Quick answer: buy the hardware only if you will use it more than a few hours a day. A used RTX 3090 at ~$820 takes about 9 months of 24/7 use to beat Vast.ai rental, 26 months at 8 hours a day, and never pays back at 2 hours a day. Light or bursty use is cheaper in the cloud, and that stays true at every card tier below.
Every local LLM builder asks the same question at some point: am I actually saving money, or would cloud GPUs be cheaper? I ran the numbers for every common scenario — casual hobbyist to 24/7 production — and the break-even points are more clear-cut than most people expect.
NVIDIA GeForce RTX 3090
24GB GDDR6XA used RTX 3090 at ~$820 breaks even in about 3 months of 24/7 use against RunPod 4090 rental, or about 9 against cheaper Vast.ai 3090 rental at moderate usage.
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Cloud GPU pricing in 2026
Current spot and on-demand rates for LLM inference workloads:
| Provider | GPU | $/hour | 4 hrs/day monthly | 8 hrs/day monthly | 24/7 monthly |
|---|---|---|---|---|---|
| RunPod | RTX 4090 | $0.44 | $53 | $106 | $317 |
| RunPod | A100 80GB | $1.39 | $167 | $334 | $1,001 |
| RunPod | H100 | $2.49 | $299 | $598 | $1,793 |
| Vast.ai | RTX 4090 | $0.35 | $42 | $84 | $252 |
| Vast.ai | RTX 3090 | $0.18 | $22 | $43 | $130 |
| Lambda | A100 80GB | $1.29 | $155 | $310 | $929 |
Vast.ai prices fluctuate — it’s a marketplace. The numbers above reflect April 2026 averages. RunPod is more predictable. For a deeper feature comparison, see RunPod vs Vast.ai for LLM.
Try RunPod Cloud GPU→ Try Vast.ai Cloud GPU→Self-hosted GPU costs
Hardware purchase is the upfront cost. Electricity is the ongoing cost. Everything else — internet, your time — is negligible for most hobbyists.
| GPU | Purchase price | TDP | Electricity/mo (8 hrs/day)* | Electricity/mo (24/7)* |
|---|---|---|---|---|
| RTX 3090 (used) | ~$820 | 350W | $18 | $53 |
| RTX 4090 | ~$2,200 | 450W | $23 | $69 |
| RTX 5090 | ~$4,900 | 575W | $29 | $88 |
Assumes $0.18/kWh, the EIA US residential average for June 2026, full rated TDP and an 85%-efficient PSU. Adjust for your area — the EU household average is about $0.31/kWh and Germany about $0.42.
The electricity cost matters more than people think over 12+ months. A 4090 running 24/7 adds ~$550/year to your power bill.
Break-even analysis
This is the core question: how many months until your hardware investment pays for itself compared to renting the equivalent cloud GPU?
RTX 3090 (used at $820) vs Vast.ai RTX 3090 ($0.18/hr)
| Usage | Cloud monthly cost | Self-hosted monthly cost | Break-even |
|---|---|---|---|
| 2 hrs/day | $11 | $6 (electricity) | Never — cloud is cheaper |
| 4 hrs/day | $22 | $8 | ~59 months |
| 8 hrs/day | $43 | $12 | ~26 months |
| 24/7 | $130 | $36 | ~9 months |
Break-even is the purchase price divided by what you save each month, so it moved with the card: these were 38, 19 and 6 months when a used 3090 cost $600 earlier in 2026.
RTX 4090 ($2,200) vs Vast.ai RTX 4090 ($0.35/hr)
| Usage | Cloud monthly cost | Self-hosted monthly cost | Break-even |
|---|---|---|---|
| 2 hrs/day | $21 | $7 (electricity) | ~157 months |
| 4 hrs/day | $42 | $10 | ~69 months |
| 8 hrs/day | $84 | $15 | ~32 months |
| 24/7 | $252 | $46 | ~11 months |
RTX 3090 (used at $820) vs RunPod RTX 4090 ($0.34/hr)
This is the comparison that makes self-hosting look strongest — a cheap used card vs a premium cloud provider:
| Usage | Cloud monthly cost | Self-hosted monthly cost | Break-even |
|---|---|---|---|
| 4 hrs/day | $53 | $8 | ~18 months |
| 8 hrs/day | $106 | $12 | ~9 months |
| 24/7 | $317 | $36 | ~3 months |
The used RTX 3090 at $820 is still the fastest break-even card in the entire GPU market. At 8 hours/day of usage, it pays for itself in roughly nine months against any cloud provider.
