A remote build cache pays off when reusing task outputs costs less than executing them again. Measure that difference in your own pipeline before estimating a return. Build compute, pipeline elapsed time, and developer waiting time are separate quantities.
Start with a repeatable measurement
Follow the remote build cache benchmark guide: run an uncached baseline, seed an isolated remote workspace, then replay from a fresh runner at the same commit. Keep dependencies, runner resources, tool versions, and task selection constant. Record every sample and report the median and range. Check both identical-commit reuse and representative changes.
- Task durations estimate compute work avoided. Parallel tasks do not add up to pipeline elapsed time.
- Job duration determines runner charges under time-based billing. Include downloads, extraction, and uploads.
- Developer waiting time counts only when someone is blocked. A background build is not automatically lost engineering time.
- Fixed-cost runners may gain capacity without reducing this month's bill.
Calculate runner savings
Monthly runner savings = avoided billable runner minutes x effective price per minute
Monthly net savings = runner savings - cache service cost - additional operating cost
ROI (%) = 100 x monthly net savings / (cache service cost + additional operating cost)Use your actual runner plan, included minutes, billing increments, and operating costs. If the denominator is zero, report net savings instead of an ROI percentage. For workflows with several jobs, sum the billable reduction across jobs rather than multiplying the workflow's critical-path change by every runner.
Here is an illustrative calculation, not a Cachely benchmark or a runner price quote. Suppose 800 monthly runs each avoid 6 billable minutes, your effective runner rate is $0.01 per minute, and a cache plus its operation costs $30 per month:
800 runs x 6 minutes x $0.01 = $48 monthly runner savings
$48 - $30 = $18 monthly net savings
100 x $18 / $30 = 60% ROIWith the same workload inside unused included runner minutes, immediate cash savings could be zero. Replace every assumption with a measured value before using this model to make a purchase. The CI savings calculator helps explore assumptions; it does not establish what your builds will save.
Keep developer time separate
A faster feedback loop can matter even when the runner bill barely changes. Sample how often engineers actually wait for a build and how much of the elapsed reduction removes that wait. Report hours of blocked work avoided separately from cash savings. Multiplying all build minutes by an engineer's hourly cost assumes every minute blocks a person and otherwise becomes productive work; that needs evidence.
Compare managed and self-hosted costs
- Managed: subscription, included storage and requests, limits, retention, and any usage charges.
- Self-hosted: storage, requests, network egress, compute, monitoring, upgrades, access control, and incident response.
- Both: setup time, input and output configuration, token rotation, and ongoing cache-hit diagnosis.
Use current Cachely pricing and limits and the same workload assumptions for each option. Managed caching reduces backend operation, but your team still owns correct build inputs and trusted writes. Data-location requirements or existing infrastructure may favor self-hosting; a small team may value avoiding that operational work. The remote cache comparisoncovers these choices.
Decide where caching helps
Expensive deterministic tasks with repeated inputs are good candidates. Large artifacts, low reuse, fast tasks, or slow network paths can make a remote hit more expensive than execution. Inspect why tasks miss, then compare elapsed results before expanding cache coverage. Start with one representative workload and keep a dated measurement record so changes in the task graph do not hide a regression.