Cost Explanation

Overview

At Learn by Bits, we strive to keep your learning experience affordable and transparent. Your costs are based on the resources you use—AI processing, database operations, storage, and speech-to-text services—plus a service fee to support our platform. This page breaks down how these costs are calculated, what you’re charged, and why.

As a developer, I hate subscriptions so I decided to make Learn by Bits pay-as-you-go. The close monitoring of our costs allows us to charge you only for what you use, and keep the prices as low as possible. It is possible that this method is not sustainable and we will need to switch to subscription, but I hope that won't be necessary.

Costs are deducted from your account balance in real-time. If your balance drops below $2.00 and auto-refill is enabled, we’ll charge your Stripe payment method $9.99 to keep you going. You can manage your balance and payment methods in your account settings.

How Costs Are Calculated

We use a pay-as-you-go model. Each action (e.g., uploading a file, answering a question) incurs a small cost based on the underlying resources. Here’s how each component works:

AI Processing

Our AI, powered by models like Gemini 2.0 Flash, processes your uploads, generates questions, evaluates answers, and provides feedback. Costs are based on token usage:

  • Input Tokens: what you send to the AI. Currently priced at $1/1,000,000 input tokens
  • Output Tokens: what the AI sends back. currently priced at $4/1,000,000 output tokens
  • Service Fee: We add a service fee onto each action.

Example: Uploading a 100-page PDF might use 300,000 input tokens. Iteratively, the AI will run many times to break down the PDF into bits. This may result in a charge of around $2.50 for the iterative calls (~10 iterations with full context or 50 with partial context). If the content is more dense and more iterations are necessary, the cost will increase.

Database Operations

Every interaction with our database (e.g., saving bits, logging tests) has a tiny cost based on rows read or written.

  • Service Fee: Markup for fees applies

Example: Studying a bit might read 10 rows (user data, bit stats). Charged cost = $0.0000325 (negligible, but adds up over many actions).

Storage

Uploading files (PDFs, audio) incurs storage transfer costs:

  • Transfer Cost: Based on an egress rate.

Example: A 10MB (0.01GB) PDF upload may cost $0.009.

Speech-to-Text

Using speech mode leverages whisper for transcription. This can add up faster than other actions, but we strive to keep it as cheap as possible.

  • Cost: $0.048 per minute (estimated from audio size).
    • paper-thin

Example: A 30-second answer (0.5 minutes) costs 0.5 * $0.048 = $0.024 charged.

Typical Costs

Here are some estimated costs for common actions:

  • Uploading a PDF: ~$2.50 per 100 pages (AI processing dominates).
  • Answering with Speech: ~$0.005 per answer (short answers are cheap).
  • Studying a Concept: ~$0.001 per question (database and AI costs).
  • Deleting a Compendium: ~$0.01 (minimal database writes).

These are estimates; actual costs vary based on usage specifics (e.g., file size, answer length). Check your cost logs for exact details.

Why the Service Fee?

The service fee ensures we can maintain and improve Learn by Bits. It covers:

  • Some of the infrastructure that is difficult to pass through in a more transparent way such as servers that handle multiple users at once.
  • Maintenance, programming
  • A profit margin to sustain the platform.

We keep the margin on speech-to-text thinner than other costs because its base cost is higher, balancing affordability with sustainability.

FAQ

How do I see my costs?

Visit your account page to view a breakdown of your cost logs by action type.

What happens if my balance runs low?

If your balance drops below $2.00 and auto-refill is on, we’ll add $9.99 via Stripe. Toggle this in your account settings.

Why are some actions more expensive?

Actions like uploading large files use more AI resources (e.g., breaking down 100 pages into bits), while simple actions like studying a bit are cheaper.

Can I avoid costs?

Costs are tied to usage. Uploading less, using text mode instead of speech, or studying fewer bits reduces expenses.