Fly Machines vs AWS Lambda MicroVMs: Firecracker by the machine or the baseline

Both run Firecracker. A Fly Machine is priced by size while started, a MicroVM by its baseline each second: $1.44 against $4.20 for the benchmark.

Runtime costs 55% less than a Fly Machine and 85% less than a Lambda MicroVM on it. One thousand one-minute runs of a 2 vCPU, 4 GiB sandbox, each with 20 CPU-seconds of work, are $1.44 on Fly Machines, $4.20 on AWS Lambda MicroVMs and $0.64 on Runtime.

At a glance

	Fly Machines	AWS Lambda MicroVMs	Runtime
Isolation	Firecracker microVM	Firecracker microVM	Firecracker microVM, own kernel
Price	performance-2x with 4 GB, $0.0861 an hour, iad	$0.2522 an hour for 2 vCPUs and 4 GB	$0.03125 an hour waiting, $0.08 busy, for 2 and 4 GiB
Largest	16 performance vCPUs and 128 GB	A 4 vCPU, 8 GB baseline	16 vCPUs and 64 GiB, paid
Idle	Root disk is temporary; suspend at 2 GB or less	Suspend keeps memory and disk, up to 8 hours	Pause keeps memory and processes, 1 to 365 days
Regions	18	AWS regions	One US region

Same hypervisor, a third of the price

A performance vCPU on Fly is a whole core held for the Machine, and still the shape costs about a third of Lambda's per hour. Lambda's premium buys AWS integration and suspend with memory for up to eight hours; Fly's Machines suspend only at 2 GB of memory or less.

Cost for the same job

2 vCPU, 4 GiB, 60 seconds a run, 20 CPU-seconds of work, 1,000 runs:

TextMachines  Size   1,000 × 60 s / 3,600 × $0.0861                = $1.44Lambda    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

Both rivals charge by size, so keeping both CPUs busy for the whole minute changes neither: $1.44 on Machines and $4.20 on Lambda, with $1.33 on Runtime.

Which one to pick

• Fly Machines for long-running apps in many regions, alongside Fly's volumes and Postgres.
• Lambda MicroVMs for sandboxes tied into AWS identity and networking.
• Runtime for agent sandboxes at the lowest cost, with memory kept across pauses for up to a year.

See Runtime vs Fly.io and Runtime vs AWS Lambda MicroVMs.

Sources

Fly Machines rates checked 23 September 2026; Lambda MicroVMs rates checked 25 September 2026.

• Fly.io pricing
• AWS Lambda pricing, Lambda MicroVMs
• Runtime pricing

Facts on this page were checked on 25 September 2026.