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eth_estimateGas

Estimates the amount of gas required to execute a transaction on Avalanche C-Chain.

When to Use This Method​

eth_estimateGas is essential for:

  • Transaction Cost Calculation - Calculate total transaction costs before sending
  • Gas Optimization - Optimize gas limits to prevent overpaying
  • Smart Contract Testing - Verify contract functions will execute successfully
  • User Experience - Show users estimated fees before transaction confirmation

Parameters​

Transaction Object with the following fields:

  • from - (optional) Address sending the transaction
  • to - Address receiving the transaction
  • value - (optional) Value to transfer in wei
  • data - (optional) Contract method call data
  • gas - (optional) Gas limit (for estimation boundary)
  • gasPrice - (optional) Gas price in wei
  • maxFeePerGas - (optional) Maximum fee per gas (EIP-1559)
  • maxPriorityFeePerGas - (optional) Maximum priority fee (EIP-1559)
{
  "jsonrpc": "2.0",
  "method": "eth_estimateGas",
  "params": [{
    "from": "0xaff3454fce5edbc8cca8697c15331677e6ebcccc",
    "to": "0xfff7ac99c8e4feb60c9750054bdc14a3b2f0fb8",
    "value": "0xde0b6b3a7640000",
    "data": "0xa9059cbb000000000000000000000000fff7ac99c8e4feb60c9750054bdc14a3b2f0fb8000000000000000000000000000000000000000000000000000000000000000a"
  }],
  "id": 1
}

Returns​

QUANTITY - Estimated gas amount in hex format.

Implementation Examples​

curl -X POST https://api-avalanche-mainnet-archive.n.dwellir.com/YOUR_API_KEY/ext/bc/C/rpc \
  -H "Content-Type: application/json" \
  -d '{
    "jsonrpc": "2.0",
    "method": "eth_estimateGas",
    "params": [{
      "from": "0xaff3454fce5edbc8cca8697c15331677e6ebcccc",
      "to": "0xfff7ac99c8e4feb60c9750054bdc14a3b2f0fb8",
      "value": "0xde0b6b3a7640000"
    }],
    "id": 1
  }'

Response Example​

Successful Response​

{
  "jsonrpc": "2.0",
  "id": 1,
  "result": "0x5208"
}

This represents 21,000 gas units in decimal.

Error Response​

{
  "jsonrpc": "2.0",
  "id": 1,
  "error": {
    "code": -32000,
    "message": "insufficient funds for gas * price + value"
  }
}

Common Use Cases​

1. Pre-Transaction Cost Calculator​

Calculate total transaction costs before execution:

async function calculateTransactionCost(from, to, value, data = '0x') {
  const tx = { from, to, value, data };
  
  try {
    const gasEstimate = await provider.estimateGas(tx);
    const feeData = await provider.getFeeData();
    
    // Calculate different fee scenarios
    const scenarios = {
      low: {
        gasLimit: gasEstimate,
        maxFeePerGas: feeData.gasPrice, // Fallback to legacy
        cost: gasEstimate * feeData.gasPrice
      },
      standard: {
        gasLimit: gasEstimate,
        maxFeePerGas: feeData.maxFeePerGas,
        cost: gasEstimate * feeData.maxFeePerGas
      },
      fast: {
        gasLimit: gasEstimate,
        maxFeePerGas: feeData.maxFeePerGas * 150n / 100n, // 50% higher
        cost: gasEstimate * (feeData.maxFeePerGas * 150n / 100n)
      }
    };
    
    return {
      success: true,
      gasEstimate: gasEstimate.toString(),
      scenarios: Object.entries(scenarios).reduce((acc, [key, scenario]) => {
        acc[key] = {
          gasLimit: scenario.gasLimit.toString(),
          maxFeePerGas: formatUnits(scenario.maxFeePerGas, 'gwei') + ' gwei',
          cost: formatEther(scenario.cost) + ' AVAX',
          costUSD: null // Add USD conversion if needed
        };
        return acc;
      }, {})
    };
  } catch (error) {
    return {
      success: false,
      error: error.message
    };
  }
}

