Gas

Gas limit and gas price types for transaction fees

Overview

Gas provides branded types for gas limits and gas prices, preventing common bugs like mixing these values. Includes GasLimit for transaction gas limits and GasPrice for gas prices in wei.

import { GasLimit, GasPrice } from '@voltaire/primitives/Gas'

const limit = GasLimit.from(21000)
const price = GasPrice.fromGwei(20) // 20 gwei

const fee = GasLimit.toBigInt(21000) * GasPrice.toBigInt(price)

Type Definitions

type GasLimitType = bigint & { readonly [brand]: "GasLimit" }
type GasPriceType = bigint & { readonly [brand]: "GasPrice" }

Both types wrap bigint with branding to prevent accidental mixing.

GasLimit

Creating GasLimit

from

Create from number, bigint, or hex string.

const limit1 = GasLimit.from(21000)
const limit2 = GasLimit.from(21000n)
const limit3 = GasLimit.from("0x5208") // 21000 in hex

GasLimit Constants

Pre-defined gas limits for common operations:

import { SIMPLE_TRANSFER, ERC20_TRANSFER, DEFAULT_LIMIT } from '@voltaire/primitives/Gas'

SIMPLE_TRANSFER  // 21000 - ETH transfer
ERC20_TRANSFER   // 65000 - ERC-20 token transfer
DEFAULT_LIMIT    // 30000000 - Block gas limit

GasLimit Methods

toBigInt

Convert to bigint.

const n = GasLimit.toBigInt(21000) // 21000n

toNumber

Convert to number.

const n = GasLimit.toNumber(21000) // 21000

GasPrice

Creating GasPrice

from

Create from wei value (number, bigint, or hex string).

const price1 = GasPrice.from(20_000_000_000)  // 20 gwei in wei
const price2 = GasPrice.from(20_000_000_000n)
const price3 = GasPrice.from("0x4a817c800")   // 20 gwei

fromGwei

Create from gwei (more convenient for typical gas prices).

const price = GasPrice.fromGwei(20)
// Equivalent to: GasPrice.from(20_000_000_000n)

GasPrice Methods

toBigInt

Convert to bigint (wei).

const wei = GasPrice.toBigInt(price) // 20000000000n

toGwei

Convert to gwei.

const gwei = GasPrice.toGwei(price) // 20n

Fee Calculation

Calculate transaction fees with type safety:

import { GasLimit, GasPrice } from '@voltaire/primitives/Gas'

// Simple transfer
const gasLimit = GasLimit.from(21000)
const gasPrice = GasPrice.fromGwei(30)

const fee = GasLimit.toBigInt(gasLimit) * GasPrice.toBigInt(gasPrice)
// fee = 21000n * 30_000_000_000n = 630_000_000_000_000n wei
// = 0.00063 ETH

// EIP-1559 transaction
const maxFeePerGas = GasPrice.fromGwei(50)
const maxPriorityFeePerGas = GasPrice.fromGwei(2)

const maxFee = GasLimit.toBigInt(gasLimit) * GasPrice.toBigInt(maxFeePerGas)
// maxFee = 21000n * 50_000_000_000n = 1_050_000_000_000_000n wei

Common Gas Limits

Operation	Gas Limit
ETH Transfer	21,000
ERC-20 Transfer	~65,000
ERC-20 Approve	~45,000
Uniswap Swap	~150,000
NFT Mint	~100,000
Contract Deploy	Variable

EIP-1559 Gas Model

Post-London fork, gas pricing uses:

// Legacy (pre-EIP-1559)
const legacyTx = {
  gasLimit: GasLimit.from(21000),
  gasPrice: GasPrice.fromGwei(30),
}

// EIP-1559
const eip1559Tx = {
  gasLimit: GasLimit.from(21000),
  maxFeePerGas: GasPrice.fromGwei(50),
  maxPriorityFeePerGas: GasPrice.fromGwei(2),
}

Actual gas price in EIP-1559 is: min(maxFeePerGas, baseFee + maxPriorityFeePerGas)

Namespace Usage

import { GasLimit, GasPrice } from '@voltaire/primitives/Gas'

// Using namespace objects
const limit = GasLimit.from(21000)
const limitBigInt = GasLimit.toBigInt(21000)

const price = GasPrice.from(20_000_000_000n)
const priceGwei = GasPrice.fromGwei(20)
const priceBigInt = GasPrice.toBigInt(priceGwei)

See Also

• Gas (Effect) - Effect.ts integration with Schema validation
• Denomination - Wei/Gwei/Ether conversion
• FeeMarket - EIP-1559 fee calculation
• GasConstants - Operation gas costs
• Transaction - Transaction creation