# Modal vs Blaxel: pricing, isolation and limits Modal bills a sandbox's requested core and memory under gVisor; Blaxel bills memory only while active and nothing for compute in standby. **Between runs Blaxel is cheap and Modal is not; within a run, only Runtime bills by use, which puts it 84% below Modal and 77% below Blaxel.** 1,000 one-minute runs of a 2 vCPU, 4 GiB sandbox cost $3.97 on Modal, $2.76 on Blaxel and $0.64 on Runtime. Runtime charges measured CPU plus memory at $0.0075 a GiB-hour, inside a Firecracker microVM with its own kernel. Rates checked 23 September 2026. ## At a glance Modal's CPU unit is the physical core, equal to two vCPUs. | | Modal Sandboxes | Blaxel | Runtime | | ------------- | --------------------------------------------------------- | ---------------------------------------------------- | -------------------------------------------------------- | | Isolation | gVisor, a user-space kernel that intercepts system calls | Lightweight virtual machines | Firecracker microVM, own kernel | | CPU | $0.1419 per physical core-hour (2 vCPUs), request or use | Included with memory; 8 GB gets 4 cores | $0.025 per vCPU-hour of measured CPU, with a small floor | | Memory | $0.0240 per GiB-hour, request or use | $0.0000115 per GB-second of active time ($0.0414/h) | $0.0075 per reserved GiB-hour | | When idle | Billed until `timeout` or `idle_timeout` ends it | Standby about 15 seconds after connections close | Pause on request or after an idle time you set | | Keeping state | Filesystem snapshots | Standby snapshot, $0.20 per GB-month | Paused storage with memory, $0.08 per GB-month | | Resume | A new sandbox from a snapshot | About 25 ms from standby | Wakes with files, memory and processes | | At once | 100 containers on Starter; 5,000 on Team | 10 sandboxes on Tier 0; over 100,000 on the top tier | 8 on the trial; 100 to start on a paid account | | Plan fee | Starter $0 with $30 a month of compute; Team $250 a month | None; tiers grow with credit added | None; prepaid credit from $10 | | Free start | $30 of compute a month on Starter | Up to $200 of credit | 50 sandbox hours, no card | ## What does an idle sandbox cost? This is the widest gap between the two rivals. A Modal sandbox bills its requested core and memory for as long as it runs, whether its code is working or waiting. It runs until its `timeout`, 5 minutes by default and up to 24 hours, or until `idle_timeout` ends it; state that must outlive it goes into a filesystem snapshot for the next sandbox. A Blaxel sandbox goes to standby by itself about 15 seconds after its last connection closes. Standby costs nothing for compute, only $0.20 per GB a month for the snapshot, and the sandbox resumes in about 25 ms. A Runtime sandbox pauses when you call `pause()`, or after the `idlePauseSeconds` you set, and keeps its files, memory and running processes for 1 to 365 days at $0.08 per GB a month. A request to a paused sandbox wakes it. While it runs, the waiting is cheap too: CPU is billed as measured, with a floor of a twentieth of a vCPU. ```ts check import { Sandbox } from "withruntime"; const sbx = await Sandbox.create({ timeoutSeconds: 600 }); await sbx.exec("echo state > /workspace/state.txt"); await sbx.pause(); // memory and files are kept; compute billing stops // ... later, even from another process: const again = await Sandbox.connect(sbx.id); await again.wake({ timeoutSeconds: 1200 }); await again.extend(600); // more time before the lease ends await again.stop(); ``` ## Cost for the same job The job: 1,000 runs, 60 seconds each, on 2 vCPU and 4 GiB (a single physical core on Modal, 4 GB on Blaxel), with 20 CPU-seconds of real work per run. ``` Modal CPU 1,000 × 60 s × 1 core × $0.00003942 = $2.37 Memory 1,000 × 60 s × 4 × $0.00000667 = $1.60 Total $3.97 Blaxel Memory 1,000 × 60 s × 4 × $0.0000115 = $2.76 Runtime CPU 1,000 × 20 s / 3,600 × $0.025 = $0.14 Memory 1,000 × 60 s / 3,600 × 4 × $0.0075 = $0.50 Total $0.64 ``` At 100,000 runs a month, Modal bills $396.60, Blaxel $276.00 and Runtime $63.89. With both CPUs busy for the whole minute, it is $1.33 on Runtime, $3.97 on Modal and $2.76 on Blaxel. Blaxel is priced as if standby began the instant each run finished. Plan fees, snapshots, network and free credit are excluded. Inside a run, neither rival's price responds to load: Modal charges the request, and Blaxel charges memory with CPU folded in. Blaxel saves money only between runs, through standby. ## Which one to pick - **Modal**, if the sandboxes need GPUs or should live in the same SDK as your Modal functions, web endpoints and scheduled jobs. - **Blaxel**, if sandboxes spend long stretches asleep and must resume in milliseconds, or the fleet runs past 100,000 at once. - **Runtime**, if you want a microVM per sandbox at a sixth of Modal's price and under a quarter of Blaxel's, CPU billed as used within each run, and a pause that holds memory and processes for up to a year. ## Moving to Runtime Modal code ports one call at a time and drops the App: `modal.Sandbox.create(app=...)` is `Sandbox.create()`, `sb.exec(*args)` is `exec`, and `idle_timeout` is `idlePauseSeconds`. Blaxel code maps create to `Sandbox.create()` and a process to `exec`, while standby is replaced by automatic wake, on by default. Everything else is in the [migration table](/docs/migrate#map-the-calls). `npx withruntime compare --from blaxel` shows what your Blaxel sandboxes would have cost at Runtime's rates, and `npx withruntime switch --from modal` before the first top-up matches that top-up with credit, up to $100. A coding agent can do the port from the one instruction in [migration](/docs/migrate), on a branch, on the free trial. See [Runtime vs Modal](/docs/modal-sandbox-alternative) and [Runtime vs Blaxel](/docs/blaxel-alternative). ## Sources Modal pricing, Modal Sandboxes and Blaxel pricing pages rechecked 25 September 2026; the rest checked 23 September 2026. - [Modal pricing](https://modal.com/pricing), [Modal resources and billing](https://modal.com/docs/guide/resources), [Modal Sandboxes](https://modal.com/docs/guide/sandbox), [Modal security](https://modal.com/docs/guide/security) - [Blaxel pricing](https://blaxel.ai/pricing), [Blaxel sandboxes](https://docs.blaxel.ai/Sandboxes/Overview) - Runtime [pricing](/docs/pricing) Facts on this page were checked on 25 September 2026.