Sui is already known for having very low gas fees compared to big names like Ethereum or Solana, but “low” doesn’t mean “free.” If you’re building a large-scale app — especially one that handles thousands of transactions per day — even a tiny inefficiency in each transaction will eventually cost you.

A lot of developers fall into the trap of thinking: “If I just put all my actions into one big transaction, it’ll be more efficient.” In Sui, that’s not always true. Every time you add more input objects (the on-chain assets your transaction reads or changes), the complexity goes up. This can push your transaction past the gas budget or cause “out-of-gas” errors, especially when running bulk operations.

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Step 1: Profile Before You Optimize

The first step toward gas efficiency is understanding your current usage. Sui gives you an easy way to do this using the CLI’s --gas-budget flag. By simulating your transactions at different gas budgets, you can see how much gas they actually require. This helps you spot whether a single “mega-transaction” is eating way more gas than it should.

For example:

sui client call --function my_function \
--module my_module \
--package <package_id> \
--args <args_here> \
--gas-budget 2000

If you see the transaction failing unless you set a huge gas budget, that’s your red flag.

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Step 2: Break Down Large Transactions

Instead of cramming everything into one go, split it into smaller logical groups. Let’s say your dApp is minting new NFTs, transferring them to users, and updating some metadata — all in one transaction. That’s three separate operations, each with its own object reads and writes.

A better approach:

• Transaction 1 → Mint NFTs
• Transaction 2 → Transfer NFTs
• Transaction 3 → Update metadata

By breaking them apart, you reduce the number of input objects in each step, which lowers the chance of hitting the gas limit or object version errors.

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Step 3: Batch Signatures in the SDK

If you’re using the Sui JavaScript SDK, there’s a hidden gem: you can sign multiple actions in one batch and then send them together. This saves gas by avoiding repeated signature verification, which can add up in high-volume situations.

The process is simple:

1. Create multiple transaction blocks in memory.
2. Sign them all at once.
3. Send them in a single RPC call.

But there’s a catch — you must refresh your object states right before executing the batch. If an object’s version number changes while your transaction is pending, it will fail.

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Step 4: Use Immutable Data for Constants

Here’s a subtle but powerful optimization: immutable data (objects that never change after creation) is free to read in Sui. If you’re storing the same values over and over in mutable objects — like default prices, configuration options, or reference IDs — you’re making your transactions do unnecessary work.

Instead:

• Store those constants as immutable objects once.
• Reference them in your transactions instead of copying them each time.

This way, your transactions don’t waste gas reading or writing the same data repeatedly.

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Step 5: Keep a Gas-Efficiency Mindset

Optimizing for gas isn’t just about saving a few cents; it’s about making your dApp more reliable. When your transactions are lean, they fail less often, run faster, and are easier to debug. Over time, these savings compound — both in terms of money and in smoother user experiences.

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Key Takeaways:

• Profile transactions before optimizing.
• Break big transactions into smaller ones.
• Batch signatures to save on repeated verifications.
• Store constants as immutable to avoid unnecessary gas costs.
• Always refresh object states before sending a transaction.

Master these habits early, and you’ll avoid painful scaling issues later. Sui’s low fees are a gift — but only if you treat them with respect.