---
title: "Base gas price and fee suggestions"
method: GET
path: "/api/x402/base/gas"
tags: ["base-onchain-data", "x402-paid"]
---

# Base gas price and fee suggestions

`GET /api/x402/base/gas`

## Request

- Base URL: `https://ontarioprotocol.com`
- URL: `https://ontarioprotocol.com/api/x402/base/gas`
- Auth: none required

Next-block base fee, priority-fee p25/p50/p90 over the last 20 blocks, slow, normal and fast maxFeePerGas suggestions, L1 data-fee upper bounds and total cost estimates for an ETH and an ERC-20 transfer, live from Base RPC. 0.0015 USDC on Base; a failed read is not charged. Estimates, not inclusion guarantees.

## Query parameters

- `blocks` integer

## Response `200`

Successful live read; the payment settled

- object
  - `base_fee_wei` string, required
  - `block` integer, required
  - `estimate_includes_l1_fee` boolean
  - `estimated_total_wei` object, required
    - `erc20_transfer` string, required
    - `eth_transfer` string, required
  - `l1_fee_upper_bound_wei` object, nullable, required
  - `network` 'eip155:8453', required
  - `priority_fee_wei` object, required
    - `p25` string, required
    - `p50` string, required
    - `p90` string, required
  - `read_at` string, required
  - `schema` 'ontario.base_gas.v1', required
  - `source` 'Base RPC', required
  - `suggested` object, required
    - `fast` object, required
      - `max_fee_per_gas` string, required
      - `max_priority_fee_per_gas` string, required
    - `normal` object, required
      - `max_fee_per_gas` string, required
      - `max_priority_fee_per_gas` string, required
    - `slow` object, required
      - `max_fee_per_gas` string, required
      - `max_priority_fee_per_gas` string, required

## Other responses

- `402`: x402 payment challenge (every unsigned request)
- `503`: Base RPC unavailable; payment not settled

## Changes

- **2026-10-25** `39920cff9aa5`: 1 info
  - endpoint added

[Operation history](https://skmtc.dev/ontarioprotocol/apis/ontario-protocol-x402-api/changes/api/x402/base/gas/get.md)

---

[API](https://skmtc.dev/ontarioprotocol/apis/ontario-protocol-x402-api.md) - [All operations](https://skmtc.dev/ontarioprotocol/apis/ontario-protocol-x402-api/llms.txt) - [OpenAPI document](https://skmtc.dev/ontarioprotocol/apis/ontario-protocol-x402-api/revisions/c4bb7fd32b2f?raw)