Every bid is a bet. Price too high and you lose the job to a competitor. Price too low and you win the privilege of working for free - or worse, finishing a project with a loss you have to absorb before you can move on to the next one. The math behind a winning bid starts with accurate direct costs (materials, labor, and equipment), adds an overhead allocation, applies your target profit margin, and then allows room for contingency. Most contractors skip the overhead allocation entirely, which means their "profit" is quietly being consumed by office rent, insurance premiums, and the estimator's time before a single tool leaves the truck.
This guide walks through how a bid price is built from the ground up - the exact same logic used by the BidFlow Bid Price Calculator. By the end, you'll know the difference between markup and margin, why contingency belongs in your bid (not your bank account), and how to sanity-check your number before you submit.
Why the overhead allocation step gets skipped - and what it costs you
When most contractors build a bid, they add up what the job will cost to deliver - materials, labor hours, equipment rental, subcontractors, permits - and then apply a flat percentage on top. That percentage is supposed to cover overhead and profit. The problem is that it's almost always set by feel ("we always do 20%") rather than by calculation, and it almost never accounts for the true cost of running the business.
Overhead includes everything that keeps the business operating regardless of whether a specific job is running: liability insurance, workers' comp, office space, vehicles, accounting software, estimating time, phone bills, and the owner's salary when they're not billing field hours. When a contractor doesn't separately calculate and allocate these costs, they get absorbed into "profit" - which means the number on the bid sheet is a fiction. The job looks profitable until the bank account says otherwise.
The fix is a two-step approach: calculate total direct costs for the job precisely, then apply an overhead percentage derived from your actual annual overhead divided by your annual revenue. That keeps the bid math honest and makes your profit margin a real number you can plan around.
Markup vs. margin: the distinction that changes every bid
These two terms describe different things, and mixing them up is a systematic error that compounds across every job. Markup is calculated on cost; margin is calculated on revenue. A 25% markup on a $100,000 cost base produces a $125,000 bid - but the margin on that bid is 20%, not 25%.
| Markup % | On $100,000 Cost Base | Bid Price | Actual Margin % |
|---|---|---|---|
| 10% | +$10,000 | $110,000 | 9.1% |
| 15% | +$15,000 | $115,000 | 13.0% |
| 20% | +$20,000 | $120,000 | 16.7% |
| 25% | +$25,000 | $125,000 | 20.0% |
| 33% | +$33,000 | $133,000 | 24.8% |
| 50% | +$50,000 | $150,000 | 33.3% |
If you're targeting a 20% profit margin, you need to apply a 25% markup on your cost base - not 20%. The BidFlow Bid Price Calculator applies profit as a percentage of the cost-plus-overhead subtotal, which is the correct method. Know which number you're using and be consistent.
How the bid price formula works - step by step with real numbers
Here's a full bid price buildup for a $280,000 commercial tenant improvement project. The numbers follow the exact calculation sequence in the BidFlow Bid Price Calculator.
1Calculate direct labor cost
FormulaLabor Cost = Labor Hours × Labor Rate
The crew will need 800 hours at a blended rate of $65/hour. Labor cost = $52,000. This is the true cost of labor - wages, not billing rate.
2Sum all direct costs
FormulaTotal Direct Costs = Materials + Labor Cost +
Equipment + Subcontractors + Permits
Materials: $95,000 | Labor: $52,000 | Equipment rental: $8,500 | Electrical sub: $34,000 | Permits: $3,200. Total direct costs = $192,700.
3Apply overhead allocation
FormulaOverhead Amount = Total Direct Costs × (Overhead %
÷ 100)
This company runs 12% overhead based on their books. $192,700 × 12% = $23,124. Subtotal after overhead: $215,824. This is where most underbid contractors lose money - they skip this number entirely.
4Add profit
FormulaProfit Amount = (Total Direct Costs + Overhead) ×
(Profit % ÷ 100)
Targeting 15% profit on the subtotal: $215,824 × 15% = $32,374. Subtotal with profit: $248,198. This is the number you'd price at with zero contingency.
5Add contingency
FormulaContingency Amount = (Subtotal with Profit) ×
(Contingency % ÷ 100)
Total Bid = Subtotal with Profit + Contingency Amount
A 5% contingency on an interior commercial job covers unknown conditions, scope creep, and subcontractor change orders. $248,198 × 5% = $12,410. Total bid price: $260,608. The contingency isn't extra profit - it's insurance against the job going sideways in predictable ways.
Bid price buildup: the complete picture
| Line Item | Amount | Notes |
|---|---|---|
| Materials | $95,000 | Quoted from suppliers |
| Labor (800 hrs × $65) | $52,000 | Blended crew rate |
| Equipment rental | $8,500 | Lifts, compressors |
| Subcontractors | $34,000 | Electrical |
| Permits | $3,200 | City fee schedule |
| Total Direct Costs | $192,700 | |
| Overhead (12%) | $23,124 | Applied to direct costs |
| Subtotal | $215,824 | |
| Profit (15%) | $32,374 | Applied to subtotal |
| Contingency (5%) | $12,410 | Applied to subtotal + profit |
| Total Bid Price | $260,608 |
Industry benchmarks for overhead, profit, and contingency
These ranges reflect what's typical across different segments of the construction industry. Your actual overhead percentage should come from your own books - but these benchmarks tell you whether you're in the right neighborhood.
| Metric | Low | Typical | High |
|---|---|---|---|
| Overhead % (small GC) | 8% | 12–18% | 25%+ |
| Overhead % (specialty sub) | 6% | 10–15% | 20% |
| Net profit target | 5% | 8–15% | 20%+ |
| Contingency (known scope) | 2% | 3–5% | 7% |
| Contingency (complex/unknown) | 5% | 7–10% | 15% |
If your overhead percentage is below 8% and you have employees, a vehicle, and insurance, your overhead number is wrong - not low. Audit it annually. Revenue grows faster than overhead for most contractors, so the percentage tends to drop over time as volume increases. The BidFlow Bid Price Calculator lets you adjust all three percentages independently so you can model different scenarios before you commit to a number.
One final discipline: don't shade your contingency down to win work. Contingency exists because jobs reliably produce surprises. A contractor who consistently underbids contingency will consistently find that their "profit" disappears into change orders they absorb rather than bill. Price the job correctly, then compete on value and execution - not on shaving safety margins.
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