diff --git a/packages/page-contracts/src/Contracts/Call.tsx b/packages/page-contracts/src/Contracts/Call.tsx
index 1b7b7e66ac..20c6ad56c5 100644
--- a/packages/page-contracts/src/Contracts/Call.tsx
+++ b/packages/page-contracts/src/Contracts/Call.tsx
@@ -28,6 +28,8 @@ interface Props {
   onClose: () => void;
 }
 
+const MAX_CALL_WEIGHT = new BN(5_000_000_000_000).subn(1);
+
 function Call ({ className = '', contract, messageIndex, onCallResult, onChangeMessage, onClose }: Props): React.ReactElement<Props> | null {
   const { t } = useTranslation();
   const message = contract.abi.messages[messageIndex];
@@ -76,7 +78,7 @@ function Call ({ className = '', contract, messageIndex, onCallResult, onChangeM
       if (!accountId || !message || !value || !weight) return;
 
       contract
-        .read(message, message.isPayable ? value : 0, weight.weight, ...params)
+        .read(message, message.isPayable ? value : 0, weight.isEmpty ? -1 : weight.weight, ...params)
         .send(accountId)
         .then((result): void => {
           setOutcomes([{
@@ -159,8 +161,9 @@ function Call ({ className = '', contract, messageIndex, onCallResult, onChangeM
           />
         )}
         <InputMegaGas
-          estimatedWeight={estimatedWeight}
+          estimatedWeight={message.isMutating ? estimatedWeight : MAX_CALL_WEIGHT}
           help={t<string>('The maximum amount of gas to use for this contract call. If the call requires more, it will fail.')}
+          isCall={!message.isMutating}
           weight={weight}
         />
         {message.isMutating && (
diff --git a/packages/page-contracts/src/shared/InputMegaGas.tsx b/packages/page-contracts/src/shared/InputMegaGas.tsx
index 4f67028494..1365537e08 100644
--- a/packages/page-contracts/src/shared/InputMegaGas.tsx
+++ b/packages/page-contracts/src/shared/InputMegaGas.tsx
@@ -7,6 +7,7 @@ import BN from 'bn.js';
 import React, { useEffect, useMemo, useState } from 'react';
 import styled from 'styled-components';
 import { InputNumber, Toggle } from '@polkadot/react-components';
+import { BN_ZERO } from '@polkadot/util';
 
 import { useTranslation } from '../translate';
 
@@ -14,16 +15,19 @@ interface Props {
   className?: string;
   estimatedWeight?: BN;
   help: React.ReactNode;
+  isCall?: boolean;
   weight: UseWeight;
 }
 
-function InputMegaGas ({ className, estimatedWeight, help, weight: { executionTime, isValid, megaGas, percentage, setMegaGas } }: Props): React.ReactElement<Props> {
+const MEGA = new BN(1_000_000);
+
+function InputMegaGas ({ className, estimatedWeight, help, isCall, weight: { executionTime, isValid, megaGas, percentage, setIsEmpty, setMegaGas } }: Props): React.ReactElement<Props> {
   const { t } = useTranslation();
-  const [withEstimate, setWithEstimate] = useState(false);
+  const [withEstimate, setWithEstimate] = useState(true);
 
   const estimatedMg = useMemo(
     () => estimatedWeight
-      ? estimatedWeight.divn(1e6).iaddn(1)
+      ? estimatedWeight.div(MEGA).iaddn(1)
       : null,
     [estimatedWeight]
   );
@@ -32,6 +36,10 @@ function InputMegaGas ({ className, estimatedWeight, help, weight: { executionTi
     withEstimate && estimatedMg && setMegaGas(estimatedMg);
   }, [estimatedMg, setMegaGas, withEstimate]);
 
+  useEffect((): void => {
+    setIsEmpty(withEstimate && !!isCall);
+  }, [isCall, setIsEmpty, withEstimate]);
+
   const isDisabled = !!estimatedMg && withEstimate;
 
   return (
@@ -41,18 +49,23 @@ function InputMegaGas ({ className, estimatedWeight, help, weight: { executionTi
         help={help}
         isDisabled={isDisabled}
         isError={!isValid}
+        isZeroable={isCall}
         label={
-          estimatedMg
+          estimatedMg && (isCall ? !withEstimate : true)
             ? t<string>('max gas allowed (M, {{estimatedMg}} estimated)', { replace: { estimatedMg: estimatedMg.toString() } })
             : t<string>('max gas allowed (M)')
         }
         onChange={isDisabled ? undefined : setMegaGas}
-        value={isDisabled ? undefined : megaGas}
+        value={isDisabled ? undefined : ((isCall && withEstimate) ? BN_ZERO : megaGas)}
       >
-        {estimatedWeight && (
+        {(estimatedWeight || isCall) && (
           <Toggle
             isOverlay
-            label={t<string>('use estimated gas')}
+            label={
+              isCall
+                ? t<string>('max read gas')
+                : t<string>('use estimated gas')
+            }
             onChange={setWithEstimate}
             value={withEstimate}
           />
diff --git a/packages/page-contracts/src/types.ts b/packages/page-contracts/src/types.ts
index 43ba9d13a2..a86c91aacb 100644
--- a/packages/page-contracts/src/types.ts
+++ b/packages/page-contracts/src/types.ts
@@ -27,9 +27,11 @@ export interface ContractJsonOld {
 
 export interface UseWeight {
   executionTime: number;
+  isEmpty: boolean;
   isValid: boolean;
   megaGas: BN;
   percentage: number;
+  setIsEmpty: React.Dispatch<boolean>
   setMegaGas: React.Dispatch<BN | undefined>;
   weight: BN;
 }
diff --git a/packages/page-contracts/src/useWeight.ts b/packages/page-contracts/src/useWeight.ts
index 071fbea487..c74ba6e710 100644
--- a/packages/page-contracts/src/useWeight.ts
+++ b/packages/page-contracts/src/useWeight.ts
@@ -8,12 +8,13 @@ import { useCallback, useMemo, useState } from 'react';
 import { useApi, useBlockTime } from '@polkadot/react-hooks';
 import { BN_TEN, BN_ZERO } from '@polkadot/util';
 
-const BN_MILLION = new BN(1e6);
+const BN_MILLION = new BN(1_000_000);
 
 export default function useWeight (): UseWeight {
   const { api } = useApi();
   const [blockTime] = useBlockTime();
   const [megaGas, _setMegaGas] = useState<BN>(api.consts.system.maximumBlockWeight.div(BN_MILLION).div(BN_TEN));
+  const [isEmpty, setIsEmpty] = useState(false);
 
   const setMegaGas = useCallback(
     (value?: BN | undefined) => _setMegaGas(value || api.consts.system.maximumBlockWeight.div(BN_MILLION).div(BN_TEN)),
@@ -38,11 +39,13 @@ export default function useWeight (): UseWeight {
 
     return {
       executionTime,
-      isValid,
+      isEmpty,
+      isValid: isEmpty || isValid,
       megaGas: megaGas || BN_ZERO,
       percentage,
+      setIsEmpty,
       setMegaGas,
       weight
     };
-  }, [api, blockTime, megaGas, setMegaGas]);
+  }, [api, blockTime, isEmpty, megaGas, setIsEmpty, setMegaGas]);
 }