Spending the Google AI Pro Cloud Credit on Transcription
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A Google AI Pro subscription includes $10 of Google Cloud credit every month. If you do not run anything on Google Cloud, it is easy to end up not knowing what to do with it.
I spend mine on transcription for Ayumi, the voice-journaling app I am building. Recordings go to Gemini 3.8 Flash through the Gemini API, and the bill is paid out of that credit.
Whether the credit covers the Gemini API
My setup uses postpaid billing: Ayumi’s API key belongs to an AI Studio project linked to a regular postpaid Cloud Billing account. In that setup, the credit does apply. In the billing report for that project from July to October 2026, the usage appears under the Gemini API service, and the credit offset ¥2,147 of ¥2,159.
Prepaid billing is less clear, and it matters because the Gemini API billing guide says new users default to the prepaid plan. A June 2026 thread on the Gemini developer forum reports that the AI Pro credit could not be used for an AI Studio project on prepaid billing; Google Support’s reply there said promotional credits cannot fund the prepaid balance. The billing guide, as of October 2026, describes the prepaid plan this way: the minimum purchase is $5, and once you have a positive prepaid balance, eligible Google Cloud credits are consumed before that balance. When the prepaid balance reaches $0, credits stop being consumed and the API keys stop working, even if credit remains. The guide does not say whether the AI Pro credit counts as eligible, and I have not tried the prepaid route myself.
The credit also does not have to be spent in the month it arrives. Each monthly grant is a separate credit valid for one year, and I currently have five grants that are still untouched.
How many hours $10 buys
The figures below come from the token counts I measured in kikitori-bench, my ASR benchmark: 3 hours 5 minutes of unscripted Japanese voice-journal audio, priced at the Gemini API paid-tier list prices as of October 2026.
| Model | Cost per hour of audio | Hours for $10 |
|---|---|---|
| Gemini 3.8 Flash | about $0.21 | about 47 hours |
| Gemini 3.8 Flash (thinking off) | about $0.09 | about 107 hours |
| Gemini 3.5 Transcribe | about $0.30 | about 33 hours |
| Gemini 3.5 Flash-Lite (estimate) | about $0.04 | about 220 hours |
Gemini 3.8 Flash, with thinking left at the API default, is the one I use. In my benchmark it scored highest on my recordings, and roughly 47 hours a month is far more than I dictate into a journal.
Turning thinking off more than doubles the hours. In kikitori-bench, it cut the ASR cost by more than half and lowered the overall score from 76.1% to 71.1%.
Gemini 3.5 Transcribe is the dedicated transcription model. It is the most expensive of the four per hour, and on my audio it scored below Gemini 3.8 Flash.
Flash-Lite is the cheapest option. I have not benchmarked it, so its row is an estimate: the same input token count at Gemini 3.5 Flash-Lite’s rates ($0.30 per million audio input tokens, $2.50 per million output tokens), with the output token count of the thinking-off run. I do not know how accurate it is on my recordings.
Caveats
These numbers come from one speaker’s Japanese dictation. Output token counts depend on the language and on how much the model thinks, so your hours will differ.
The Gemini 3.8 Flash price is a promotional rate that runs through December 31, 2026. From January 1, 2027, input goes from $0.75 to $1.50 per million tokens and output from $3.75 to $7.50, which halves the hours in the first two rows.
If your credit is sitting unused, I hope this gives you one idea for it.