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Your planned budget before adding a buffer for the unexpected.
This should be your best estimate of materials + labor + fees, before any safety margin.
The extra buffer to add for unexpected issues.
10-15% is common for a straightforward, well-scoped project; older homes, structural work, or projects with unknowns behind walls often warrant 20-25% or more.
Total budget with contingency
$23,000
Contingency is a planning buffer, not a guarantee — projects that uncover major surprises (structural damage, code-required upgrades) can still exceed even a generous contingency.
- Contingency amount
- $3,000
They open the calculator with your figures already in it
Project Contingency Calculator: 23,000 $ (total recommended budget) — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
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How this was calculated
Formula source(s)
- Total budget with contingency = base budget x (1 + contingency percent / 100); 10-20% is a commonly recommended contingency range for renovation projects
Inputs used
- Base Project Budget
- 20000
- Contingency (%)
- 15
Intermediate steps
- Contingency amount
- $3,000
Confidence note: Contingency is a planning buffer, not a guarantee — projects that uncover major surprises (structural damage, code-required upgrades) can still exceed even a generous contingency.
What this calculation does not cover
- The percentage is applied to the base budget as one flat multiplier, so every dollar of the job is treated as carrying identical risk. A $20,000 kitchen made up of $14,000 of fixed-price cabinetry already on order and $6,000 of demolition into an unknown wall gets the same $3,000 buffer at 15% as one that is speculative end to end. Where the risk sits in a single part of the scope, size a buffer against that part and add it to the rest rather than smearing one rate across the total.
- Nothing in the arithmetic is a fixed amount: the buffer is purely proportional, so it shrinks with the budget while many of the surprises it is meant to absorb do not. A failed inspection, half a day of extra excavation or an emergency call-out costs roughly the same on a $3,000 job as on a $300,000 one, yet 15% sets aside $450 on the first and $45,000 on the second. Small jobs are the ones a percentage rule quietly under-buffers.
- Whatever is missing from the base figure stays missing from the answer. The base budget is read as a single opaque number, so if permits, disposal, delivery charges or temporary accommodation were never counted in it, a 15% buffer on that total does not fund them — it scales an incomplete estimate rather than completing it.
- The output is a lump sum with no timing in it. No term asks when the money is drawn or how long ago the base was priced, so a buffer taken on a year-old estimate is a percentage of a stale number. Re-running the figure part-way through a job would need the remaining scope and the buffer already consumed, and neither is tracked here.
- The percent field accepts whole numbers from 5 to 50 and the base accepts $100 to $2,000,000; those are input bounds, not guidance about where your job belongs. The commonly cited 10-20% range is a general renovation figure, and nothing in the calculation weighs building age, how much structural work is involved, or how firm your quotes are to place you within it.
Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.
Sources checked 2026-09-05 · in the site-wide review of 2026-09-06 · v1.0.1
Regulatory standards & verification citations1
- Total budget with contingency = base budget x (1 + contingency percent / 100); 10-20% is a commonly recommended contingency range for renovation projects
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