Scale Out vs Scale Up Calculator

Work out scale out vs scale up instantly with clear inputs, formula shown and shareable results.

About Scale Out vs Scale Up Calculator

When pricing is linear in size, scale-out and scale-up cost the same per unit of capacity, so the decision comes down to granularity and failure domain. Large instances round up more coarsely, wasting capacity, and each one takes a bigger share of the fleet with it when it fails. Scale-up wins where per-instance licensing, memory locality or single-threaded performance dominate.

Formula

Cost comparison

scale out = ceil(required / small units) x small cost; scale up = ceil(required / (small units x multiplier)) x small cost x multiplier

Worked example

With the default values below, Scale Out vs Scale Up Calculator returns Lower-cost option of Scale out with 16 small instances. Change any input above and every figure here is recalculated in your browser.

Inputs used

Capacity requiredminimum 1 units: 64 units
Monthly cost of a small instanceminimum 0.01: 70
Capacity per small instanceminimum 0.1 units: 4 units
Large instance size multiplieraccepts 1.1–64 x: 8 x

Results

Lower-cost option: Scale out with 16 small instances
Scale-out monthly cost: $1,120.00
Scale-up monthly cost: $1,120.00
Capacity wasted by rounding up to large instances: 0.0 units

Step by step

1Values used
2Cost comparison
3Lower-cost option= Scale out with 16 small instances
4Scale-out monthly cost= 1,120.00
5Scale-up monthly cost= 1,120.00
6Capacity wasted by rounding up to large instances= 0.0 units

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax or compounding frequency into account.
Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

If cost is equal, which should I choose?

Scale out, generally. Smaller failure domains, finer autoscaling granularity and easier rolling updates all favour more, smaller instances.

When does scale-up clearly win?

Per-socket or per-instance licensing, large in-memory working sets that must not be partitioned, and workloads that cannot be parallelised across processes.