ChatGPT API Pricing and Integration Costs for UK Businesses (2026)

Why this article exists

The most common question in a first ChatGPT implementation conversation is: "what will this cost?" Most vendors either refuse to answer or give a range so wide it is useless. This article provides specific, tiered cost benchmarks for UK ChatGPT API and Enterprise integrations, based on actual scoping and build work rather than estimates produced for marketing purposes. The figures are in GBP, cover both one-off build costs and ongoing running costs, and explain what drives a project from one tier to the next.

These figures are directional, not fixed. Every project is scoped individually because the variables (integration depth, data complexity, user volumes, governance requirements, regulatory sector) affect cost significantly. The value of this article is to give you a realistic starting point and help you understand which factors will push your project up or down within these ranges.

Tier 1: Simple API integration (from approximately £3,000)

A Tier 1 integration is a single workflow, one data source, and one output channel. The typical Tier 1 project is: a ChatGPT-powered chatbot on a website, a Slack or Teams bot that drafts responses to internal queries, an email triage workflow that classifies and summarises inbound messages, or a document processing tool that extracts structured information from a specific document type. All of these share common characteristics: one well-defined use case, one data input type, one output format, and a relatively simple integration with existing systems.

Build cost: from approximately £3,000. This covers initial scoping and requirements confirmation, prompt engineering for the specific use case, API integration development, basic testing against real inputs, and deployment to the target channel. At the lower end of this range, the project is close to a template integration. At the upper end (approximately £6,000 to £8,000), there is more bespoke prompt work, a more complex data input, or integration with a specific existing system.

Ongoing running costs at Tier 1. OpenAI API usage charges at current GPT-4o rates are approximately £2 per million input tokens and £8 per million output tokens as of mid-2026. For a moderate-volume Tier 1 integration, such as a customer service chatbot handling 500 conversations per month with typical conversation lengths, total API costs are typically in the range of £50 to £200 per month. This scales linearly with usage volume. If your integration handles ten times the volume, expect ten times the cost. Verify current rates at OpenAI's pricing page, as these are adjusted periodically.

What a Tier 1 project includes. One use case, one data source, basic prompt engineering and testing, deployment to one channel (web, Slack, Teams, email), and a handover document explaining how the integration works and how to maintain it. It does not include retrieval-augmented generation over internal documents, user access controls, analytics dashboards, or ongoing prompt refinement.

Tier 2: Mid-complexity integration (£8,000 to £25,000)

A Tier 2 integration typically involves two to four connected workflows, a CRM or other business system connection, document processing with retrieval-augmented generation, or user access controls requiring role-based permissions. The typical Tier 2 project is: a ChatGPT assistant that reads from a CRM to produce account summaries and draft client emails, a document processing pipeline that ingests PDFs and extracts structured data into a spreadsheet or database, or an internal knowledge assistant that reads from SharePoint or Google Drive and answers staff queries with citations.

Build cost: £8,000 to £25,000. The lower end of this range covers two integrated workflows with standard system connections. The upper end covers four workflows, a retrieval-augmented generation implementation over a substantial internal document library, and user access controls aligned to existing organisational roles. Projects at the upper end of Tier 2 are approaching Tier 3 in complexity.

What drives cost within this range. Four factors push a project toward the upper end of the Tier 2 range: the number of distinct workflows being built simultaneously; the number of external systems the integration needs to connect to (each connector adds engineering time); whether retrieval-augmented generation is required and the complexity of the document library it covers; and whether the project requires user access controls beyond a single shared access model.

Ongoing running costs at Tier 2. API costs at Tier 2 are typically £100 to £500 per month for moderate use across multiple workflows, scaling with volume. Projects using retrieval-augmented generation also incur vector database costs (typically £20 to £100 per month at this scale, depending on document volume). Third-party integration platform costs (Make, Zapier, n8n) where used: £20 to £150 per month.

Tier 3: Enterprise multi-system integration (£25,000 to £80,000 or more)

A Tier 3 integration connects ChatGPT across multiple enterprise systems, including ERP, CRM, document management, and compliance infrastructure. It typically includes ChatGPT Enterprise deployment with UK data residency configuration, a formal change management programme, structured staff training across multiple teams, and an ongoing governance framework. The typical Tier 3 project is: a ChatGPT Enterprise deployment for a 200-person professional services firm connecting to Microsoft 365, CRM, and the firm's document management system; or a regulated-sector deployment at a financial services firm with sandboxed environments, SM&CR accountability documentation, and compliance monitoring built into the governance framework.

