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

Use microvm cost to estimate a workload before launching it. Read the price sources and unpriced items before using the total as a budget. A partial total is a lower bound on the cost.

1. Check the rate sources

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

A VM in RUNNING bills for vCPU and memory each second. The baseline set by --memory is the floor you pay for, even when the VM is idle. The guest has four times that capacity from launch. Usage above the baseline adds a charge for what it consumes. Suspend the VM or call terminate when it can stop.

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 incurs snapshot storage charges. Each suspend/resume cycle adds a snapshot write and read; use the calculator with the intended region, size, duration, and cycle count to compare alternatives.

Rates vary by region. us-east-2 and us-west-2 match us-east-1 on every line, and every other region charges more on the snapshot lines, by up to 60%, 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

When any line lacks a price, the total reads at least $X. In --json, the budget result has basis: "lower-bound". A report with all prices has basis: "exact".

If the floor exceeds your budget, the full cost does too. If the floor is within budget, the full cost may still exceed it. Read the unpriced lines beside the total before deciding to proceed.

4. Plan before you spend

--estimate treats the durations as a plan rather than as timings, and every duration on such a report is labeled 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. Left off, the report counts none, because a report claims only what you say happened, so a report of a run that suspended takes --cycles.

--compare also prints running versus suspended for the same hold, with the break-even, over --hold-sec (default 3600). The comparison prices one suspend/resume cycle when --cycles is left off, to include the cost of that cycle, and a --cycles you give feeds both the report and the comparison.

--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 judgment 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.