0.1"
+  resolved "https://registry.yarnpkg.com/@types/pako/-/pako-1.0.1.tgz#33b237f3c9aff44d0f82fe63acffa4a365ef4a61"
+  integrity sha512-GdZbRSJ3Cv5fiwT6I0SQ3ckeN2PWNqxd26W9Z2fCK1tGrrasGy4puvNFtnddqH9UJFMQYXxEuuB7B8UK+LLwSg==
+
 "@types/random-js@^1.0.31":
   version "1.0.31"
   resolved "https://registry.yarnpkg.com/@types/random-js/-/random-js-1.0.31.tgz#18a8bcc075afa504421e638fcbe021f27e802941"
@@ -5964,6 +5969,11 @@ p-waterfall@^1.0.0:
   dependencies:
     p-reduce "^1.0.0"
 
+pako@^1.0.11:
+  version "1.0.11"
+  resolved "https://registry.yarnpkg.com/pako/-/pako-1.0.11.tgz#6c9599d340d54dfd3946380252a35705a6b992bf"
+  integrity sha512-4hLB8Py4zZce5s4yd9XzopqwVv/yGNhV1Bl8NTmCq1763HeK2+EwVTv+leGeL13Dnh2wfbqowVPXCIO0z4taYw==
+
 pako@~1.0.5:
   version "1.0.10"
   resolved "https://registry.yarnpkg.com/pako/-/pako-1.0.10.tgz#4328badb5086a426aa90f541977d4955da5c9732"