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Savings Plans vs On-Demand calculator
A steady compute baseline paid for on demand leaves 20% to 50% behind. The catch is that committing to the wrong number turns the discount into a liability, so the order you do things in matters more than the term you pick.
EC2 + Fargate + Lambda, the steady baseline only — not spiky batch workloads.
1-year no-upfront is the sane first commitment for most SMEs.
On-demand today
$2,000.00/month
$24,000.00/year · ≈ £1,560/month
With 1 year, no upfront
$1,600.00/month
$19,200.00/year · ≈ £1,248/month
Your saving
$400.00/month
$4,800.00/year · ≈ £312/month
| Option | Typical discount | Saving on your spend |
|---|---|---|
| 1 year, no upfront | ~20% | $400.00/mo · $4,800.00/yr |
| 1 year, all upfront | ~25% | $500.00/mo · $6,000.00/yr |
| 3 years, no upfront | ~40% | $800.00/mo · $9,600.00/yr |
| 3 years, all upfront | ~50% | $1,000.00/mo · $12,000.00/yr |
Conservative estimates for Compute Savings Plans on Linux in common regions — your exact discount depends on instance families and regions. AWS’s Cost Explorer recommendation engine (which our scan reads) quotes the precise number for your account.
Commit to the right baseline: the free scan pulls AWS’s own Savings Plan recommendation for your account — after flagging the idle instances you should stop first, so you don’t commit to waste.
Estimate the whole billThe rules nobody tells you
- →Rightsize before you commit. A Savings Plan locks in your spend level. Buy one while idle and oversized instances are still running and you have prepaid for waste at a discount. Clean up first, then commit to the smaller baseline.
- →Commit under your baseline rather than at it. Aim at 80% to 90% of your steady usage after the cleanup. The uncovered slice bills on demand, which is fine, and over-committing costs you more than under-committing does.
- →Coverage matters more than the headline discount. The number to watch is what share of your compute runs covered. Zero coverage on a steady workload is one of the most common things a cost review turns up.
- →Databases have their own reservations. Savings Plans do not cover RDS, ElastiCache, OpenSearch or Redshift. Steady database nodes want Reserved Instances instead, at similar discounts, bought separately, and forgotten just as reliably.
- →Set a renewal reminder. Plans expire silently and everything reverts to on-demand. A calendar entry a month before expiry is worth hundreds.
Frequently asked questions
What is a Compute Savings Plan?
A commitment to spend a fixed amount an hour on compute, say $2, for one or three years. That spend is then billed at a discount, from around 20% on a one year no upfront plan to over 50% on three years all upfront. It applies across EC2 instance families, regions, Fargate and Lambda, so it survives most changes to your stack.
Should I buy Savings Plans or Reserved Instances?
For most companies of this size, Compute Savings Plans, because they survive instance family changes, region moves and container migrations that would strand a Standard RI. Reserved Instances still win for steady RDS, ElastiCache, OpenSearch and Redshift nodes, which have their own reservation types and are worth buying separately.
What happens if my usage drops below the commitment?
You pay the committed amount anyway, so unused commitment is money gone. That is why rightsizing comes first: stop the idle instances, downsize the oversized ones, and only then commit to the smaller baseline that is left. Committing to today's inflated usage locks the waste in for a year.
Which term should a smaller company pick first?
One year, no upfront. It saves around 20%, costs nothing in cash up front, and a year is short enough that an architecture change will not strand you. Three year plans save considerably more but assume you can predict your stack in 2029, which most companies under fifty people cannot.
How do I know the exact discount for my account?
Cost Explorer has a Savings Plans recommendation engine that reads your last 30 to 60 days and quotes an exact hourly commitment and saving. Our free scan reads that same recommendation and reports it next to the idle instance findings you should deal with first.