The useful number for planning is the usage basis applied to your account. A file's download size tells you how much media was delivered, but it may not tell you how much volume is billable.
Check your dashboard and accepted plan terms for your rate, allowance and billing basis. This guide explains how to read those figures and test a workload before sending it at volume.
Delivered volume and billable volume
Delivered volume is the size of the files produced by completed jobs. It helps you plan storage and the amount of media your downstream tools will receive.
Billable volume is the volume used by the applicable billing rules. When an organization's 720p billing floor is enabled, an eligible job can count more than the file's delivered size. An account without that floor can use a different basis. Do not assume that a figure labelled usage, quota or delivered volume is automatically the invoice basis.
The billing documentation describes the rules in more detail. The settings and terms for your account determine which of those rules apply to your work.
Why a clip can count more than its file size
For an eligible job with the floor enabled, the base calculation is the largest of the delivered size, the full source's 720p reference and a 1 MB minimum. The reference comes from available source information or an estimate when source size is unavailable.
For example, suppose an eligible source has a 500 MB reference and your clip delivers a 4 MB file. The floor-based volume is 500 MB. That is an example of volume, not a price quotation: your applicable rate determines the charge.
Each job is measured separately. Five clips from that source can count the reference five times. Audio extraction and lower-resolution outputs can also produce files smaller than their billable reference. Changing the output to a smaller file is therefore not enough to establish a lower bill.
A complete file actually delivered at 720p or above uses its delivered size, subject to the 1 MB minimum, when the reference would otherwise be higher. That correction does not apply to clips. Spotify and live-capture modes are exempt from this floor; other sources do not gain an exemption simply because the output is audio.
Run a representative cost check
Choose a small sample that includes the sources, durations and output modes you expect to use. Include clips and audio separately if they are part of your application.
For each completed job, retain the job ID, delivered size and the usage shown for it. Compare the account totals over the same period. Usage updates during finalization and aggregation can take time, so allow for that delay before treating a difference as an accounting error.
If you cannot identify the basis applied, send support the job IDs and time period. You do not need to send your API key or storage credentials. Resolve the difference before extrapolating the sample to a larger workload.
Allowances, invoices and budgets
A trial quota, a pay-as-you-go allowance and included subscription volume are different account states. Read the onboarding and billing screens for the one you have. Eligible paid usage can continue after a PAYG allowance runs out; reaching an allowance is not necessarily a spending stop.
PAYG uses decimal units: 1 GB is 1,000,000,000 bytes and 1 MB is 1,000,000 bytes. Invoice usage is rounded to MB. Settlement timing depends on the account's cadence and charge settings, so there is no universal minimum invoice threshold to infer from this article.
Where available, volume alerts help you notice consumption and a monetary budget can notify you or pause eligible API keys at a cap. A budget check is periodic. Work already in progress and propagation delays can cause the final usage to exceed the cap. Keep that margin in your own workload plan.
Include the rest of your workflow
Your storage provider and downstream tools may charge for storage, reads, transfers, transcription or other processing. Those are separate from Tornado usage. Direct delivery can simplify the route into your storage, but it does not remove your provider's pricing rules.
Open the dashboard to inspect Usage and Billing, then use the first-workflow guide to test the request you intend to scale.