Image Generation GPU Economics: Flux & SDXL Cost (2026)
Cheapest verified GPUs for diffusion workloads: Flux.1 [dev] sizing from the model registry against observed hourly rental rates.
The fast answer
Cheapest verified GPU: GeForce RTX 4090 at $0.34/hr on-demand (Vast.ai) among 4 candidate GPUs. Lowest on-demand hourly row for this GPU's providers.json key; refreshed daily.Observed On-Demand
VRAM needed: FLUX.1 [dev] at INT4 needs 16.4 GB full-stack (weights 6 GB + KV-cache + overhead) at 128,000 tokens.
Cost driver: Batch diffusion amortizes weights-load: the card that fits the checkpoint with headroom for batch > 1 delivers the best images/hour per dollar.
Candidate GPUs for Image Generation
Fit = full-stack VRAM total for FLUX.1 [dev] (INT4/FP16 at model context) ≤ GPU VRAM. Rates are observed rows from data/providers.json, refreshed daily.
| GPU | VRAM | Bandwidth | INT4 fit | FP16 fit | On-demand | Spot |
|---|---|---|---|---|---|---|
| GeForce RTX 4090 | 24 GB | 1.0 TB/s | ✓ fits | OOM | $0.34/hr | $0.34/hr |
| L40S | 48 GB | 864 GB/s | ✓ fits | ✓ fits | $0.69/hr | $0.69/hr |
| A100 80GB SXM4 | 80 GB | 2.0 TB/s | ✓ fits | ✓ fits | $1.59/hr | $1.59/hr |
| H100 SXM5 | 80 GB | 3.35 TB/s | ✓ fits | ✓ fits | $1.89/hr | $1.89/hr |
Reference models for this workload
Methodology & provenance
VRAM fit uses the registry entry for FLUX.1 [dev] (weights + activation budget from the same param/quantization model as LLMs). Diffusion decode is compute-heavy rather than decode-bound, so value per dollar favors high-tensor-throughput consumer and pro cards — rates shown are observed provider rows, and images/hour is left to measurement rather than asserted.
Next steps