X402 Price Explanation

This document explains how the pricing is determined when calling the Ace Data Cloud API using X402, and how it relates to the regular Credits pricing on the platform.

Core Conclusion

X402 is not an independent pricing system. Each API call inherently has a cost measured in Credits, which is the only source of pricing shared across all billing methods (API Token deduction, account balance, X402 on-chain payment). X402 simply converts this Credits cost into on-chain USDC at a fixed exchange rate:

1 Credit = 0.095215 USDC (i.e., 95215 atomic USDC, USDC is 6 decimal places)

In other words:

X402 Price (USDC) = The Credits cost of this call × 0.095215

This exchange rate is not arbitrarily set; it equals the platform's optimal tier (bulk) Credits unit price. Therefore, paying with X402 is approximately equivalent to purchasing Credits at the optimal tier price and then consuming them, with no X402 premium, instead directly enjoying the cheapest Credits unit price, without needing to pre-load or use an API Token.

Pricing Basis

Item Value Description
Exchange Rate 1 Credit = 0.095215 USDC A fixed rate set uniformly by the platform
Atomic Unit 1 Credit = 95215 atomic USDC USDC 6 decimal places, atomic = floor(credits × 0.095215 × 1e6)
Minimum Charge 1 atomic USDC ($0.000001) Even with extremely low costs, at least 1 atomic is settled
Pricing Currency USDC Base / SKALE is ERC-20 USDC, Solana is SPL USDC

The conversion is uniformly completed by the platform, and the amounts are consistent across all supported networks (Base, SKALE, Solana); different networks only differ in asset contracts and signature methods, with the same price.

Relationship with Regular Credits Unit Price

Platform Credits are sold in a tiered manner where "the larger the usage, the lower the unit price." When billing by call, X402 uniformly uses the optimal tier unit price:

Purchase/Payment Method Approximate Credits Unit Price Description
Entry / Small Recharge About $0.13 / Credit List price, unit price when buying small amounts of Credits
Bulk / Optimal Tier $0.095215 / Credit The cheapest unit price
X402 Pay-per-call $0.095215 / Credit Always equals the optimal tier price

In other words, X402 settles each call at the optimal tier Credits unit price. Users who buy Credits with small recharges will have a higher unit price than X402; only users with large recharges will have a unit price that matches X402.

Two Pricing Forms: exact and upto

In the 402 response of X402, maxAmountRequired is the amount you need to sign. It has two forms:

  • exact (fixed price): The price can be determined before processing the request (images, videos, music, search, order payment). maxAmountRequired = The Credits cost of this call × 0.095215, which is the amount payable for this call (consistent with cost.amount in the successful response).
  • upto (usage post-measurement): Interfaces like chat completion where "the number of tokens used is only known at the end of the response." maxAmountRequired is a cap (converted from the cap set by this model: cap Credits × 0.095215), and the actual settlement is based on real usage, not exceeding the cap.

For protocol details regarding these two schemes, see exact and upto billing schemes. Below, only pricing is discussed.

Chat (Chat Completion) Pricing

Chat completion is measured as upto: billed based on actual usage of prompt/completion tokens. The price per million (1M) tokens = The Credits cost of this model per 1M tokens × 0.095215, which is completely consistent with the USD unit prices displayed in the platform's public model directory (/api/v1/models?with_pricing=true).

The table below shows the actual prices (taken from the model directory, calculated at the X402 exchange rate), in USD / 1M tokens:

Model Input / 1M Output / 1M upto Cap
gpt-4o-mini $0.0796 $0.3183 1 Credit ($0.095215)
gemini-2.5-flash $0.1591 $1.3262 5 Credits ($0.476074）
gpt-5 / gpt-5.1 $0.6631 $5.3050 20 Credits ($1.904299）
gemini-2.5-pro $0.6631 $5.3050 50 Credits ($4.760750）
gpt-4.1 $1.0610 $4.2440 20 Credits ($1.904299）
claude-sonnet-4-5 $0.6006 $3.0028 50 Credits ($4.760750）
grok-4 $1.5915 $7.9574 10 Credits ($0.952149）
claude-opus-4-1 $3.0028 $15.0140 50 Credits ($4.760750）

Notes:

  • The table shows the unit price measured by token; the cost of a single request = input tokens × input unit price + output tokens × output unit price.
  • The upto cap is the maximum amount allowed to be signed for a single request for that model; it is not the actual deduction, as the vast majority of requests are far below the cap.
  • The cap only determines "the maximum possible deduction," while the actual settlement is calculated based on token usage.

Example: Quotation and Deduction Match (exact)

Below is a real paid call initiated to serp/google using the official X402Client (Base exact). It demonstrates the consistency of the three: 402 quotation, signed amount, and the cost returned in the successful response.

