LLM Chatbot Hosting: Cost at 5M Messages/Month
What does it cost to run llm chatbot hosting at 5M messages/month? Self-hosted dedicated GPU vs API provider pricing.
The Numbers at 5 Million Messages
| Provider | Monthly Cost | Pricing Model | vs GigaGPU |
|---|---|---|---|
| GigaGPU (2x RTX 5090) | £358/mo | Fixed | — |
| OpenAI GPT-4o-mini | £4200/mo | Per-messages | 91% cheaper with GigaGPU |
| Anthropic Claude Haiku | £3700/mo | Per-messages | 90% cheaper with GigaGPU |
| Together.ai LLaMA 3 8B | £1750/mo | Per-messages | 80% cheaper with GigaGPU |
£46,104 Per Year: That Is What You Save
Five million messages per month is enterprise production volume. At this scale, OpenAI would invoice you £4,200 every month. A dual RTX 5090 setup on GigaGPU costs £358/month — a 91% reduction. The annual savings of £46,104 compared to OpenAI is not marginal; it is transformative for your unit economics.
Even the cheapest API alternative, Together.ai at £1,750/month, costs nearly five times more than dedicated hardware. And unlike API providers, your GigaGPU bill does not budge if you hit 6M or 7M messages in a peak month.
At 5M messages, every day you delay migrating to self-hosted costs roughly £128 in unnecessary API spend. The migration typically takes a single afternoon.
At This Volume, There Is No Debate
- Cost per message: £0.0000716 on GigaGPU versus £0.00084 on OpenAI. You pay 11.7x less per interaction.
- Capacity insurance: A dual-GPU setup gives you redundancy. One node can handle maintenance while the other serves traffic.
- Data sovereignty: 5M messages per month is a serious dataset. Keeping it on your infrastructure means you own it entirely — no third-party training on your users’ conversations.
- Custom model advantage: With this message volume, fine-tuning on your specific domain yields measurable quality improvements that no general-purpose API can match.
The Only Counter-Arguments
- Burst beyond capacity: If you see 20M-message months occasionally, you might supplement dedicated hardware with API overflow for spikes.
- Regulatory mandates: Some sectors require specific providers. Verify compliance before migrating.
- Frontier model lock-in: If your product specifically markets GPT-4o by name, switching to an open-source model has product implications beyond cost.
Why Dual RTX 5090s
At 5M messages/month (roughly 167K/day), you need sustained high-throughput inference across two GPUs. The 2x RTX 5090 setup at £358/month provides 64 GB total VRAM, handles 7B-13B models with aggressive batching, and delivers 20-30% headroom above baseline demand. GigaGPU servers ship production-ready with CUDA, Docker, and popular inference frameworks.
Stop Burning £4,200/month on APIs
Dedicated dual-GPU hosting for 5M messages at £358/month. That is 91% cheaper than OpenAI with zero per-message charges.