Build cost: £25,000 to £80,000 or more. The lower end covers a straightforward multi-system ChatGPT Enterprise configuration with a defined change management programme and training. The upper end covers regulated-sector deployments with complex governance requirements, bespoke system integrations, and multi-phase rollout across departments over several months. Projects above £80,000 are not unusual in regulated sectors where the compliance overlay adds substantial scoping, legal review, and assurance work.

What drives cost at Tier 3. Six factors consistently push projects to the upper end of Tier 3: the number of distinct enterprise systems requiring integration; whether a regulated sector compliance overlay is needed (financial services, legal, healthcare); the size of the user base being trained and onboarded; whether the deployment involves ChatGPT Enterprise licence negotiation through a UK reseller; the depth of the change management programme required; and whether the engagement includes an ongoing operational support arrangement after go-live.

ChatGPT Enterprise licence costs. ChatGPT Enterprise is priced per user per month, with the specific rate negotiated per contract and dependent on user volumes. As of mid-2026, indicative pricing is approximately £25 to £35 per user per month for teams above minimum thresholds, negotiated through an authorised UK reseller. PwC is the first UK authorised reseller. At 100 users, the annual licence alone is £30,000 to £42,000, in addition to the integration build cost.

Ongoing running costs at Tier 3. API costs at Tier 3 vary enormously by usage volume and workflow design. A 200-user deployment with high-frequency document processing might run £500 to £2,000 per month in API costs. ChatGPT Enterprise licence costs are separate and fixed by contract. Third-party infrastructure (vector databases, integration platforms, monitoring tools) typically adds £200 to £800 per month at this scale.

Ongoing API costs: how to estimate monthly spend

OpenAI charges for API usage by the token. A token is approximately three-quarters of an English word. The key pricing inputs for a ChatGPT API integration are: the number of requests per month, the average number of input tokens per request (the prompt, context, and any documents provided), and the average number of output tokens per request (the response generated).

A worked example for a Tier 1 chatbot handling 1,000 conversations per month with an average of 500 input tokens and 300 output tokens per conversation: input cost is 1,000 times 500 divided by 1,000,000 times £2, which equals £1.00; output cost is 1,000 times 300 divided by 1,000,000 times £8, which equals £2.40; total monthly API cost is approximately £3.40. This is lower than many businesses expect, and illustrates that API costs at moderate volume are often not the primary cost driver in a ChatGPT implementation. Build cost, change management, and ongoing governance are usually larger.

Costs become material at very high volumes. A business handling 100,000 AI-assisted customer service interactions per month at similar token volumes would spend approximately £340 per month on API costs, still reasonable. The scenarios where API costs become the dominant concern are high-frequency document processing over large documents, where input token counts per request can be 10,000 to 100,000 rather than 500.

What pushes a project into a higher tier

The single most reliable predictor of project cost is the number of distinct systems that need to be connected. Each system connection adds engineering time for integration development, testing, and ongoing maintenance. A one-system integration is Tier 1. A three-system integration is Tier 2. A five-system integration with governance requirements is Tier 3.

The second most reliable predictor is regulatory and compliance requirements. A non-regulated SME deploying ChatGPT for internal drafting work sits at Tier 1 or 2. The same technical project at an FCA-regulated firm, requiring a DPIA, SM&CR accountability documentation, Consumer Duty governance, and IT risk management sign-off, adds weeks of scoping and governance work that push it to Tier 2 or 3.

The third predictor is user volume and change management scope. A tool used by five people needs minimal change management. A tool rolled out to 200 people across five departments over four months requires a structured change management programme, role-specific training materials, adoption measurement, and management communication. This work is real cost and is commonly underestimated in initial budgets.

Why a free scoping consultation matters before committing to a budget

The figures above are directional benchmarks. The actual cost of your project depends on factors that can only be assessed in a scoping conversation: the specific systems you need to connect, the data types involved, the regulatory context, the size of the user base, and the governance requirements your organisation imposes on technology projects.

A scoping conversation identifies which tier your project sits in, what the specific variables are that drive cost within that tier, and whether there are simpler approaches to your use case that achieve the same outcome at lower cost. It also identifies the compliance and governance requirements that need to be in place before build work begins, which affects timeline as well as cost.

For a free initial consultation and a written, itemised proposal specific to your use case, see our ChatGPT implementation service. For a broader view of AI consultancy engagement costs and structures, see our pricing and engagements page.