diff --git a/.eslintignore b/.eslintignore
index 6e1b5f88..34800870 100644
--- a/.eslintignore
+++ b/.eslintignore
@@ -1,3 +1,9 @@
+*.config.js
+*.config.ts
+package*.json
+.eslintrc.cjs
+bundle*.js
+
 packages/web3-utils
 packages/massa-web3/examples
 packages/massa-web3/code-snippets
@@ -6,10 +12,7 @@ packages/massa-web3/src/utils
 packages/massa-web3/src/web3
 packages/massa-web3/src/index.ts
 packages/massa-web3/test
+
 **/generated/**
 **/dist/**
-**/docs/**
-*.config.js
-*.config.ts
-package*.json
-.eslintrc.cjs
\ No newline at end of file
+**/docs/**
\ No newline at end of file
diff --git a/packages/massa-web3/src/experimental/basicElements/index.ts b/packages/massa-web3/src/experimental/basicElements/index.ts
index 8afd1964..c1ca5487 100644
--- a/packages/massa-web3/src/experimental/basicElements/index.ts
+++ b/packages/massa-web3/src/experimental/basicElements/index.ts
@@ -5,3 +5,4 @@ export * from './operationManager'
 export * from './operation'
 export * from './storage'
 export * from './args'
+export * as Mas from './mas'
diff --git a/packages/massa-web3/src/experimental/basicElements/mas.ts b/packages/massa-web3/src/experimental/basicElements/mas.ts
new file mode 100644
index 00000000..1040c8cf
--- /dev/null
+++ b/packages/massa-web3/src/experimental/basicElements/mas.ts
@@ -0,0 +1,131 @@
+import { FIRST, ONE } from '../utils'
+
+const NB_DECIMALS = 9
+const POWER_TEN = 10
+const SIZE_U256_BIT = 256
+
+export const ERROR_NOT_SAFE_INTEGER = 'value is not a safe integer.'
+export const ERROR_VALUE_TOO_LARGE = 'value is too large.'
+
+export type Mas = bigint
+
+/**
+ * Converts an integer value to the smallest unit of the Massa currency.
+ *
+ * @see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/isSafeInteger#description
+ *
+ * @param value - The integer value.
+ * @returns The value in the smallest unit of the Massa currency.
+ *
+ * @throws An error if the value is not a safe integer.
+ */
+export function fromMas(value: number): Mas {
+  if (!Number.isSafeInteger(value)) {
+    throw new Error(ERROR_NOT_SAFE_INTEGER)
+  }
+
+  return BigInt(value * POWER_TEN ** NB_DECIMALS)
+}
+
+/**
+ * Converts an integer value in milli Massa to the smallest unit of the Massa currency.
+ *
+ * @see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/isSafeInteger#description
+ *
+ * @param value - The value in milli Massa.
+ * @returns The value in the smallest unit of the Massa currency.
+ *
+ * @throws An error if the value is not a safe integer.
+ */
+export function fromMilliMas(value: number): Mas {
+  if (!Number.isSafeInteger(value)) {
+    throw new Error(ERROR_NOT_SAFE_INTEGER)
+  }
+  const milli = 3
+  return BigInt(value * POWER_TEN ** (NB_DECIMALS - milli))
+}
+
+/**
+ * Converts an integer value in micro Massa to the smallest unit of the Massa currency.
+ *
+ * @see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/isSafeInteger#description
+ *
+ * @param value - The value in micro Massa.
+ * @returns The value in the smallest unit of the Massa currency.
+ *
+ * @throws An error if the value is not a safe integer.
+ */
+export function fromMicroMas(value: number): Mas {
+  if (!Number.isSafeInteger(value)) {
+    throw new Error(ERROR_NOT_SAFE_INTEGER)
+  }
+  const micro = 6
+  return BigInt(value * POWER_TEN ** (NB_DECIMALS - micro))
+}
+
+/**
+ * Converts an integer value in nano Massa to the smallest unit of the Massa currency.
+ *
+ * @see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/isSafeInteger#description
+ *
+ * @param value - The value in nano Massa.
+ * @returns The value in the smallest unit of the Massa currency.
+ *
+ * @throws An error if the value is not a safe integer.
+ */
+export function fromNanoMas(value: number): Mas {
+  if (!Number.isSafeInteger(value)) {
+    throw new Error(ERROR_NOT_SAFE_INTEGER)
+  }
+
+  const nano = 9
+  return BigInt(value * POWER_TEN ** (NB_DECIMALS - nano))
+}
+
+/**
+ * Converts a decimal value to the smallest unit of the Massa currency.
+ *
+ * @param value - The decimal value.