2. Smart Contract Gas Profiler​

Profile gas usage for different contract methods:

async function profileContractMethods(contractAddress, abi, testCases) {
  const contract = new Contract(contractAddress, abi, provider);
  const results = [];
  
  for (const testCase of testCases) {
    const { method, params, from } = testCase;
    
    try {
      // Encode function data
      const txData = contract.interface.encodeFunctionData(method, params);
      
      const tx = {
        from: from,
        to: contractAddress,
        data: txData
      };
      
      const gasEstimate = await provider.estimateGas(tx);
      const gasPrice = await provider.getGasPrice();
      
      results.push({
        method: method,
        params: params,
        gasEstimate: gasEstimate.toString(),
        estimatedCost: formatEther(gasEstimate * gasPrice) + ' AVAX',
        success: true
      });
      
    } catch (error) {
      results.push({
        method: method,
        params: params,
        error: error.message,
        success: false
      });
    }
  }
  
  // Calculate statistics
  const successful = results.filter(r => r.success);
  const gasEstimates = successful.map(r => Number(r.gasEstimate));
  
  const stats = {
    totalMethods: results.length,
    successfulMethods: successful.length,
    averageGas: gasEstimates.reduce((sum, gas) => sum + gas, 0) / gasEstimates.length,
    maxGas: Math.max(...gasEstimates),
    minGas: Math.min(...gasEstimates)
  };
  
  return { results, stats };
}

3. Gas Optimization Advisor​

Provide gas optimization recommendations:

async function gasOptimizationAdvisor(transactions) {
  const advice = [];
  
  for (const tx of transactions) {
    try {
      const baseEstimate = await provider.estimateGas(tx);
      
      // Test different optimization strategies
      const optimizations = {};
      
      // 1. Test with explicit gas limit
      if (!tx.gas) {
        optimizations.explicitGasLimit = {
          suggestion: "Add explicit gas limit",
          gasLimit: Math.ceil(Number(baseEstimate) * 1.1).toString(),
          rationale: "Explicit gas limits prevent estimation failures"
        };
      }
      
      // 2. Test with reduced value for contract calls
      if (tx.data && tx.value && tx.value > 0n) {
        try {
          const reducedValueTx = { ...tx, value: 0n };
          const reducedEstimate = await provider.estimateGas(reducedValueTx);
          
          if (reducedEstimate < baseEstimate) {
            optimizations.reduceValue = {
              suggestion: "Consider reducing transaction value",
              gasReduction: (Number(baseEstimate) - Number(reducedEstimate)).toString(),
              rationale: "Lower values may reduce gas consumption"
            };
          }
        } catch (e) {
          // Ignore - reduction not possible
        }
      }
      
      // 3. Check if method is view/pure (should use eth_call instead)
      if (tx.data) {
        try {
          await provider.call(tx);
          optimizations.useCall = {
            suggestion: "Use eth_call instead of transaction",
            gasReduction: baseEstimate.toString(),
            rationale: "This appears to be a read-only operation"
          };
        } catch (e) {
          // Not a read-only operation
        }
      }
      
      advice.push({
        transaction: tx,
        baseGasEstimate: baseEstimate.toString(),
        optimizations: optimizations,
        hasOptimizations: Object.keys(optimizations).length > 0
      });
      
    } catch (error) {
      advice.push({
        transaction: tx,
        error: error.message,
        success: false
      });
    }
  }
  
  return advice;
}

4. Network Congestion Gas Predictor​

Predict optimal gas prices based on network conditions:

async function predictOptimalGas(urgency = 'standard') {
  const currentBlock = await provider.getBlock('latest');
  const feeData = await provider.getFeeData();
  
