McKinsey 2015: The Source for "98% of Megaprojects Go Over Budget"
The most-cited megaproject overrun statistic traces to one McKinsey article. We give its exact wording, the exhibit behind the 80% figure, and the distinction between the 98% share and the 80% average.
Where does the "98% of megaprojects overrun" figure come from?
From McKinsey & Company's article The construction productivity imperative (Changali, Mohammad and van Nieuwland, 1 July 2015). Its text: "Our research estimates that 98 percent of megaprojects suffer cost overruns of more than 30 percent; 77 percent are at least 40 percent late." The 80% quoted next to it is from the same article's Exhibit 2: an average cost increase of 80% of original value, and an average slippage of 20 months. One is a share, the other an average.
Source: McKinsey, The construction productivity imperative (article), read 8 October 2026. Exhibit 2: PDF version.
The figures, kept apart
The most common mistake with this statistic is to quote it as "98% of megaprojects overrun by 80%". That fuses a count and an average. Here they are as the article presents them:
| Finding | Figure | Where in the article | What it measures |
|---|---|---|---|
| Megaprojects with a cost overrun above 30% | 98% | Text | A share |
| Megaprojects at least 40% late | 77% | Text | A share |
| Average cost increase, % of original value | 80% | Exhibit 2 | A magnitude |
| Average slippage behind original schedule | 20 months | Exhibit 2 | A magnitude |
A project only has to slip just past 30% over budget to count toward the 98%. The 80% average is pulled up by a long tail: Exhibit 2's vertical axis runs to 650% of the original quoted capital expenditure. Cite whichever you mean, and do not multiply one by the other.
What projects are behind it
Exhibit 2 is titled "Ninety-eight percent of megaprojects face cost overruns or delays". It plots megaprojects in three sectors (mining, oil and gas, and infrastructure), numbered 1 to 63, by capital-expenditure overrun against delay in years. Its sources are companies' public annual reports, press releases, and the IHS Herold Global Projects Database (19 November 2013). McKinsey does not publish the project list, so the sample cannot be reproduced.
Note the wording gap: the exhibit caption says "98% of projects incur cost overruns or delays", while the article text says 98% "suffer cost overruns of more than 30 percent". If you need the stricter claim, quote the text and say so.
How it fits the wider evidence
- Flyvbjerg, Holm & Buhl (2002): cost was underestimated in almost 9 in 10 of 258 transport infrastructure projects, by 28% on average (JAPA, author copy, read 8 October 2026).
- Flyvbjerg and Gardner (2023): of 16,000-plus projects, 8.5% came in on budget and on time and 0.5% also delivered their benefits (How Big Things Get Done (book; figure as quoted, not checked against the page)).
- The Olympic Games: all 23 Games from 1960 to 2024 with available data overran, by 159% on average in real terms (Ansar, Flyvbjerg and Budzier 2026, read 8 October 2026).
Different methods and samples, the same direction.
How to cite
Document: mckinsey.com, The construction productivity imperative, read 8 October 2026
Frequently Asked Questions
Where does the "98% of megaprojects go over budget" statistic come from?
From McKinsey & Company's article 'The construction productivity imperative' by Sriram Changali, Azam Mohammad and Mark van Nieuwland (1 July 2015). Its text says: 'Our research estimates that 98 percent of megaprojects suffer cost overruns of more than 30 percent; 77 percent are at least 40 percent late.' The '80%' quoted next to it comes from the same article's Exhibit 2, which reports an average cost increase of 80% of original value and an average slippage of 20 months.
Is the 98% figure the same as the 80% figure?
No. The 98% is a share (how many megaprojects overrun by more than 30%). The 80% is a magnitude (the average cost increase across the megaprojects plotted in Exhibit 2). Quoting '98% overrun by 80%' fuses a count and an average.
What projects are behind the McKinsey figures?
Exhibit 2 plots megaprojects in three sectors (mining, oil and gas, and infrastructure), numbered 1 to 63, using companies' public annual reports, press releases and the IHS Herold Global Projects Database (November 2013). The exhibit's own caption reads '98% of projects incur cost overruns or delays', which is looser than the article text's 'cost overruns of more than 30 percent'. McKinsey does not publish the project list.
Is the 98% figure in McKinsey's 'Megaprojects: the good, the bad, and the better'?
No. That article, published the same month, cites Bent Flyvbjerg's finding that nine out of ten megaprojects go over budget and gives McKinsey estimates of 35% average overrun for bridges and tunnels and 20% for roads. It does not contain the 98% or 80% figures. This site previously attributed them to it; that was our error, corrected on 8 October 2026.