+ * @returns The value in the smallest unit of the Massa currency.
+ *
+ * @throws An error if the format is not a decimal.
+ * @throws An error if the value is too large to be represented by an U256 or has too many decimals.
+ */
+export function fromString(value: string): Mas {
+  const parts = value.split('.')
+  // eslint-disable-next-line @typescript-eslint/no-magic-numbers
+  if (parts.length > 2) {
+    throw new Error('invalid format')
+  }
+
+  const integerPart = parts[FIRST]
+  const decimalPart = parts[ONE] || ''
+  if (decimalPart.length > NB_DECIMALS) {
+    throw new Error(ERROR_VALUE_TOO_LARGE)
+  }
+
+  const mas = BigInt(integerPart + decimalPart.padEnd(NB_DECIMALS, '0'))
+  if (mas >= BigInt(ONE) << BigInt(SIZE_U256_BIT)) {
+    throw new Error(ERROR_VALUE_TOO_LARGE)
+  }
+
+  return mas
+}
+
+/**
+ * Converts a value in the smallest unit of the Massa currency to a decimal value.
+ *
+ * @param value - The value in the smallest unit of the Massa currency.
+ * @returns The decimal value.
+ *
+ * @throws An error if the value is too large to be represented by an U256.
+ */
+export function toString(value: Mas): string {
+  if (value >= BigInt(ONE) << BigInt(SIZE_U256_BIT)) {
+    throw new Error(ERROR_VALUE_TOO_LARGE)
+  }
+  const valueString = value.toString()
+  const integerPart = valueString.slice(FIRST, -NB_DECIMALS) || '0'
+  const decimalPart = valueString.slice(-NB_DECIMALS).replace(/0+$/, '')
+  return `${integerPart}${decimalPart.length ? '.' + decimalPart : ''}`
+}
diff --git a/packages/massa-web3/test/experimental/unit/mas.spec.ts b/packages/massa-web3/test/experimental/unit/mas.spec.ts
new file mode 100644
index 00000000..62cf7f1f
--- /dev/null
+++ b/packages/massa-web3/test/experimental/unit/mas.spec.ts
@@ -0,0 +1,40 @@
+import { Mas } from '../../../src/experimental/basicElements'
+
+describe('amount conversion', () => {
+  it('converts from integer', () => {
+    expect(Mas.fromMas(1)).toStrictEqual(1_000_000_000n)
+    expect(Mas.fromMas(1234)).toStrictEqual(1_234_000_000_000n)
+    expect(() => Mas.fromMas(1.1)).toThrow(Mas.ERROR_NOT_SAFE_INTEGER)
+
+    expect(Mas.fromMilliMas(1)).toStrictEqual(1_000_000n)
+    expect(Mas.fromMilliMas(1234)).toStrictEqual(1_234_000_000n)
+    expect(() => Mas.fromMilliMas(1.1)).toThrow(Mas.ERROR_NOT_SAFE_INTEGER)
+
+    expect(Mas.fromMicroMas(1)).toStrictEqual(1_000n)
+    expect(Mas.fromMicroMas(1234)).toStrictEqual(1_234_000n)
+    expect(() => Mas.fromMicroMas(1.1)).toThrow(Mas.ERROR_NOT_SAFE_INTEGER)
+
+    expect(Mas.fromNanoMas(1)).toStrictEqual(1n)
+    expect(Mas.fromNanoMas(1234)).toStrictEqual(1_234n)
+    expect(() => Mas.fromNanoMas(1.1)).toThrow(Mas.ERROR_NOT_SAFE_INTEGER)
+  })
+
+  it('converts from string', () => {
+    expect(Mas.fromString('1')).toStrictEqual(1_000_000_000n)
+    expect(Mas.fromString('1.1')).toStrictEqual(1_100_000_000n)
+    expect(Mas.fromString('01234.56789')).toStrictEqual(1_234_567_890_000n)
+    expect(Mas.fromString('01234.567890000')).toStrictEqual(1_234_567_890_000n)
+    expect(() => Mas.fromString('1.1.1')).toThrow()
+    expect(() => Mas.fromString('0.1234567890')).toThrow()
+    expect(() =>
+      Mas.fromString((BigInt(1) << BigInt(256)).toString())
+    ).toThrow()
+  })
+
+  it('converts to string', () => {
+    expect(Mas.toString(1_000_000_000n)).toStrictEqual('1')
+    expect(Mas.toString(1_100_000_000n)).toStrictEqual('1.1')
+    expect(Mas.toString(1_234_567_890_000n)).toStrictEqual('1234.56789')
+    expect(() => Mas.toString(BigInt(1) << BigInt(256))).toThrow()
+  })
+})