Runtime costs 58% less than Prime Sandboxes for an agent that waits on a model. 100,000 one-minute runs of a 2 vCPU, 4 GiB sandbox, each using 20 CPU-seconds, cost $63.89 a month on Runtime and $151.67 on Prime. Prime's CPU rate is lower than Runtime's, but it is charged for every vCPU the whole time, and its memory costs two thirds more. Rates checked 25 October 2026.
How Prime Sandboxes bill
A Prime sandbox is billed while it runs, for the CPU, memory and disk it was given. Its defaults are 1 vCPU, 1 GiB and 5 GiB of disk, and it can grow to 16 vCPUs, 64 GiB and 128 GiB of disk.
| Meter | Prime, as published | For 2 vCPUs, 4 GiB and 5 GiB of disk | Runtime |
|---|---|---|---|
| CPU | $0.02 per vCPU per hour | $0.04 an hour | $0.025 per vCPU-hour of CPU used |
| Memory | $0.0125 per GiB per hour | $0.05 an hour | $0.0075 per reserved GiB-hour |
| Disk | $0.0002 per GiB per hour | $0.001 an hour | Included while it runs |
So the shape is $0.091 an hour on Prime, working or waiting. On Runtime it is $0.03125 an hour while it waits and $0.08 with both CPUs busy, so Runtime costs less at every level of use. The calculator keeps Prime's 5 GiB default disk for every shape.
Example workloads
A month of each, from the calculator above.
| Workload | Runtime | Prime Sandboxes |
|---|---|---|
| Agent runs: 2 vCPU, 4 GiB, 60 s, 20 CPU-seconds, 100,000 a month | $63.89 | $151.67 |
| Waiting agents: 2 vCPU, 4 GiB, 30 min, 180 CPU-seconds, 10,000 | $162.50 | $455.00 |
| Tool calls: 1 vCPU, 2 GiB, 2 min, 30 CPU-seconds, 50,000 | $35.42 | $76.67 |
| Every CPU busy: 2 vCPU, 4 GiB, 60 s, 120 CPU-seconds, 100,000 | $133.33 | $151.67 |
The first three rows save 54% to 64%. The last is the closest Prime comes. With the CPUs never idle, Runtime is 12% cheaper.
Rollouts that wait on a model
Prime built its sandboxes for agentic reinforcement learning, where thousands of rollouts each run a few tool calls between long waits for the policy model. That is the shape where measured CPU pays most: a rollout that computes for 20 seconds of every minute costs 58% less on Runtime than on Prime. Runtime's forks help the same work, since one set-up environment becomes up to 100 running copies with memory included. Prime's checkpoints and forks save the filesystem only, so processes start fresh.
What the calculator leaves out
- The end of launch pricing. Prime publishes these rates through 22 December 2026. Runtime's rates are fixed in each resource's quote.
- Free start. Prime publishes none. Runtime gives 100 free hours of a 1 GB machine in the first 30 days, no card.
- Network. Left out on both sides.
Price your own runs exactly
After a few runs on Runtime, the CLI prices those same sandboxes at Prime's published rates:
Terminalruntime compare --from primeIt reads your settled sandboxes from the last 30 days (--days up to 90). The
full comparison is Runtime vs Prime Sandboxes,
agent evals and SWE-bench shows
evaluation runs on Runtime, and the
sandbox cost calculator prices every
provider for your shape.
Sources
- Prime Sandboxes overview, checked 25 October 2026
- Prime Sandboxes launch
- Runtime pricing
Rival rates on this page were checked on 26 October 2026.