Do I need to train my own AI model?

Almost never. Comparable apps use a hosted model through an API and add their own instructions, data and interface. Training a model from scratch is a different order of cost and is not included here.

What makes a custom AI chat app worth building?

Your own data, workflows and audience. A chat assistant that answers from your documents, works inside your product or follows your rules does things a general chatbot can't.

Is this what ChatGPT spent to build its app?

No. It is Eltherion's estimate for building a comparable first version today. It says nothing about what ChatGPT spent, and Eltherion is not affiliated with ChatGPT. A product at that company's scale has years of work and teams behind it that no MVP includes.

How can I lower the cost?

Launch with fewer integrations, one market and one platform, and leave the full-platform features until users ask for them. The adjustable calculator shows how each choice moves the range.

Learning and AI apps

How much does it cost to build an app like ChatGPT?

By Nick McCandless, founder of EltherionUpdated October 30, 2026

Short answer

Eltherion prices an MVP of an app like ChatGPT, an AI chat assistant app, at $24k to $80k. A full platform with the features listed below runs $49k to $156k. These are Eltherion's own estimate ranges for building a comparable product, not what ChatGPT spent; your fixed price comes after a free scoping call, and small, tightly scoped work starts as low as $1,000.

Adjust this estimate in the calculator Get a fixed quote

An app like ChatGPT gives people a chat interface to an AI model, with conversation history, file uploads and answers that stream as they are written. A comparable product is built on a hosted AI model API; this estimate does not include training your own model.

What an MVP of an app like ChatGPT costs, feature by feature

The first version below is the smallest product people could actually use. Core features are covered by the base price for an AI system; each outside service the app connects to, and each add-on, adds its own line.

Eltherion estimate for an app like ChatGPT, MVP (updated October 30, 2026)
Line item	What it covers	Estimate
Core AI system (MVP)	Chat interface, Accounts and usage limits, Prompt and safety layer, Admin dashboard	$20k to $70k
Hosted AI model API	Answers from a model provider, billed per use	$2k to $5k
Subscription billing	Free and paid plans	$2k to $5k
Total		$24k to $80k

Chat interface: Streaming answers, conversation history and editing.
Accounts and usage limits: Sign in and fair-use limits per plan.
Prompt and safety layer: System instructions, content filters and logging.
Admin dashboard: Users, usage and costs.

What drives the cost of an app like ChatGPT

Model usage is a monthly cost that grows with every message, so usage limits matter from day one.
Answering from your own documents (retrieval) is a project of its own.
Safety, logging and abuse controls are part of the core.

Full platform: $49k to $156k

The full-platform tier prices the same app at full-platform scope ($36k to $126k for the core) plus these additions:

Document search: Answer from uploaded files and your own knowledge base ($2k to $5k).
Voice input and output: Speech through a speech service ($2k to $5k).
Single sign-on: Company login for business plans ($5k to $10k).
Team workspaces and sharing: Shared chats and admin controls (part of the full-platform core).

Most products should not build this tier up front. Ship the MVP, see what users actually do, and add the pieces that earn their place. Open the full-platform estimate in the calculator.

Running costs after launch

Maintenance and small improvements: $4k to $14k a year for the MVP (18% of the build, a planning assumption).
Hosting: about $9k a year (a planning estimate; heavy usage costs more).
Three-year total for the MVP, build included: $63k to $149k.
Card payments: Stripe's standard US rate is 2.9% + 30¢ per successful domestic card transaction (checked October 30, 2026); other providers price differently.

Each integration also has its provider's own usage fees (maps, messaging, video, AI models), which depend on how much the app is used.

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Frequently asked questions

How much does it cost to build an app like ChatGPT?: Eltherion prices an MVP of an app like ChatGPT, an AI chat assistant app, at $24k to $80k, and a full platform at $49k to $156k. These are Eltherion's estimate ranges from its published pricing model; your fixed price comes after a free scoping call. Small, tightly scoped work starts as low as $1,000.
Do I need to train my own AI model?: Almost never. Comparable apps use a hosted model through an API and add their own instructions, data and interface. Training a model from scratch is a different order of cost and is not included here.
What makes a custom AI chat app worth building?: Your own data, workflows and audience. A chat assistant that answers from your documents, works inside your product or follows your rules does things a general chatbot can't.
Is this what ChatGPT spent to build its app?: No. It is Eltherion's estimate for building a comparable first version today. It says nothing about what ChatGPT spent, and Eltherion is not affiliated with ChatGPT. A product at that company's scale has years of work and teams behind it that no MVP includes.
How can I lower the cost?: Launch with fewer integrations, one market and one platform, and leave the full-platform features until users ask for them. The adjustable calculator shows how each choice moves the range.

How we priced this

Every number on this page comes from Eltherion's software development cost calculator: a base range for the product type, multiplied by scope, plus a fixed range for each integration and add-on. The method is published on the cost methodology page. The feature list describes a typical comparable product; Eltherion is not affiliated with ChatGPT.