Avoid token pricing unit mistakes

Read the denominator before multiplying.

Convert rates once

A price per million tokens must be divided by 1,000,000 when multiplying by a raw token count. A rate per thousand tokens uses a different divisor. Keep the unit next to every stored rate and avoid converting a value twice in separate spreadsheet cells.

Separate input and output

With the illustrative prices of $1 per million input tokens and $5 per million output tokens, a request with 2,000 input and 500 output tokens costs $0.0045. Ten thousand identical requests cost $45. The calculation is exact for those assumptions, but real requests are not identical.

Do not treat omitted meters as free

If a provider separately bills cached context, images, audio or tool execution, add those categories to a more complete model. A two-column token worksheet is a useful starting point only when its exclusions are visible. Do not compare providers on one token price while ignoring the workload.

Save a reproducible estimate

Keep the model identifier, date, pricing source, token sample and planned request count with the result. Recheck actual provider pricing before a purchasing decision. The worksheet provides arithmetic, not a recommendation of a model or a prediction of the final invoice.