  // Analyze recent blocks for congestion
  const recentBlocks = await Promise.all(
    Array.from({ length: 10 }, (_, i) => 
      provider.getBlock(currentBlock.number - i)
    )
  );
  
  const avgUtilization = recentBlocks.reduce(
    (sum, block) => sum + (Number(block.gasUsed) / Number(block.gasLimit)), 0
  ) / recentBlocks.length;
  
  // Base recommendations
  const recommendations = {
    slow: {
      multiplier: 0.9,
      description: "Low priority, may take longer",
      expectedTime: "30-60 seconds"
    },
    standard: {
      multiplier: 1.0,
      description: "Normal priority",
      expectedTime: "10-20 seconds"
    },
    fast: {
      multiplier: 1.3,
      description: "High priority",
      expectedTime: "5-10 seconds"
    },
    instant: {
      multiplier: 1.6,
      description: "Highest priority",
      expectedTime: "2-5 seconds"
    }
  };
  
  // Adjust based on network congestion
  const congestionMultiplier = avgUtilization > 0.8 ? 1.2 : 
                               avgUtilization < 0.3 ? 0.8 : 1.0;
  
  const selectedRec = recommendations[urgency];
  const adjustedMultiplier = selectedRec.multiplier * congestionMultiplier;
  
  const recommendedMaxFee = feeData.maxFeePerGas * BigInt(Math.floor(adjustedMultiplier * 100)) / 100n;
  const recommendedPriorityFee = feeData.maxPriorityFeePerGas * BigInt(Math.floor(adjustedMultiplier * 100)) / 100n;
  
  return {
    urgency: urgency,
    networkUtilization: (avgUtilization * 100).toFixed(1) + '%',
    congestionLevel: avgUtilization > 0.8 ? 'High' : avgUtilization < 0.3 ? 'Low' : 'Medium',
    recommendations: {
      maxFeePerGas: recommendedMaxFee,
      maxPriorityFeePerGas: recommendedPriorityFee,
      maxFeePerGasGwei: formatUnits(recommendedMaxFee, 'gwei') + ' gwei',
      maxPriorityFeePerGasGwei: formatUnits(recommendedPriorityFee, 'gwei') + ' gwei'
    },
    description: selectedRec.description,
    expectedConfirmationTime: selectedRec.expectedTime
  };
}

Performance Optimization​

Batch Gas Estimations​

Estimate gas for multiple transactions efficiently:

async function batchGasEstimations(transactions) {
  const batch = transactions.map((tx, i) => ({
    jsonrpc: '2.0',
    method: 'eth_estimateGas',
    params: [tx],
    id: i
  }));
  
  const response = await fetch('https://api-avalanche-mainnet-archive.n.dwellir.com/YOUR_API_KEY/ext/bc/C/rpc', {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify(batch)
  });
  
  const results = await response.json();
  
  return results.map((result, index) => ({
    transactionIndex: index,
    success: !result.error,
    gasEstimate: result.result ? parseInt(result.result, 16) : null,
    error: result.error?.message
  }));
}

Error Handling​

Common errors and solutions:

Error CodeDescriptionSolution
-32000Insufficient fundsCheck account balance
-32000Execution revertedReview contract logic and parameters
-32602Invalid transaction objectValidate transaction fields
async function safeGasEstimate(tx, maxRetries = 3) {
  for (let i = 0; i < maxRetries; i++) {
    try {
      const gasEstimate = await provider.estimateGas(tx);
      return { success: true, gasEstimate };
    } catch (error) {
      if (error.message.includes('insufficient funds')) {
        return { 
          success: false, 
          error: 'Insufficient balance for transaction',
          suggestion: 'Check account balance and reduce transaction value'
        };
      }
      
      if (error.message.includes('execution reverted')) {
        return {
          success: false,
          error: 'Transaction would revert',
          suggestion: 'Check contract requirements and parameters'
        };
      }
      
      if (i === maxRetries - 1) {
        return { success: false, error: error.message };
      }
      
      await new Promise(resolve => setTimeout(resolve, 1000));
    }
  }
}

Need help? Contact our support team or check the Avalanche documentation.