Read the cost report

microvm cost --estimate --memory 1024 --running-sec 1800 --image-gb 2
microvm cost --estimate --compare --memory 2048 --hold-sec 28800 --cycles 4
microvm cost --estimate --memory 2048 --running-sec 3600 --max-cost 1.50 --on-breach abort

Every run reports a cost estimate, and microvm cost produces the same report over durations you supply. At the end of this page you will know what each figure is built from, what it means when a total says “at least”, and how to put a budget on a run before it launches.

1. Where the figures come from

Rates are pinned, dated, and per region, and only the ARM rates apply, because the service’s architecture enum has one member. Dollar figures are estimates derived from published rates, never an invoice. mise run live:rates checks the pinned table against the AWS Pricing API, and the report carries a staleness note when the pinned date is old.

Anything the engine cannot price is reported as unpriced with a reason, and an unpriced line omits usd rather than reporting zero. The server-side image build is the usual case: AWS has not published whether a build bills as compute, so --build-sec puts an unpriced line on the report.

2. What bills

Compute bills per second while the VM is RUNNING, as separate vCPU and memory line items. The baseline you request with --memory is the floor you pay for every running second, the VM is provisioned at four times it from the start, and usage above the baseline bills by what is consumed. Idle time while RUNNING bills at baseline, so suspension is the only way to stop paying.

Snapshots bill three ways. Image storage bills per GB-hour with a one-week minimum retention, so a 2 GB image deleted sixty seconds after creation still bills about a week of storage. A suspended VM pays snapshot storage only, about $0.16 a month for a 2 GB VM against roughly $100 a month left running at baseline. Each suspend/resume cycle pays a snapshot write plus a read, about $0.011 for a 2 GB VM, so the thing to avoid is cycling constantly; a long suspension is cheap.

Rates vary by region. us-east-2 and us-west-2 match us-east-1 on every line; eu-west-1 and ap-northeast-1 are higher, most of all on the snapshot dimensions, so a design that leans on a suspended pool should price in its own region. Data transfer bills at standard AWS rates and is not on the report. The measurements are in Platform, under “What actually costs money”.

3. A total may be a lower bound

A total over any unpriced line is a different kind of total. It renders as at least $X, and under --json the budget verdict carries basis: "lower-bound" where a fully priced report carries basis: "exact". A verdict from a lower bound says so in both directions: a breach detected from a floor has already been exceeded by an unknown margin, and an under-budget floor proves nothing, so the text says which lines are unpriced beside the figure.

4. Plan before you spend

--estimate treats the durations as a plan rather than as timings, and every duration on such a report is labelled projected, so an estimate cannot print as a report of something that ran. --running-sec, --suspended-sec, and --build-sec are the phases; --image-gb adds storage with its one-week minimum retention; --cycles counts suspend/resume cycles, each paying a snapshot write plus a read.

--compare also prints running versus suspended for the same hold, with the break-even, over --hold-sec (default 3600).

--max-cost is a budget in USD the report’s total is checked against, and --on-breach says what a breach does: warn warns and exits 0, abort aborts with ERR_PRECONDITION (exit 12). The pair is required together, because whether a breach of a lower-bound total should stop a script is the caller’s judgement and has no default. Under --json the budget key carries maxUsd, onBreach, basis, breached, and overageAtLeastUsd.

5. Size for the bill

--memory selects a size class, and the guest reports the class’s peak in /proc/meminfo:

Baseline (billed while running)	Peak (provisioned ceiling)
512 MiB, 0.25 vCPU	2 GB, 1 vCPU
1024 MiB, 0.5 vCPU	4 GB, 2 vCPU
2048 MiB, 1 vCPU (default)	8 GB, 4 vCPU
4096 MiB, 2 vCPU	16 GB, 8 vCPU
8192 MiB, 4 vCPU	32 GB, 16 vCPU

For peaky workloads such as builds, test runs, and agent sessions, pick a low minimum and let the peaks ride the always-present headroom, which bills only by what is consumed. Guest swap is absent, so pressure past the peak goes straight to the OOM killer. The value is also a microvm.toml key, memory, validated against the same closed set.

6. On the run envelope

A run envelope carries the report under cost, and the human rendering ends with a cost: line. buildSeconds and runningSeconds beside it are the measured phases the report was built from. Because the image snapshot’s one-week minimum applies whether or not you keep the image, reusing it with --image is the economical habit; your first run shows the loop.