Estimate range check
Apply the published accuracy range for the class your estimate declares to the figure itself, and see where the approved number sits inside it.
The seamThe estimator who labelled the figure Class 4 and the board that approved it as a number, with the range the label carried left on the estimating side of the table.
The values below are an example, a Class 4 building estimate with a 5% margin approved above it. Replace them with your own.
The two matrices AACE publishes free are written for different industries and each says what it excludes.
As stated in its basis of estimate. This page does not determine the class: the RP says the deliverables do, not a percentage, and sets them out in its Table 3.
The figure the class is attached to, including the contingency the estimator applied. Any currency; the output is in the same one.
60,000,000
Optional. The number the board signed, the budget line, or the figure quoted in public. Leave blank to skip.
63,000,000
Estimate range check
2026-10-01. projects-advisors.com/tools/estimate-range
- Project type
- Building and general construction (56R-08)
- Class declared
- Class 4
- Estimate after contingency
- 60,000,000
- Approved figure
- 63,000,000
Published band applied to this estimate
48,000,000 to 78,000,000
A Class 4 estimate under 56R-08 carries a published range of -20% to +30% at its widest and -10% to +20% at its narrowest, at an 80% confidence interval, after contingency. At the wide bounds the band reaches 18,000,000 above the estimate and 12,000,000 below it; the high side is larger in every class of both tables.
| Bound | Published | On this estimate |
|---|---|---|
| Low, wide | -20% | 48,000,000 |
| Low, narrow | -10% | 54,000,000 |
| The estimate | 0% | 60,000,000 |
| High, narrow | +20% | 72,000,000 |
| High, wide | +30% | 78,000,000 |
| High, weak project system | +60% to +90% | 96,000,000 to 114,000,000 |
Where the approved figure sits
The approved figure carries +5% headroom over the estimate, inside the narrow high bound of +20%. The published band still reaches 15,000,000 above it at the wide bound.
56R-08, Table 1, revision of 7 August 2020, read in the free sample AACE publishes. The percentages are the typical variation of actual cost from the estimate at an 80% confidence interval, after a contingency set for roughly a 50% chance of overrun against underrun, so about one project in five is expected to land outside even the wide band. The narrow pair is for a favourable project, the wide pair for an unfavourable one, and the RP says which applies to yours can only be settled by a risk analysis of this project, never pre-determined. The last row is the RP's own statement that for weak project systems or complex and risky projects the high range may be two to three times what the table shows.
The class itself is what you told this page. The RP is explicit that a percentage of design complete should not be used to set it; the class rests on the maturity of named deliverables in the RP's Table 3. If the estimate's basis does not state its class with those deliverables, the class is the first thing to question, before any number here.
Computed from
- AACE International RP 56R-08, cost estimate classification for building and general construction, rev. 7 August 2020 (rev. 7 August 2020; read 2026-09-05)https://web.aacei.org/docs/default-source/toc/toc_56r-08.pdf
- AACE International RP 18R-97, cost estimate classification for the process industries, rev. 7 August 2020 (rev. 7 August 2020; read 2026-09-05)https://web.aacei.org/docs/default-source/toc/toc_18r-97.pdf