Percent

The Percent class represents a percentage value as a fraction.

Import

import { Percent } from '@uniswap/sdk-core-next'

Constructor

new Percent(numerator: BigintIsh, denominator?: BigintIsh)

Parameters

Name	Type	Default	Description
`numerator`	`BigintIsh`	-	The numerator
`denominator`	`BigintIsh`	`1n`	The denominator

Example

import { Percent } from '@uniswap/sdk-core-next'
 
// 50% = 50/100
const halfPercent = new Percent(50, 100)
 
// 0.5% = 50/10000 (common for slippage)
const slippage = new Percent(50, 10000)
 
// 1% = 1/100
const onePercent = new Percent(1, 100)
 
// 100% = 1/1 or 100/100
const fullPercent = new Percent(1)
 
// Display
halfPercent.toSignificant(2)  // "50"
slippage.toSignificant(2)     // "0.5"
onePercent.toFixed(2)         // "1.00"

Common Percentages

import { Percent } from '@uniswap/sdk-core-next'
 
// Slippage tolerances
const SLIPPAGE_05 = new Percent(50, 10000)  // 0.5%
const SLIPPAGE_1 = new Percent(100, 10000)  // 1%
const SLIPPAGE_5 = new Percent(500, 10000)  // 5%
 
// Fee percentages
const FEE_001 = new Percent(1, 10000)    // 0.01%
const FEE_005 = new Percent(5, 10000)    // 0.05%
const FEE_03 = new Percent(30, 10000)    // 0.3%
const FEE_1 = new Percent(100, 10000)    // 1%

Properties

`isPercent`

readonly isPercent: true

Type discriminator to identify Percent instances.

Methods

All arithmetic methods return Percent instances:

`add(other)`

add(other: Fraction | BigintIsh): Percent

`subtract(other)`

subtract(other: Fraction | BigintIsh): Percent

`multiply(other)`

multiply(other: Fraction | BigintIsh): Percent

`divide(other)`

divide(other: Fraction | BigintIsh): Percent

`toSignificant(significantDigits?, format?, rounding?)`

toSignificant(
  significantDigits?: number,  // default: 5
  format?: { groupSeparator?: string },
  rounding?: Rounding
): string

Returns the percentage as a string (multiplied by 100).

const p = new Percent(1, 200) // 0.5%
p.toSignificant(2) // "0.5"

`toFixed(decimalPlaces?, format?, rounding?)`

toFixed(
  decimalPlaces?: number,  // default: 2
  format?: { groupSeparator?: string },
  rounding?: Rounding
): string

Returns the percentage with fixed decimals.

const p = new Percent(1, 200)
p.toFixed(2) // "0.50"
p.toFixed(4) // "0.5000"

Example: Slippage Calculation

import { CurrencyAmount, Percent, Token } from '@uniswap/sdk-core-next'
 
const USDC = new Token(1, '0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48', 6, 'USDC')
 
// Expected output from a trade
const expectedOutput = CurrencyAmount.fromRawAmount(USDC, 1000_000000n) // 1000 USDC
 
// Slippage tolerance
const slippageTolerance = new Percent(50, 10000) // 0.5%
 
// Calculate minimum output
// minOutput = expectedOutput * (1 - slippage)
const slippageAdjustment = new Percent(1).subtract(slippageTolerance)
const minOutput = expectedOutput.multiply(slippageAdjustment)
 
console.log(`Expected: ${expectedOutput.toSignificant(6)} USDC`)  // "1000"
console.log(`Slippage: ${slippageTolerance.toSignificant(2)}%`)  // "0.5"
console.log(`Minimum:  ${minOutput.toSignificant(6)} USDC`)      // "995"
 
// Or calculate maximum input for exact output trades
const expectedInput = CurrencyAmount.fromRawAmount(USDC, 1000_000000n)
const maxInput = expectedInput.multiply(new Percent(1).add(slippageTolerance))
 
console.log(`Maximum input: ${maxInput.toSignificant(6)} USDC`)  // "1005"

Example: Price Impact

import { Percent } from '@uniswap/sdk-core-next'
 
// Price impact thresholds
const LOW_PRICE_IMPACT = new Percent(1, 100)     // 1%
const MEDIUM_PRICE_IMPACT = new Percent(3, 100)  // 3%
const HIGH_PRICE_IMPACT = new Percent(5, 100)    // 5%
 
function getPriceImpactSeverity(priceImpact: Percent): string {
  if (priceImpact.lessThan(LOW_PRICE_IMPACT)) {
    return 'low'
  }
  if (priceImpact.lessThan(MEDIUM_PRICE_IMPACT)) {
    return 'medium'
  }
  if (priceImpact.lessThan(HIGH_PRICE_IMPACT)) {
    return 'high'
  }
  return 'very high'
}
 
const impact = new Percent(25, 1000) // 2.5%
console.log(getPriceImpactSeverity(impact)) // "medium"