Formulas and sources
Each formula this calculator uses, where it comes from, and what it leaves out. "How it works" shows the same formula with your own numbers.
Cost of a run
Simple and Compare modes
- Total Cost
- the cost of one run
- Number of Images
- the images billed: the images you request, one per prompt, with variations and retries added
- Cost Per Image
- the model’s price for one image at the size shown; for Midjourney, for one prompt
Prices are in US dollars, as each provider’s pricing page states them. A price marked “est.” is an estimate where the provider bills another way: by token, at an approximate price, or, for Midjourney, by subscription GPU time per prompt. This panel carries no prices: the model details under the model picker show the price in use and the date of the last check. Compare mode prices each model at its own price and ranks them by total cost; a custom price applies to the selected model only.
Source: Standard formula; no single publisher. Prices are each provider’s own, such as OpenAI’s per-image table [1] and Google’s per-image equivalents [2].
Images billed
With Variations or Retry rate set
- Effective Images
- the images billed
- Images
- the images you request, one per prompt
- Variations
- how many times each prompt is run
- Retry Rate
- the share of images you regenerate, as a percentage
Every image the model generates is billed, whether or not you keep it.
Source: CalcTrail’s own calculation; no publisher.
Monthly cost
With Runs per month set
- Monthly Cost
- the cost of a month of runs
- Total Cost
- the cost of one run
- Runs per Month
- how often you repeat the run
Source: Standard formula; no single publisher.
Sources
- OpenAI. Image generation, sections "Cost and latency" and "Calculating costs". Undated page, read October 4, 2026.
- Google. Gemini Developer API pricing, the image model rows, the "Equivalent to" per 1K image price. Undated page, read October 4, 2026.
What this calculator does not cover
- Each price is for the one size and quality shown beside the model. Other sizes can cost more or less, and the calculator does not price them.
- For token-billed models the estimate covers the image output only; text and image input tokens are extra.
- Subscriptions, minimum spends, included credits, volume discounts and batch prices are not applied. A custom price takes a contract rate.
- The time to write prompts, review and edit results, and licensing are not included.
- Midjourney has no API. Its figure is CalcTrail’s own estimate from subscription GPU time, for one prompt, which returns several images.
Sources checked on .