Compute Units (CUs)

What is a Compute Unit (CU)?

A Compute Unit (CU) measures the computational resources (CPU, RAM, disk I/O, network) consumed by an API request. This provides fair pricing where simple calls cost less than complex operations.

Examples:

• eth_blockNumber: ~10 CUs (simple, fast)
• eth_call: ~26 CUs (standard operation)
• eth_getLogs: 75-500 CUs (scales with range)
• trace_transaction: 1,000 CUs (trace operation)
• debug_traceTransaction: 5,000 CUs (very high compute)

How CUs Work

A Compute Unit (CU) measures the computational resources (CPU, RAM, disk I/O, network) consumed by an API request. This provides fair pricing where simple calls cost less than complex operations.

Why CU-Based Pricing?

Traditional "requests per minute" pricing treats all API calls equally, even though:

• eth_blockNumber takes milliseconds and minimal compute
• debug_traceBlockByNumber can take 30+ seconds and consume 5000x more resources

CU-based pricing ensures:

• Fair costs - Pay for actual compute used
• Predictable billing - Understand costs before you call
• No surprise bills - Separate trace CU pools prevent accidents
• Industry standard - Matches Alchemy, QuickNode, Infura

CU Costs by Method Type

Standard Methods (Low CU)

Method	CU Cost	Description
eth_blockNumber	10	Latest block number
eth_gasPrice	10	Current gas price
eth_chainId	5	Chain identifier
net_version	5	Network version

Common Methods (Medium CU)

Method	CU Cost	Description
eth_getBalance	15	Account balance
eth_call	26	Contract read call
eth_estimateGas	87	Gas estimation
eth_getBlockByNumber	21-36	Block data
eth_getLogs	75-500	Event logs (scales with range)

Gas & Price API Methods (Low CU - Value-Add Features)

Method	CU Cost	Description
Gas price query (single chain)	5	Current gas prices for one chain
Gas price comparison (multi-chain)	10	Compare gas across multiple chains
Historical gas query (per day)	20	Historical gas data per day requested
Gas optimization recommendation	15	Gas optimization suggestions
Token price query	5	Current token price
Historical price query (per day)	15	Historical price data per day
Price comparison (multi-source)	10	Compare prices across exchanges
Market data query	10	Global market statistics

Included Value-Adds

Gas and price API operations are included in all paid tiers at no extra cost. Competitors charge $25-75/month extra for these features. At Axol, they're baked in.

Trace Methods (Very High CU)

Method	CU Cost	Description
trace_transaction	1,000	Single transaction trace
trace_block	2,500	Full block trace
debug_traceCall	3,000	Simulate and trace call
debug_traceTransaction	5,000	Detailed debug trace
debug_traceBlockByNumber	50,000	Full block debug (50x multiplier!)

WebSocket Subscriptions

Type	CU Cost	Description
newHeads	40/event	New block headers
logs	40/event	Event logs subscription
newPendingTransactions	40/event	Pending tx hashes

Average Request: ~25 CUs across typical usage patterns

CU Pools

Standard CU Pool

• Covers all eth_*, net_*, web3_* methods
• Includes WebSocket subscriptions
• Monthly allocation based on your tier

Trace CU Pool (Separate)

• Covers all trace_* and debug_* methods
• Separate allocation to prevent accidental overages
• Available on Starter tier and above

Why Separate Pools?

Trace and debug methods can consume 50-5000x more resources than standard calls. Without separation, one accidental debug_traceBlockByNumber could cost more than 100 regular users' monthly usage.

Monitoring Your Usage

Response Headers

Every API response includes CU information:

X-RateLimit-CU-Limit: 2000000000
X-RateLimit-CU-Remaining: 1950000000
X-RateLimit-CU-Reset: 1704153600
X-RateLimit-Trace-CU-Limit: 100000000
X-RateLimit-Trace-CU-Remaining: 95000000

Dashboard

Access real-time usage at app.axol.io/dashboard:

• Current month CU usage (standard + trace)
• Projected overage cost
• Historical usage charts
• Cost breakdown by method

Estimating Usage

CU Usage Calculator

Estimate your monthly Compute Unit consumption

DeFi Dapp

Token balances, swap quotes, gas tracking

NFT Platform

Token metadata, transfers, marketplace activity

Wallet App

Balance checks, transaction monitoring

Custom

Enter your own usage

Simple calls (10 CUs each)

e.g., eth_blockNumber

Standard calls (26 CUs each)

e.g., eth_call

Log queries (75 CUs each)

e.g., eth_getLogs

Block receipts (250 CUs each)

e.g., eth_getBlockReceipts

WebSocket events (40 CUs each)

e.g., newHeads, logs

Estimated CUs/month:30.5M CUs

Free tier limit:150M CUs

Your usage fits in the Free tier!

With 30.5M CUs/month estimated, you're within the 150M free tier limit.

Get Started Free

Formula: Total CUs = (Simple calls × 10) + (Standard calls × 25) + (Complex calls × 100)

Example: If you make:

• 1M eth_blockNumber calls = 10M CUs
• 500K eth_call calls = 13M CUs
• 100K eth_getLogs calls = 7.5M CUs
• Total: 30.5M CUs/month = Fits in Free tier