> ## Documentation Index
> Fetch the complete documentation index at: https://voltaire.tevm.sh/llms.txt
> Use this file to discover all available pages before exploring further.

# Uint.fromBigInt

> Create Uint256 from JavaScript BigInt

<Card title="Try it Live" icon="play" href="https://playground.tevm.sh?example=primitives/uint.ts">
  Run Uint examples in the interactive playground
</Card>

<Tabs />

## BigInt Values

JavaScript BigInt provides arbitrary precision integers:

```typescript theme={null}
// Small values
Uint.fromBigInt(0n)
Uint.fromBigInt(1n)
Uint.fromBigInt(255n)

// Large values
Uint.fromBigInt(2n ** 128n)
Uint.fromBigInt(2n ** 255n)

// Maximum
Uint.fromBigInt(2n ** 256n - 1n)
```

<Warning>
  BigInt values must be non-negative and less than 2^256. Negative values and overflow throw errors.
</Warning>

## Range Validation

### Valid Range

```typescript theme={null}
// Minimum: 0
Uint.fromBigInt(0n)

// Maximum: 2^256 - 1
const max = 115792089237316195423570985008687907853269984665640564039457584007913129639935n
Uint.fromBigInt(max)
```

### Out of Range

```typescript theme={null}
// Negative values throw
Uint.fromBigInt(-1n)        // Error: Value cannot be negative
Uint.fromBigInt(-100n)      // Error: Value cannot be negative

// Overflow throws
Uint.fromBigInt(2n ** 256n)     // Error: Value exceeds 2^256 - 1
Uint.fromBigInt(2n ** 257n)     // Error: Value exceeds 2^256 - 1
```

## Usage Patterns

### Computation Results

```typescript theme={null}
// BigInt arithmetic
const a = 100n
const b = 50n
const sum = Uint.fromBigInt(a + b)        // 150
const product = Uint.fromBigInt(a * b)    // 5000

// With validation
function safeFromBigInt(value: bigint): BrandedUint256 | null {
  if (value < 0n || value >= 2n ** 256n) {
    return null
  }
  return Uint.fromBigInt(value)
}
```

### Constants

```typescript theme={null}
// Common Ethereum constants
const ONE_ETHER = Uint.fromBigInt(10n ** 18n)
const ONE_GWEI = Uint.fromBigInt(10n ** 9n)
const MAX_UINT256 = Uint.fromBigInt(2n ** 256n - 1n)
const MAX_UINT128 = Uint.fromBigInt(2n ** 128n - 1n)
```

### Parsing Large Numbers

```typescript theme={null}
// JSON doesn't support BigInt, must parse strings
interface ApiResponse {
  balance: string  // BigInt serialized as string
}

function parseBalance(data: ApiResponse): BrandedUint256 {
  const balanceBigInt = BigInt(data.balance)
  return Uint.fromBigInt(balanceBigInt)
}
```

## See Also

* [from](/primitives/uint256/from) - Universal constructor
* [toBigInt](/primitives/uint256/to-bigint) - Convert to BigInt
* [fromNumber](/primitives/uint256/from-number) - From number