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Estimating, contracts and getting paid.

Worked examples, arithmetic you can check, and the mistakes we see most often in real contractor estimates. Written for people who price construction work in Ghana.

Estimating · 6 min read

Markup is not margin, and the difference is your salary

Adding 20% to your cost does not give you a 20% margin. On a GHS 500,000 job that mistake is worth about GHS 16,000 — roughly what most small contractors take home in a quarter.

Obed Buadey · Founder, EstimatePro Africa · 29 Jul 2026

markup %  =  (price − cost) ÷ cost × 100
margin %  =  (price − cost) ÷ price × 100

cost      GHS 400,000
+ 20%     GHS  80,000
price     GHS 480,000
margin         16.7%   ← not 20%

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Notebook of rates on a site table — A rate book kept by hand, KumasiThe practice this writing came from

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