Check NVIDIA GeForce RTX 4090 on Amazon→Buy on Shopee SG→When cloud still wins
Self-hosting doesn’t always make sense. Cloud GPUs are the better choice when:
- You need H100/A100 compute. Buying an H100 costs $25,000+. Renting one at $1.99/hr on RunPod’s community tier, or $2.89 secure, is the only realistic option for most people running 70B+ models at full precision.
- Usage is sporadic. If you run LLMs a few hours per week for experimentation, even Vast.ai’s cheapest rates beat the amortized cost of hardware sitting idle.
- You need to scale up and down. Training a model for 48 hours, then not touching it for a month? Cloud handles that pattern; a local GPU just collects dust.
- You’re evaluating before committing. Spend $20 on cloud time to test whether local LLM actually fits your workflow before spending $820-2,200.
For a broader comparison of the cloud vs local tradeoffs beyond just cost, see Cloud vs Local GPU for LLM.
When self-hosting wins
Buy your own GPU when:
- You use it 4+ hours daily, consistently. The break-even math is undeniable at moderate usage.
- Privacy matters. Your data never leaves your machine. No cloud provider sees your prompts or outputs.
- You want zero latency overhead. No SSH, no network, no cold starts. Run ollama and start generating immediately.
- You’re running 24/7 services. A local LLM API for your team, a RAG pipeline, or a coding assistant that’s always on. For dedicated always-on inference boxes, our best GPU for an LLM server guide covers the throughput and reliability picks.
The rule of thumb
If you consistently use a GPU 8 or more hours per day, self-host. Below about 2 hours per day, rent. In between, the answer depends on which cloud you are comparing against more than on which card you buy.
That middle band is wider than it used to be. A used RTX 3090 at $820 pays back in about 9 months at 8 hours a day against RunPod, but about 26 months against Vast.ai, whose 3090 rate is roughly half of RunPod’s 4090 rate. At 4 hours a day the same card takes 18 months against RunPod and nearly five years against Vast.ai — long enough that the card is obsolete first. The 2026 price rises pushed every one of these thresholds out; the old advice of “more than 4 hours a day, buy” was written when a used 3090 cost $600.
For most LLM hobbyists who run models daily for development, coding assistance, or research, a used RTX 3090 is the most cost-effective entry point. For those who need occasional access to larger models, cloud providers fill the gap — and if that occasional need is training rather than inference, renting a GPU for fine-tuning usually beats buying by an order of magnitude.
NVIDIA GeForce RTX 4090
24GB GDDR6XRTX 4090 at ~$2,200 breaks even vs cloud in ~8 months at 24/7 usage. 24GB VRAM handles 34B models with headroom.
Affiliate links — we may earn a commission at no extra cost to you. Amazon ships globally; Shopee SG covers Singapore & ASEAN.
Frequently asked questions
How long does it take for a local GPU to pay for itself vs cloud?
At 8 hours/day usage, a used RTX 3090 ($820) breaks even in about 9 months against RunPod 4090 rental, or about 26 months against the much cheaper Vast.ai 3090 rate. An RTX 4090 ($2,200) breaks even in about 11 months at 24/7 usage against Vast.ai. Which provider you are comparing against changes the answer more than the card does.
Is cloud GPU cheaper for casual LLM use?
Yes. If you use LLMs less than 2 hours per day, cloud GPU rental (especially Vast.ai at $0.18/hr for a 3090) is cheaper than owning hardware.
What are the hidden costs of self-hosting an LLM GPU?
Electricity is the main ongoing cost ($12-46/month depending on GPU and usage). Other costs include PSU upgrades for power-hungry cards, cooling, and your time for setup and maintenance.