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Owner-Builder Cost Savings Calculator
What you actually keep by acting as your own GC — the builder’s fee you avoid, held apart from the value of your own hours instead of quietly added to it.
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Printed from build-your-house.com/feasibility/cost-savings-calculator — estimate only.
Methodology
How this worksheet is figured
SHEET W-01
Cash saved. Contract price × fee percentage. The build cost you enter is the all-in number a general contractor would quote you — their fee included — and the percentage is that fee's share of it. Keep the fee and your cost is the contract less the fee; the subs and suppliers still get paid exactly what they were going to get paid.
Why your labor is not added in. Your budget already carries subcontractor labor. Doing the work yourself removes that line from the budget — it does not create a second pot of savings sitting next to the fee. Adding both is how a 14% saving gets advertised as 40%. The value of your hours is on the sheet, on its own line, marked as not cash, because it is worth knowing what you are contributing even though you cannot spend it.
Fee kept, per hour you work. The fee you avoid divided by the hours you put in. This is the number to argue with: if it comes out below what you earn at work, and you would otherwise be earning it, the math is telling you something.
Cost per square foot. Your cost after the fee, divided by finished square footage — the figure you can hold up against what people in your county are actually paying. The with-a-GC number sits beside it for comparison.
What is not modeled. Builder's-risk insurance, permit and impact fees, construction-loan interest, tool rental, and re-work. Those are covered under the reality check below, and the whole-house material estimator and budget tracker are where the real numbers go once you have quotes.
Assumptions
What this sheet takes as given
ADJUST ABOVE
- Cash savedFee % × contract price
- Your costContract price − fee
- Sweat equityHours × your hourly value
- Sweat equity in the headlineExcluded
- Fee percentage cap30%
- Full-time week40 hours
- Added owner-builder costsNot modeled
The fee
What you are keeping, and what it bought
15–20% TYPICAL
General contractor fees. Most GCs charge 15–20% of total construction cost. On a $300,000 home that is $45,000–$60,000. Manage the project yourself and you keep it — which is the whole financial case for owner-building, and it is a good one.
What that fee does for you. Coordinating subcontractors, holding the schedule together, walking inspections, ordering materials on time, and overseeing quality. Every one of those becomes your job. The fee is not free money sitting on the table; it is payment for work that still has to happen.
Your labor has value too. Whether you frame walls, run trim, or paint, you are doing work that costs $30–$75 an hour to hire out. Most owner-builders contribute 400–1,000 hours. That is real value — it just shows up as a smaller budget rather than as cash in your pocket, which is why this sheet keeps it on a separate line.
Beyond the fee
The savings that do not show up in the headline
HONEST VERDICTS
Owner-builders pick up smaller savings all over the job. They are real, but they vary enough that this sheet will not put a number on them for you — here is the honest verdict on each.
- Contractor pricing on materialsPartly — supply houses, not big boxes
- Markup on subcontractor bidsAvoided
- Cost decisions made in real timeYours to make, or to blow
- Finish work GCs sub outSweat equity, not cash
- Communication overheadGone — you are the overhead
Reality check
What the savings will cost you
READ THIS TWICE
Time investment. Plan on 12–18 months from permit to move-in. Your evenings and weekends go into managing the project even if you hire out most of the labor — and the hours are not optional or reschedulable when an inspector or a concrete truck is involved.
Learning curve. You will need to learn building codes, inspection requirements, and construction sequencing. Budget time and money for mistakes and re-work; sequencing errors are the expensive kind, because they get discovered after something is covered up.
Stress factor. Managing a build is stressful in a way that is hard to price. Every decision, every delay, and every dollar is yours. Ask anyone who has done it what the last two months were like.
Opportunity cost. Consider what else those 400–1,000 hours could have gone to. The value of your labor depends entirely on what you are giving up to spend it here — which is exactly what the “value of your time” field is asking you to be honest about.
None of that makes owner-building a bad decision. It makes it a job. Take the feasibility assessment for a straight answer on whether it fits your situation, and the complete roadmap for what the sequence actually looks like.
Questions
Owner-builders ask
FAQ
How much do you actually save by being your own general contractor?
The cash you keep is the builder’s fee, and that is typically 10–20% of the contract price. On a $300,000 build at 14%, that is $42,000 — real money, and it is the number this worksheet leads with. What it is not is the 30–40% figure you see quoted online. Those numbers get there by adding the value of your own labor to the fee you avoided, which double-counts work the budget was already paying for.
Should I count my own labor as savings?
No — not as cash. Your construction budget already includes what subcontractors charge to do that work. If you frame the walls yourself, you do not pay the framer, so the savings show up as a smaller budget, not as a separate pile of money on top of the GC fee. Counting both is the single most common way owner-builder savings estimates get inflated. That is why this sheet lists the value of your hours on its own line, marked "not cash": it is real value you are contributing, but it is sweat equity, not a check you get to keep.
What does a general contractor’s fee actually pay for?
Coordinating and scheduling every subcontractor, ordering materials so they land before the crew does, walking inspections, catching bad work before it gets covered up, carrying the liability, and eating the cost when something has to be redone. Their sub relationships also mean their calls get returned first. When you keep the fee, you take on every one of those jobs — and the trades you have never met price your one-off job accordingly.
What costs go up when you owner-build?
Financing is usually the big one: fewer lenders write owner-builder construction loans, and the ones that do often want more down or charge a higher rate. Then builder’s-risk insurance you buy yourself instead of riding on a GC’s policy, re-work from mistakes a builder would not have made, tool and equipment rental, and schedule drag — every extra month is another month of construction-loan interest and, often, rent or a mortgage somewhere else. Budget a contingency that assumes you will make expensive mistakes, because you will make some.
How many hours does owner-building take?
Most owner-builders put in 400–1,000 hours across a 12–18 month build, even when they hire out nearly all the labor. That is evenings and weekends: bid packages, material orders, inspection scheduling, site visits, and the phone calls that never stop. This sheet divides the fee you keep by those hours so you can see what your time is earning — at $42,000 over 500 hours it is $84 an hour, which is the honest way to compare it against overtime at your day job.
Do owner-builders really get contractor pricing on materials?
Partly. Lumberyards and supply houses will open an account and quote you off list once they see a real project and a real permit, and that pricing beats big-box retail on lumber, trusses, windows, and doors. What you will not get is the volume tier a builder putting up thirty houses a year is on. Plan on landing between retail and builder pricing, and get three quotes on every package over a few thousand dollars.