Prompt
How do I estimate cost per training run on different GPU clouds?
Latest observation
A good way to estimate cost per training run is to break it into:
Cost = GPU hourly price × number of GPUs × training time (hours) + storage/network/overhead
Here’s a practical approach.
1) Estimate how long the run will take
Start from a benchmark or a smaller pilot run.
Track:
- steps per second or tokens per second
- total training steps or total tokens
- expected slowdowns from:
- distributed training overhead
- checkpointing
- data loading
- validation / eval
- spot interruptions / retries
Formula:
- Training time (hours) = total work / throughput
- Example:
- 1B tokens total
- throughput = 2,000 tokens/sec
- time = 1,000,000,000 / 2,000 = 500,000 sec ≈ 139 hours
2) Get the effective GPU rate
For each cloud/provider, use the all-in hourly cost per GPU:
- on-demand price
- reserved/committed use discounts
- spot/preemptible discount
- cluster management fees if any
Then compute:
- GPU cost = hourly rate × GPU count × hours
Example:
- 8 GPUs
- $2.50/GPU/hr
- 139 hours
- cost = 8 × 2.50 × 139 = $2,780
3) Add non-GPU costs
Common extras:
- CPU/RAM instances for input pipeline, parameter server, orchestration
- storage for checkpoints and datasets
- object storage requests
- network egress if moving data out of cloud
- managed service fees
- idle time while waiting for nodes, scaling, or failure recovery
Rule of thumb:
- For many training jobs, non-GPU costs are small relative to GPUs, but they can matter for long runs with lots of checkpointing or heavy data movement.
4) Adjust for utilization
You rarely get 100% utilization. Estimate an efficiency factor:
- 90% = excellent
- 70–80% = common
- 50–60% = poor
Adjusted cost:
- effective cost = raw cost / utilization
- or effective hours = raw hours / utilization
Example:
- Raw GPU cost = $2,780
- utilization = 75%
- effective cost ≈ $3,707
5) Compare clouds using normalized metrics
Don’t compare only sticker price. Compare:
- $/GPU-hour
- throughput per GPU on your workload
- availability and queue time
- spot interruption rate
- data transfer costs
- ease of scaling
A cheaper GPU cloud can still be more expensive if:
- its GPUs are slower for your model
- networking is weak for multi-node training
- you lose time to preemptions or provisioning delays
6) Use a simple spreadsheet
Columns:
- Provider
- GPU type
- GPUs required
- Hourly GPU price
- Estimated training hours
- Utilization factor
- Storage/network overhead
- Retry buffer
- Total estimated cost
Formula:
- Total = GPUs × hourly price × hours / utilization + overhead + retry buffer
7) Add a safety buffer
Use a contingency buffer of:
- 10–20% for well-understood jobs
- 25–50% for first-time runs, large distributed jobs, or unstable pipelines
Quick example
You want to train on 4 GPUs for 60 hours.
Provider A:
- $3.00/GPU/hr
- utilization 80%
- storage/network overhead $40
Estimate:
- raw = 4 × 3 × 60 = $720
- adjusted = 720 / 0.8 = $900
- total = 900 + 40 = $940
Provider B:
- $2.20/GPU/hr
- utilization 65%
- overhead $80
Estimate:
- raw = 4 × 2.2 × 60 = $528
- adjusted = 528 / 0.65 = $812
- total = 812 + 80 = $892
Even though B has cheaper GPUs, the overall savings are modest once utilization and overhead are included.
Best practical method
- Run a small pilot on each candidate cloud.
- Measure throughput and utilization.
- Extrapolate to full training.
- Compare all-in cost, not just GPU price.
If you want, I can help you build a cost estimation template or a spreadsheet formula for specific clouds (AWS, GCP, Azure, Lambda, CoreWeave, Runpod, etc.).