Source: https://www.quantsurv.com/library/glossary/rom
Content format: Markdown version of the public page.
Content reviewed: 2026-10-10

# ROM (rough order of magnitude)

An early, rough estimate of cost, given before the design is developed enough to price properly.

by [Jack Butler-Kettle](<https://www.quantsurv.com/about#jack-butler-kettle>) · About 1 min readShare

## Further detail

Read this alongside [NRM 2: Detailed measurement for building works](<https://www.rics.org/content/dam/ricsglobal/documents/standards/NRM-2_Oct2022_Update.pdf>).

A rough order of magnitude is an early estimate based on limited information. It should state assumptions, exclusions, uncertainty and the purpose for which it can be used. It is different from an agreed quotation or a supported claim calculation, even when all three are expressed in pounds.

Label the estimate's scope, assumptions, exclusions and uncertainty as information develops. Our [Construction estimating and cost planning](<https://www.quantsurv.com/quantity-surveying?service=%2Fquantity-surveying%2Fcost-planning-estimating#client-types>) service prepares an early budget on that stated basis and reconciles later revisions.

## Sources

1.  [NRM 2: Detailed measurement for building works, UK 2nd edition, October 2021 (reissued October 2022 as RICS practice information)](<https://www.rics.org/content/dam/ricsglobal/documents/standards/NRM-2_Oct2022_Update.pdf>). RICS.

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