Why gas efficiency saves money in Blockchain / Solidity - Visual Breakdown

Concept Flow - Why gas efficiency saves money

User sends transaction

↓

Transaction uses gas units

↓

Gas price set by network

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Total cost = gas units * gas price

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User pays total cost in cryptocurrency

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More efficient code uses fewer gas units

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Lower total cost for user

This flow shows how a blockchain transaction costs money based on gas units used and gas price, so using less gas saves money.

Execution Sample

Blockchain / Solidity

function transfer() public pure returns (uint) {
  uint gasUsed = 21000; // simple transfer
  uint gasPrice = 50; // gwei
  uint cost = gasUsed * gasPrice;
  return cost;
}

Calculates cost of a simple blockchain transfer by multiplying gas used by gas price.

Execution Table

Step	Gas Used	Gas Price (gwei)	Calculation	Cost (gwei)
1	21000	50	21000 * 50	1050000
2	15000	50	15000 * 50	750000
3	10000	50	10000 * 50	500000
Exit	-	-	-	Calculation complete

💡 Cost calculated for different gas usages; lower gas used means lower cost.

Variable Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	Final
gasUsed	undefined	21000	15000	10000	10000
gasPrice	undefined	50	50	50	50
cost	undefined	1050000	750000	500000	500000

Key Moments - 2 Insights

Why does using less gas reduce the cost?

Because cost is gasUsed multiplied by gasPrice, so lowering gasUsed directly lowers total cost, as shown in execution_table rows 1 to 3.

Does changing gasPrice affect cost the same way as gasUsed?

Yes, cost depends on both gasUsed and gasPrice, but in this example gasPrice stays constant to show effect of gasUsed changes (see variable_tracker).

Visual Quiz - 3 Questions

Look at the execution_table, what is the cost when gasUsed is 15000?

A 1050000 gwei

B 750000 gwei

C 500000 gwei

D 15000 gwei

💡 Hint

Check execution_table row 2 under Cost column.

At which step does the cost become 500000 gwei?

A Step 3

B Step 1

C Step 2

D Exit

💡 Hint

Look at execution_table rows and find where Cost is 500000.

If gasPrice doubled to 100 gwei but gasUsed stayed 21000, what would cost be?

A 1050000 gwei

B 420000 gwei

C 2100000 gwei

D 500000 gwei

💡 Hint

Multiply gasUsed 21000 by new gasPrice 100.

Concept Snapshot

Gas cost = gasUsed * gasPrice
Lower gasUsed means lower cost
Gas price is set by network
Efficient code uses less gas
Saves money on blockchain transactions

Full Transcript

When you send a blockchain transaction, it uses gas units. The network sets a gas price. Your total cost is gas units times gas price. Using less gas means you pay less. For example, a simple transfer uses 21000 gas units. If gas price is 50 gwei, cost is 21000 times 50 equals 1050000 gwei. If you optimize code to use 15000 gas units, cost drops to 750000 gwei. This shows why gas efficiency saves money.