Whisper API bills by audio duration, and accounts are prepaid; when the balance runs out, requests fail immediately. For teams doing meeting transcription, subtitles, and customer service quality checks, topping up is not a one-time action but a long-running chain that needs reconciliation: how the money leaves, how credit arrives, who knows when the balance is nearly gone, and whether the invoice satisfies finance.

This article compares official top-ups with domestic gateway top-ups. Anything related to price points to the on-site pricing page rather than hard-coded numbers.

Note: OpenAI and Whisper are trademarks of their respective owners. This article covers technical integration and purchasing processes only and does not represent any official endorsement. API, billing, and invoice policies are subject to the official pages and the on-site pricing page.

1. Understand how Whisper API charges first

Whisper is OpenAI's speech recognition model. The hosted API accepts audio files through /v1/audio/transcriptions and usually bills by audio minute. Specific unit prices, available models, and billing rules are subject to the official documentation and the on-site pricing page.

Unlike text models billed by token, audio transcription has three characteristics:

  • Cost follows audio duration and has little to do with file size;
  • A single request may run for tens of seconds to several minutes, and failed retries also consume credit;
  • Batch jobs often run at night, when nobody is at the computer as the balance runs low.

So the correct budget calculation is: the actual audio minutes from the last week multiplied by the unit price, plus a 20–30% allowance for retries and peaks. Do not estimate with an average cost per order; the sample is too small and the error too large.

2. Two top-up paths: official and gateway

Path A: an official OpenAI account

Bind a payment method on the OpenAI platform, purchase prepaid credit, and enable auto-recharge if needed. The advantages are a direct billing entity and immediate access to models and APIs; the cost is that you need a usable overseas payment method and stable access to the dashboard, and you handle exchange rates, taxes, and invoices yourself. It suits teams with an overseas entity or overseas payment channel.

Path B: a domestic AI gateway

Register with the ZSQH AI Gateway, top up the account balance in RMB, and use the same key to call the audio API. Gateways usually provide an OpenAI-compatible entry point, with text, audio, and embedding sharing one bill. It suits teams that pay domestically, need RMB invoices, and connect to multiple model providers at the same time.

Dimension Official OpenAI Domestic gateway
Settlement currency USD RMB
Payment method Overseas card or corporate cross-border payment Online payment, corporate bank transfer
Invoice Handled by you Issued by the platform per order
Credit arrival Usually immediate, depending on channel Online payment is fast; bank transfer needs manual confirmation
Balance management Official dashboard Gateway dashboard, unified across models
Best for Overseas entities, single model Domestic teams, multiple models

The two paths do not replace each other. Before choosing, ask three questions: does the payment method work, can the invoice satisfy finance, and who is responsible when something goes wrong. If any answer is unclear, it is worth comparing again.

3. Exchange rates, fees, and credited amount

Gateways settle in RMB and must convert RMB into USD to pay upstream. There are usually three layers of cost:

  1. The settlement rate: whether conversion uses a live rate, an end-of-day rate, or a fixed rate;
  2. The payment channel fee: online payment, corporate transfer, and cross-border remittance have different rates;
  3. The service fee: whether the platform adds a layer on top of the exchange rate.

The reconciliation formula is:

Credited amount (USD) = RMB paid ÷ settlement rate − channel fee − service fee

Before topping up, confirm three things on the page: which line states the exchange rate, whether fees are listed separately, and whether the credited amount is calculated using the formula above. If the page only says "pay X, get Y" without explaining the conversion, ask for a written explanation before paying.

Also distinguish cash balance from promotional balance. Promotional credit usually cannot be refunded or invoiced, may have an expiry date, and may be deducted in a different order. Keep the two types of balance in separate accounts in enterprise budgets so the month-end reconciliation works.

4. Verifying credit and balance alerts

The first thing to do after credit arrives is not to run a batch job, but to check three numbers: the order amount, the account balance, and the transaction record. Continue only when all three agree.

Set balance alerts in this order:

  1. Set a low-balance alert threshold for the account in the gateway dashboard;
  2. Create a separate key for each project and set a spending cap;
  3. Turn on usage logs and confirm you can filter by key, model, and day;
  4. Run a short audio clip through a real charge and confirm the balance changes;
  5. Put a fixed weekly usage review on the operations calendar.

Auto-recharge reduces interruptions, but configure the charge cap and the notification recipient. Night batch jobs especially need headroom: if the balance runs out halfway through, the transcription fees already incurred are spent but the results are lost, which is the most painful kind of waste.

5. Refund rules: read the terms before topping up

  • Whether unused cash balance is refundable, how much is refunded, and where it is returned are subject to the platform terms;
  • Consumed credit, promotional credit, and campaign credit usually cannot be refunded;
  • Official prepaid credit is generally not refunded for the unused portion either; refer to official policy;
  • Refund timing follows the payment channel and may cross business days.

Testing the chain with a small amount before a large top-up is the cheapest form of risk control. For individual testing, top up only enough to finish one project; do not leave a balance idle for long periods.

6. Invoices and enterprise procurement

The most common problem in enterprise procurement is not payment but inconsistent expectations. Before paying, put the following into the purchase order:

  • Invoice type: standard VAT invoice or special VAT invoice;
  • Billing entity: company name, tax ID, address and phone, bank and account number;
  • Invoice amount: based on the amount paid or the credited amount;
  • Invoice timing: how long after payment, whether supplementary invoices are supported, and how cross-month cases are handled;
  • Supporting documents: order number, contract, payment receipt, and statement of account.

When using a corporate process, confirm that the contract entity and the receiving account match before arranging payment. Procurement, finance, and engineering should clearly divide who requests the invoice, who stores the documents, and who reconciles the account. For projects involving data security, also confirm the provider's log retention, deletion mechanism, and data processing terms before deciding which audio may be uploaded.

7. The first transcription after topping up

After a small amount of credit arrives, verify the chain with a ten-second public audio clip:

export WHISPER_API_KEY="sk-your-key"

curl "https://ai.zhongshangqihang.com/v1/audio/transcriptions" \
  -H "Authorization: Bearer $WHISPER_API_KEY" \
  -F "file=@sample.mp3" \
  -F "model=whisper-1" \
  -F "language=zh" \
  -F "response_format=json"

A 200 response with text means the key, balance, and model all work. If it fails, check in order: whether the balance arrived, whether the key has a spending cap, whether the audio model is enabled, whether the request is rate-limited, and whether the base URL and path are correct.

Frequently asked questions

Is topping up the same as a ChatGPT subscription?

No. The subscription is for individual use of the product, while API top-ups are for programmatic calls. The two credit pools are separate and cannot offset each other.

After paying in RMB, will the bill show USD or RMB?

It depends on the provider. Gateways usually give RMB orders and RMB invoices, while the usage page may also show USD consumption for reconciliation with upstream providers.

What happens to a running batch job when the balance runs out?

Subsequent requests fail, but transcriptions already completed are still billed. Split batch jobs into small batches and check the balance and failure list after each batch.

Can I request an invoice immediately after topping up?

Most platforms allow a request after payment, but invoice timing, type, and required materials are subject to platform policy. Enterprises should confirm before paying.

Can unused balance be refunded?

Check the terms. Cash balance, promotional balance, and consumed credit follow different rules; ask before topping up rather than after you stop using the service.

Next steps

If you need RMB top-ups, a unified bill, and RMB invoices while calling text, audio, and embedding APIs, you can register for the ZSQH AI Gateway, top up a small amount, run one transcription, and then split keys by project. Specific prices and billing rules are subject to model pricing.

Related reading: