estimate_cycle - Nervos

Example code for the estimate_cycle JSON-RPC method. Complete guide on how to use estimate_cycle JSON-RPC in GetBlock Web3 documentation.

Returns the estimated CKB-VM cycles needed to execute a transaction's scripts. Like Ethereum's eth_estimateGas but for CKB-VM cycles instead of gas. The transaction does not have to be valid for execution at the moment of the call.

Parameters

Parameter	Type	Required	Description
tx	Transaction	Yes	Transaction to estimate cycles for

Request Example

cURL

curl --location --request POST 'https://go.getblock.io/<ACCESS-TOKEN>/' \
--header 'Content-Type: application/json' \
--data-raw '{
    "jsonrpc": "2.0",
    "method": "estimate_cycles",
    "params": [
        {
            "version": "0x0",
            "cell_deps": [],
            "header_deps": [],
            "inputs": [],
            "outputs": [],
            "outputs_data": [],
            "witnesses": []
        }
    ],
    "id": "getblock.io"
}'

JavaScript (Axios)

import axios from 'axios';

const data = JSON.stringify({
    "jsonrpc": "2.0",
    "method": "estimate_cycles",
    "params": [
        {
            "version": "0x0",
            "cell_deps": [],
            "header_deps": [],
            "inputs": [],
            "outputs": [],
            "outputs_data": [],
            "witnesses": []
        }
    ],
    "id": "getblock.io"
});

const config = {
    method: 'post',
    url: 'https://go.getblock.io/<ACCESS-TOKEN>/',
    headers: {
        'Content-Type': 'application/json'
    },
    data: data
};

axios(config)
    .then(response => console.log(JSON.stringify(response.data, null, 2)))
    .catch(error => console.log(error));

Python (Requests)

import requests
import json

url = "https://go.getblock.io/<ACCESS-TOKEN>/"

payload = json.dumps({
    "jsonrpc": "2.0",
    "method": "estimate_cycles",
    "params": [
        {
            "version": "0x0",
            "cell_deps": [],
            "header_deps": [],
            "inputs": [],
            "outputs": [],
            "outputs_data": [],
            "witnesses": []
        }
    ],
    "id": "getblock.io"
})

headers = {
    'Content-Type': 'application/json'
}

response = requests.post(url, headers=headers, data=payload)
print(response.text)

Rust (Reqwest)

use reqwest::Client;
use serde_json::json;

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let client = Client::new();

    let payload = json!({
        "jsonrpc": "2.0",
        "method": "estimate_cycles",
        "params": [
                {
                        "version": "0x0",
                        "cell_deps": [],
                        "header_deps": [],
                        "inputs": [],
                        "outputs": [],
                        "outputs_data": [],
                        "witnesses": []
                }
        ],
        "id": "getblock.io"
});

    let response = client
        .post("https://go.getblock.io/<ACCESS-TOKEN>/")
        .header("Content-Type", "application/json")
        .json(&payload)
        .send()
        .await?;

    let result: serde_json::Value = response.json().await?;
    println!("{:#?}", result);

    Ok(())
}

Response Example

{
    "jsonrpc": "2.0",
    "id": "getblock.io",
    "result": {
        "cycles": "0x3a980"
    }
}

Response Parameters

Field	Type	Description
result.cycles	Uint64	Estimated CKB-VM cycles consumed (hex)

Use Cases

• Wallet pre-flight checks before broadcasting a transaction

• Computing transaction fees based on cycle count

• Detecting transactions that would exceed cycle limits

Error Handling

Status Code	Error Message	Cause
403	Forbidden	Missing or invalid <ACCESS-TOKEN>
-32602	Invalid params	Request parameters are missing or malformed
-32601	Method not found	Method does not exist or is not enabled on this node
-32603	Internal error	Server-side error while processing the request
429	Too Many Requests	Rate limit exceeded for your plan
-32000	Transaction failed verification	Scripts in the transaction would revert; estimation cannot complete

SDK Integration

@ckb-lumos/lumos

import { RPC } from '@ckb-lumos/rpc';

const rpc = new RPC('https://go.getblock.io/<ACCESS-TOKEN>/');

// Lumos provides typed methods on `rpc` (e.g. rpc.getTipHeader(), rpc.getBlock(hash)).
// For raw access to any CKB RPC method:
const result = await rpc.send('estimate_cycles', [{"version": "0x0", "cell_deps": [], "header_deps": [], "inputs": [], "outputs": [], "outputs_data": [], "witnesses": []}]);
console.log(result);

ckb-sdk-python / requests

# Using the official CKB SDK Python (ckb-sdk-python).
# For methods not yet wrapped, fall back to raw requests.
import requests

response = requests.post('https://go.getblock.io/<ACCESS-TOKEN>/', json={
    'jsonrpc': '2.0',
    'id': 'getblock.io',
    'method': 'estimate_cycles',
    'params': [{"version": "0x0", "cell_deps": [], "header_deps": [], "inputs": [], "outputs": [], "outputs_data": [], "witnesses": []}]
}})
print(response.json())