# 1) Unpaid request -> 402, get the quotation (no deduction)
POST /serp/google  ->  402
base/exact maxAmountRequired = 952 atomic = $0.000952 = 0.01 Credit
# 0.01 × 0.095215 = 0.00095215, rounded down to atomic = 952

# 2) Sign 952 atomic X-Payment with wallet, retry
POST /serp/google (X-Payment) -> 200
body.cost = {"amount": 0.000952, "currency": "usdc", "settlement": "authorized"}

The cost.amount (0.000952 USDC) returned in the response is completely consistent with the 402 quote and Credits × 0.095215. The settlement field indicates the settlement status of the payment (authorized = authorized); on-chain settlement is handled by the platform, see the exact and upto billing schemes.

upto Quote Calculation (Chat)

Chat is measured by token. The quote for a request (not the cap) is calculated using the following formula (taking gpt-4o-mini as an example):

Credits = 1e-6 × (0.835733 × prompt_tokens + 3.342933 × completion_tokens)
USDC    = Credits × 0.095215

For a request of 500 prompt + 200 completion tokens:

Credits = 1e-6 × (0.835733 × 500 + 3.342933 × 200) ≈ 0.001086 Credits
Quote USDC ≈ 0.001086 × 0.095215 ≈ $0.0001034

The client signs according to the upto cap (gpt-4o-mini is 1 Credit = 95215 atomic), which is just the maximum possible deduction; the actual quote for this request (approximately $0.0001 in the example) is far below the cap and is settled based on token usage. The on-chain settlement mechanism for upto can be found in the exact and upto billing schemes.

Other Service Prices (Fixed Price exact)

For interfaces like images, videos, music, and search, the price can be determined at the time of the request using exact. The table below shows the actual prices, taken from the online interface's 402 maxAmountRequired for unpaid requests (querying the quote does not incur charges):

Service Example Model / Parameters Credits USDC atomic
Web Search serp/google, ≤10 results 0.01 $0.000952 952
Image nano-banana 0.14 $0.013330 13330
Image gpt-image-1, 1024×1024 0.20 $0.019043 19043
Image flux-dev 0.24 $0.022851 22851
Image midjourney imagine 0.27 $0.025708 25708
Image seedream-4 0.32 $0.030468 30468
Music suno generate 0.55 $0.052368 52368
Music producer generate 0.68 $0.064746 64746
Video luma 1.19 $0.113305 113305
Video hailuo (minimax-hailuo-2-3) 1.72 $0.163769 163769
Video kling-v2-6 std 2.10 $0.199951 199951
Video kling-v3 std 4.20 $0.399903 399903
Video veo-3 text→video 5.00 $0.476074 476074
Video seedance-1-0-pro, 1080p / 5s 5.60 $0.533204 533204
Video wan2.6-t2v 13.50 $1.285402 1285402

Notes:

  • The prices for the same service vary with model, resolution, duration, and action (especially for video). The table shows the actual values under a specific set of parameters, for reference only.
  • For these fixed-price (exact) interfaces, the maxAmountRequired in the 402 response for this request is the amount due (consistent with the cost.amount in a successful response, as tested in the previous section).
  • Each price is obtained by rounding down Credits × 0.095215 to the atomic unit (see the pricing benchmark above), using the same conversion as for chat. Due to floating-point representation and rounding, some values may differ from the naive product by 1 atomic ($0.000001), and the 402 returned value shall prevail.

Order Payment Price

When using the X402 payment console to pay for orders (purchase packages / recharge Credits), the price is based on what is displayed on the order page, and the 402 maxAmountRequired is the final signature basis. The order payment process goes through the platform API and requires an account token, see the Order Payment Tutorial.

A real example from the order payment tutorial (purchasing 10 Credits):

description Ace Data Cloud Credits x 10.0
created price 1.26          # Order creation price (USD)
settled    1.20 USDC        # Final signature/settlement amount (= 402 maxAmountRequired)
            = 1200000 atomic USDC

Note: Pay-per-call (as mentioned in Chat / Other Services) and order payment are two different paths. Pay-per-call uniformly uses the optimal unit price of 0.095215/Credit; order payment is priced according to the package, and the difference between the creation price and the final settlement amount is based on the Order Payment Tutorial.

How to Get Prices in Real-Time

Prices vary with models and parameters, please obtain them in real-time through programming, do not hard-code:

  • Pay-per-call price: Make a request to the target API without X-Payment (and without Authorization), and read the returned 402 accepts[].maxAmountRequired. This step will not incur charges. For exact interfaces, it is the final price; for upto interfaces (chat), it is the cap, settled based on usage.
  • Chat per token unit price: GET https://platform.acedata.cloud/api/v1/models?with_pricing=true&type=chat, read each model's pricing.input_usd / pricing.output_usd (calculated according to credit_usd_rate).
  • Conversion verification: atomic = floor(Credits × 0.095215 × 1e6), USDC = atomic / 1e6 (i.e., USDC ≈ Credits × 0.095215).

Minimum request example to get prices:

curl -sS -X POST https://api.acedata.cloud/midjourney/imagine \
  -H 'Content-Type: application/json' \
  -d '{"prompt": "a cat"}'
# Returns 402, accepts[].maxAmountRequired is the price for this (exact) call

Summary

  • X402 price = The cost of Credits for this call × 0.095215, which is the same price as regular Credits billing, just settled in on-chain USDC.
  • 0.095215/Credit is the platform's optimal tier (large amount) Credits unit price; the unit price for small top-ups is higher, so X402 automatically gets the optimal unit price.
  • The exact interface (images / videos / music / search / orders) signs the amount due for this transaction; the upto interface (chat) signs the upper limit, settled based on actual usage.
  • The authoritative price is based on the maxAmountRequired returned by 402: exact is the amount due (consistent with the successful response's cost.amount, which has been tested); upto is the upper limit, and the successful response's cost.amount is the actual amount settled based on usage (≤ upper limit).
Document Link
X402 Integration Guide (Overview) X402 Integration Guide
Quick Start X402 Quick Start
exact and upto Billing Plans Billing Plan Description
Networks and Payment Methods Networks and Payment Methods
Order Payment Tutorial Order Payment Tutorial