---
title: Credit units and eligibility
description: Understand dollar face value, integer precision, scoped grants, expiry and held credit amounts.
---

One credit has a face value of **$0.01**. One credit equals **1,000,000 microcredits**. APIs transport microcredits as decimal integer strings, preserving sub-cent precision without floating point rounding.

Grant amounts, eligible services and expiry come from the authenticated ledger. Do not assume a welcome balance: inspect the grant actually issued to your account. Promotional credits are non-transferable and cannot be cashed out.

Available balances exclude held amounts. Eligibility depends on expiry, issuer scope, service/category restrictions and owner caps. A positive total balance does not imply every service is covered.

[Payment flow](/docs/payments) explains insufficient eligible credits and runtime approval. [Protocol](/docs/spec) describes vouchers and receipts.