# Solidity Devs do something! Save some gas

Here is a list of tips for reducing gas usage for your solidity smart contract.

There are a lot of points out there and suggested by many masters in this field.

I will try my best to consolidate the majority of them here 👇

**Will update this blog periodically, so save it for further reference

# Don't Initialize Variables with Default Value

If the variable is not set/initialized, it is assumed to have a default value (0, false, 0x0, etc., depending on the data type). 

If you explicitly initialize it with its default value, you are just wasting gas.

![image.png](https://cdn.hashnode.com/res/hashnode/image/upload/v1653584464487/4_KSbEq86.png align="left")


# Reading and writing local variables is cheap, whereas reading and writing state variables stored in contract storage are expensive.


![image.png](https://cdn.hashnode.com/res/hashnode/image/upload/v1653584488454/nsp4PTwCo.png align="left")

# Pack your variables!

![image.png](https://cdn.hashnode.com/res/hashnode/image/upload/v1653584503103/nd5UaFsBd.png align="left")

# uint8 is not always cheaper than uint256

![image.png](https://cdn.hashnode.com/res/hashnode/image/upload/v1653584519841/T2ZfEVB8w.png align="left")

# Mark immutable variables

![image.png](https://cdn.hashnode.com/res/hashnode/image/upload/v1653584533875/bBOCidz4-.png align="left")

# Public vs External (External is cheaper)

The public modifier is equivalent to external + internal. In other words, both public and external can be called from outside your contract (like MetaMask), but only the public can be called from other functions inside your contract.

![image.png](https://cdn.hashnode.com/res/hashnode/image/upload/v1653584547555/YWpaZPM-S.png align="left")

Similarly, if a function is only called by other functions in the contract using the "internal" modifier is good it is cheaper to call


# prefix increment is better than postfix increment.

Note to be careful using this optimization whenever the expression's return value is used afterwards, e.g. `uint a = i++` and `uint a = ++i` result in different values for `a`.

![image.png](https://cdn.hashnode.com/res/hashnode/image/upload/v1653584584273/fkAHhq-eG.png align="left")

Another benefit of using this method👇

When using any kind of counter (like `_tokenId`), starting it off at `1` instead of `0` will make the first mint slightly cheaper. In general, writing a value to a slot that doesn’t have one will be more expensive than writing to one that does, so keep that in mind.


# Delete variables that you don’t need.

In Ethereum, you get a gas refund for freeing up storage space. If you don’t need a variable anymore, you should delete it using the delete keyword provided by solidity or by setting it to its default value.