Runtime

Modal vs AWS Lambda MicroVMs: serverless sandboxes compared

Modal isolates sandboxes with gVisor and Lambda MicroVMs with Firecracker. For 1,000 one-minute 2 vCPU runs, Modal costs $3.97 and Lambda $4.20.

Runtime runs the same work for 84% less than Modal and 85% less than Lambda MicroVMs. Both rivals come from serverless functions and bill a sandbox for what it reserved: Modal the larger of its request and its use, Lambda its baseline. Runtime measures CPU, so the benchmark, 1,000 runs of a 2 vCPU, 4 GiB sandbox with 20 CPU-seconds of work, costs $0.64 there.

Estimated compute cost

84% less than Modal85% less than AWS Lambda MicroVMs

2 vCPUs · 4 GiB · 60 s a run · 20 CPU-seconds busy

1,000

Compute only, at list rates checked 23 September 2026 and 25 September 2026 (Modal pricing, AWS Lambda pricing). Plan fees, network, taxes and free credits are left out. The worked example below shows the arithmetic.

At a glance

Modal Sandboxes AWS Lambda MicroVMs Runtime
Isolation gVisor, a user-space kernel Firecracker microVM Firecracker microVM, own kernel
CPU $0.1419 per physical core-hour (2 vCPUs), request or use $0.0997 per baseline vCPU-hour $0.025 per vCPU-hour of measured CPU, with a small floor
Memory $0.0240 per GiB-hour, request or use $0.0132 per GB-hour $0.0075 per reserved GiB-hour
Lifetime Up to 24 hours; snapshots carry state beyond State kept up to 8 hours Leases extended as needed, or persistent
Plan Starter $0 with $30 a month; Team $250 a month None; an AWS account None; prepaid credit from $10
GPUs Yes, beside Modal functions No No

A shared lineage, different kernels

Modal and Lambda both grew sandboxes out of a functions platform, so both fit teams already deploying there. The difference that matters for untrusted agent code is the boundary: gVisor intercepts system calls in a user-space kernel, while a Lambda MicroVM, like a Runtime sandbox, runs its own guest kernel under a hypervisor. See gVisor vs Firecracker.

Cost for the same job

1,000 runs, 60 seconds each, 20 CPU-seconds of work, 2 vCPU and 4 GiB (one physical core on Modal, a 4 GB baseline on Lambda):

TextModal     CPU    1,000 × 60 s × 1 core × $0.00003942           = $2.37          Memory 1,000 × 60 s × 4 × $0.00000667                = $1.60          Total                                                  $3.97Lambda    CPU    1,000 × 60 s × 2 × $0.0000276944              = $3.32          Memory 1,000 × 60 s × 4 × $0.0000036667              = $0.88          Total                                                  $4.20Runtime   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

For 100,000 runs a month: $396.60 on Modal, $420.33 on Lambda, $63.89 on Runtime. Kept busy for the whole minute on both CPUs, the job still costs $3.97 on Modal and $4.20 on Lambda, and $1.33 on Runtime.

Which one to pick

  • Modal when sandboxes sit beside GPU functions and scheduled jobs.
  • Lambda MicroVMs when the rest of the system is on AWS and must stay inside your VPC and IAM.
  • Runtime for Firecracker at a sixth of either bill, sandboxes up to 16 vCPUs and 64 GiB, and pauses that keep memory for up to a year.

More: Runtime vs Modal, Runtime vs AWS Lambda MicroVMs.

Sources

Modal rates checked 23 September 2026; Lambda rates checked 25 September 2026.

Facts on this page were checked on 25 September 2026.

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