---
title: "True APR (Reg Z / TILA) from the note rate plus financed fees — the real cost of borrowing."
method: POST
path: "/v1/lending/apr"
tags: ["Lending"]
---

# True APR (Reg Z / TILA) from the note rate plus financed fees — the real cost of borrowing.

`POST /v1/lending/apr`

## Request

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

True APR (Reg Z / TILA) from the note rate plus financed fees — the real cost of borrowing.

Payment: x402 ($0.05 USDC on eip155:8453). Call unpaid to receive an HTTP 402 with requirements, then retry with the PAYMENT-SIGNATURE header. Method: payment on the note; solve monthly i where amountFinanced = payment·(1−(1+i)⁻ⁿ)/i; APR = i·12

## Request body

- object
  - `loanAmount` number, required
  - `noteRatePct` number, required
  - `feesFinanced` number
  - `termMonths` number, required

## 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)