Estimating contingency: how much to carry and where it belongs
No drawing set is perfect, and no job goes exactly to plan. Contingency is the money you carry for the risks you can see but can't price exactly. Carry too little and one surprise eats your profit. Carry too much and you lose the bid. Here's a practical way to think about it.
- Contingency covers known risks with unknown costs. It is not extra profit.
- Allowances and escalation are different from contingency and should be listed separately.
- Size contingency by the quality of the documents and the risk on the job, not by habit.
Contingency vs. allowances vs. escalation
- Contingency: money for scope gaps, coordination problems, quantity errors and conditions you can't fully see at bid time.
- Allowances: a set amount for items the owner hasn't chosen yet (for example, a fixture or finish). Allowances should be clearly listed, with the understanding that the final cost will be adjusted up or down.
- Escalation: money for expected material and labor price increases between bid day and when the work happens.
Keep them separate in your estimate. Mixing them hides risk and makes it harder to explain your number.
What drives how much you carry
- Document quality: 50% design drawings need much more contingency than a complete, coordinated set.
- Existing conditions: renovation and occupied buildings hide surprises behind every wall.
- Schedule: compressed schedules add overtime and stacking of trades.
- Contract type: on a lump-sum job, you own the risk. On cost-plus or GMP work, contingency is usually shown openly and shared.
- Your own data: look at your last ten jobs. How far off was your estimate, and why?
A simple risk-based approach
- List the specific risks (for example, "ceiling heights not shown on sections").
- Estimate the cost if each one happens, and a rough chance it will.
- Multiply and add them up. That's a reasoned contingency you can defend.
- Compare it to your historical percentage as a sanity check.
Where to show it
On a lump-sum bid, contingency is usually built into your numbers rather than shown as a line item, because an owner may try to cut a visible line. On negotiated work, a clearly labeled contingency with rules for how it's used builds trust. Either way, track it internally so you can see how much you used.
Related: markup vs. margin · waste factors in takeoff · bid day checklist.
Published October 26, 2026. We do not use affiliate links on this page; see our Affiliate Disclosure.