Which is better, Runloop or Prime Sandboxes?
It depends on whether you need tooling or volume. For eval jobs that mostly wait on a model, Runtime costs $0.64 for the benchmark, against $1.52 on Prime and $5.33 on Runloop. Runtime also runs suites through Harbor or Inspect. Pick Runloop for managed evaluation tooling and compliance statements. Pick Prime Sandboxes for RL rollouts by the thousand on Prime's platform.
At a glance
| Runloop | Prime Sandboxes | Runtime | |
|---|---|---|---|
| Isolation | microVM, with a container inside | Hardware-virtualized microVM, own guest kernel | Firecracker microVM, own kernel |
| CPU | $0.108 per CPU-hour while running | $0.02 per vCPU-hour while running | $0.025 per vCPU-hour of measured CPU, with a small floor |
| Memory | $0.0252 per GB-hour | $0.0125 per GiB-hour | $0.0075 per reserved GiB-hour |
| Evals | Evaluation on your own workload, RL rollouts | Environments for Prime's RL training | Harbor and Inspect integrations |
| Plan | Basic free; Pro $250 a month plus usage | None; rates through 22 December 2026 | None; prepaid credit from $10 |
Tooling against price
Runloop sells evaluation tooling: models evaluated on your own workload and RL rollouts checked by running them, with compliance statements for enterprises. Prime sells the environment at a low price and with very high parallelism. Runtime plugs into the harnesses teams already use, Harbor with Terminal-Bench and Inspect, and charges less per rollout than either.
Cost for the same job
The benchmark, 60 seconds a run (a MEDIUM devbox with 8 GB of disk; Prime
with 5 GiB):
- CPU
- 1,000 × 60 s / 3,600 × 2 × $0.108
- $3.60
- Memory
- 1,000 × 60 s / 3,600 × 4 × $0.0252
- $1.68
- Disk
- 1,000 × 60 s / 3,600 × 8 × $0.00034236
- $0.05
- CPU
- 1,000 × 60 s / 3,600 × 2 × $0.02
- $0.67
- Memory
- 1,000 × 60 s / 3,600 × 4 × $0.0125
- $0.83
- Disk
- 1,000 × 60 s / 3,600 × 5 × $0.0002
- $0.02
- CPU
- 1,000 × 20 s / 3,600 × $0.025
- $0.14
- Memory
- 1,000 × 60 s / 3,600 × 4 × $0.0075
- $0.50
With both CPUs busy for the whole minute, the job costs $5.33 on Runloop, $1.52 on Prime and $1.33 on Runtime.
Which one to pick
- Runloop for managed evaluation tooling and compliance statements.
- Prime Sandboxes for RL rollouts by the thousand.
- Runtime for eval runs at the lowest price, through Harbor or Inspect.
See Runtime vs Runloop and Runtime vs Prime Sandboxes.
Runtime Cloud
Runtime runs the benchmark for 88% less than Runloop and 58% less than
Prime. 1,000 one-minute runs of a 2 vCPU, 4 GiB sandbox, 20 CPU-seconds of
work each: $5.33 on a Runloop MEDIUM devbox, $1.52 on Prime Sandboxes, $0.64
on Runtime.
Log in with npx withruntime login to run on the free usage. Use the
migration guide to move a Runloop or Prime harness.
Sources
Runloop rates checked 25 October 2026; Prime Sandboxes rates checked 25 October 2026.
Facts on this page were checked on 26 October 2026.