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Cheapest GPU for ComfyUI & Flux in 2026
ComfyUI and Flux are the tools every AI image creator runs in 2026 — and both live or die on one number: VRAM. Pick a card with too little and you wait forever or crash. Pick a card with too much and you pay for memory you never use. This guide picks the cheapest card for each job, with real hourly prices.
Prices checked 15 November 2026 (RunPod Community Cloud, October 2026 checks; prices move with demand — always check the live price before you deploy).
How much VRAM do you actually need?
| Job | VRAM needed | Cheapest card that works |
|---|---|---|
| Flux, 512×512 | 12 GB | RTX A4000 (~$0.20/h) |
| Flux, 1024×1024 | 16–24 GB | RTX A5000 24 GB (~$0.16/h) |
| Flux, full quality + upscaling | 24 GB | RTX 3090 / RTX 4090 (~$0.22–$0.34/h) |
| ComfyUI video (Wan, LTX) | 24–32 GB | RTX 4090 / RTX 5090 (~$0.34–$0.99/h) |
| LoRA training | 24 GB | RTX 4090 (~$0.34/h) |
| Large video, long clips | 48 GB | L40S (~$0.99/h) |
The cheapest picks, by job
Cheapest overall: RTX A5000 — ~$0.16/h
24 GB of VRAM for sixteen cents an hour. It is slower than a 4090, but for Flux at 1024×1024 it is the best value on the board. If you generate a few images at a time and you are not in a hurry, start here.
Best value: RTX 4090 — ~$0.34/h
The default answer for a reason. 24 GB, fast, available everywhere, and every ComfyUI template is tested on it. One afternoon of generation (4 hours) costs about $1.36. If you only rent one card, rent this one.
For video: RTX 5090 or L40S
Video models eat VRAM. The RTX 5090 (32 GB, ~$0.99/h) handles most video work; the L40S (48 GB, ~$0.99/h) handles longer clips. Do not try heavy video on a 12 GB card — it will offload to system RAM and take ten times longer.
How a GPU renders your image — the 30-second version
A GPU is thousands of small cores that do the same maths at once. When you run Flux, the model starts from noise and refines it step by step — usually 20 to 30 steps — and each step runs across all those cores in parallel. More VRAM means the whole model and your image fit in fast memory at once; less VRAM means parts get shuffled to slow system RAM, and every shuffle costs time. That is the whole reason VRAM, not raw speed, decides which card you need.
Renting a GPU for ComfyUI, step by step
- Sign up on RunPod with Google SSO (the referral bonus only registers with Google sign-in).
- Load $10 of credit — the minimum top-up.
- Pick the ComfyUI template and your card (RTX 4090 if unsure).
- Open the web UI from the Pod page and load your workflow.
- Stop the Pod when you are done — and delete the volume, or storage keeps billing.
The mistakes that double your bill
- Renting a card with too little VRAM. Offloading to RAM makes a $0.16/h card slower than a $0.34/h card. Pay for the VRAM you need.
- Leaving a Pod running overnight. An RTX 4090 at $0.34/h is $8.16 a day. Stop it when you stop working.
- Forgetting storage. A stopped Pod still bills ~$0.20/GB/month for its disk. Delete the volume.
- Picking the fastest card for a small job. An H100 at $2.69/h does not make a single Flux image 8× faster than a 4090. Match the card to the job.
Kavvo verdict — tested 15 November 2026
Start with an RTX 4090 on RunPod Community Cloud (~$0.34/h). It is the cheapest card that does every ComfyUI and Flux job well. Drop to an RTX A5000 (~$0.16/h) if you generate slowly and want the lowest bill; step up to an L40S only for heavy video. Check the monthly maths first in the GPU cost calculator, and compare providers in Best GPU Cloud 2026.
Frequently asked questions
How much VRAM do I need for ComfyUI and Flux?
12 GB is the minimum for Flux at low resolution, 16 GB is comfortable, and 24 GB (RTX 4090) is the sweet spot — it runs Flux at full quality without offloading, and it handles video models too. Below 12 GB you will spend more time waiting than generating.
What is the cheapest GPU for Flux?
On RunPod Community Cloud, an RTX A5000 (24 GB) from ~$0.16/h or an RTX 3090 (24 GB) from ~$0.22/h are the cheapest cards with enough VRAM for Flux. The RTX 4090 (~$0.34/h) is faster and worth it if you generate a lot.
Is an RTX 4090 good for ComfyUI?
Yes — it is the best value card for ComfyUI in 2026. 24 GB of VRAM, fast generation, and cheap hourly rental. For heavier video models, step up to an L40S (48 GB) or an A100 (80 GB).