1 files changed, 29 insertions, 0 deletions
diff --git a/ui/app/pages/send/send-content/send-amount-row/amount-max-button/amount-max-button.utils.js b/ui/app/pages/send/send-content/send-amount-row/amount-max-button/amount-max-button.utils.js
new file mode 100644
index 000000000..a570e49b4
--- /dev/null
+++ b/ui/app/pages/send/send-content/send-amount-row/amount-max-button/amount-max-button.utils.js
@@ -0,0 +1,29 @@
+const {
+  multiplyCurrencies,
+  subtractCurrencies,
+} = require('../../../../../helpers/utils/conversion-util')
+const ethUtil = require('ethereumjs-util')
+
+function calcMaxAmount ({ balance, gasTotal, selectedToken, tokenBalance }) {
+  const { decimals } = selectedToken || {}
+  const multiplier = Math.pow(10, Number(decimals || 0))
+
+  return selectedToken
+    ? multiplyCurrencies(
+      tokenBalance,
+      multiplier,
+      {
+        toNumericBase: 'hex',
+        multiplicandBase: 16,
+      }
+    )
+    : subtractCurrencies(
+      ethUtil.addHexPrefix(balance),
+      ethUtil.addHexPrefix(gasTotal),
+      { toNumericBase: 'hex' }
+    )
+}
+
+module.exports = {
+  calcMaxAmount,
+}