---
title: "Convert between APR and APY at any compounding frequency (or continuous)."
method: POST
path: "/v1/crypto/apr-apy"
tags: ["Crypto & DeFi"]
---

# Convert between APR and APY at any compounding frequency (or continuous).

`POST /v1/crypto/apr-apy`

## Request

- Base URL: `` (relative, and it does not resolve against the document’s source URL)
- URL: `/v1/crypto/apr-apy`
- Auth: none declared

Convert between APR and APY at any compounding frequency (or continuous).

Payment: x402 ($0.02 USDC on eip155:8453). Call unpaid to receive an HTTP 402 with requirements, then retry with the PAYMENT-SIGNATURE header. Method: APY = (1+APR/n)^n - 1; APR = n*((1+APY)^(1/n) - 1); continuous uses e^APR-1 / ln(1+APY)

## Request body

- object
  - `direction` 'apr_to_apy' | 'apy_to_apr'
  - `ratePct` number, required
  - `compoundsPerYear` number
  - `compounding` 'periodic' | 'continuous'

## Response `200`

Verified result + provenance (formula, sources, reproducible SHA-256 hash).

## Other responses

- `400`: Invalid input (no charge) — body echoes the JSON Schema.
- `402`: Payment required — PAYMENT-REQUIRED header carries the x402 accepts[] quote.

---

[API](https://skmtc.dev/x402toll/apis/tollbooth-verified-calculators-for-ai-agents.md) · [All operations](https://skmtc.dev/x402toll/apis/tollbooth-verified-calculators-for-ai-agents/llms.txt) · [OpenAPI document](https://skmtc.dev/x402toll/apis/tollbooth-verified-calculators-for-ai-agents/revisions/60cb70a3e1a5?raw)