An estimate app for contractors,
built around what an estimate needs.
A contractor's estimate has two jobs: win the work, and hold up months later when a client asks why the final bill doesn't match what was promised. That second job is the one most estimate apps for contractors quietly skip, tracking a price without tracking a licensed, itemized, dated document a client actually signed. It is also the same test that decides whether the wider category of field service apps earns its keep once a job moves past the estimate stage.
This page covers what a legally sound estimate needs to include, how markup and margin actually differ (they are not the same number, and mixing them up quietly eats your profit), and how to think about building an estimate app around your own trade instead of a generic template.
See what an estimate needs to includeThe short version
Ten fields, and a price that means what it says.
A contractor estimate needs your business name and license number, the client and job site, a written scope of work, itemized materials and labor, a total price, a payment schedule, start and completion dates, an expiration date, a change order process, and signatures. Separately, know your markup from your margin: markup is calculated on cost, margin is calculated on price, and they are never the same number. The rest of this page walks through both, with a real state law as an example and a calculator you can try.
Quick facts
The numbers behind this page.
Four figures worth knowing before you write your next estimate, each one covered in more detail further down.
$1,000 or 10%
Whichever is less — California's cap on a home improvement downpayment
16.7%
The real margin a 20% markup produces, not 20%
3–7%
Typical net profit margin across the construction industry
10
Fields a contractor estimate needs to be legally sound
The difference
A guess vs. a real estimate.
Both can look like a single number on a page. The difference shows up later, when a client pushes back on the bill and one of these holds up.
A rough guess
- A single number, no breakdown of labor vs. materials
- No expiration date, so the price is good forever until it suddenly isn't
- Extra work gets added verbally, then shows up on the final bill
- No signature, so it's a conversation, not a document
A legally sound estimate
- Itemized labor and materials, priced separately
- An expiration date on the price you quoted
- A written change order, signed before extra work starts
- Signature lines for both the contractor and the client
What to include
What a contractor estimate needs to include.
Requirements vary by state, but the base fields that show up across a painter's, a roofer's, and a general contractor's estimate are the same:
- Your business name, address, and contractor license number
- The client's name and the exact job site address
- A written scope of work, not just a price
- Itemized materials and labor, priced separately
- A total price, with any financing charges broken out
- A payment schedule tied to specific stages of the work
- Approximate start and completion dates
- An expiration date, so the price isn't open-ended
- A change order process for anything added after signing
- Signature lines for both the contractor and the client
A real example: California's home improvement contract law
Some states don't leave this list to convention. California's Business and Professions Code Section 7159 requires a written, signed home improvement contract that includes the contractor's name, address, and license number, a description of the work and materials, the total price with any finance charges shown separately, a downpayment that can't exceed $1,000 or 10% of the contract price (whichever is less), a schedule of progress payments tied to specific work, approximate start and completion dates, and required notices covering mechanics liens and the right to cancel. Extra work has its own rule: a change order has to be a fixed-price document, in writing and signed by both sides, before that extra work begins. Read Section 7159 in full . If you build in a different state, the exact numbers will differ, but the shape, a signed price, a payment schedule tied to real work, and a written step before anything changes, is the pattern to copy.
Try it
Does your estimate template have this?
Check off what your current estimate already includes, whether that's a PDF template, a generic invoicing app, or a pad of paper.
0 of 10 · Start here — none of this is on the template yet.
Change orders
Does this change need paperwork?
Not every mid-job request is new work, and not every new request needs a signed document. The line between them is what a change order process, like the one California's Section 7159 requires, is actually for.
Try it
Does this need a signed change order?
A client just asked for something extra mid-job. Answer what applies to see whether it needs paperwork before you touch it.
Verdict
Answer the questions above to see whether you need a change order.
Markup vs. margin
Markup and margin are not the same number.
Markup is calculated on cost: job price divided by direct cost. Margin is calculated on price: gross profit divided by job price. Because the selling price is always bigger than the cost, margin is always the smaller percentage of the two for the same job. A contractor who applies a 20% markup thinking it will produce a 20% margin actually nets a 16.7% margin, roughly 3 points of profit quietly missing on every job.
Try it
What price hits your target margin?
Enter your direct job cost and the profit margin you want, not the markup. This uses the same formulas contractors use to price a job: markup is on cost, margin is on price.
Price to quote
$10,000
That's a markup of
25.0%
Gross profit
$2,000
Margin to markup, converted
If you know the margin you want, here is the markup that actually produces it, using markup = margin ÷ (1 − margin):
| Target margin | Markup you need to charge |
|---|---|
| 10% | 11.11% |
| 15% | 17.65% |
| 20% | 25.00% |
| 25% | 33.33% |
| 30% | 42.86% |
| 35% | 53.85% |
| 40% | 66.67% |
| 45% | 81.82% |
| 50% | 100.00% |
Formulas per Procore's construction markup and margin guide. The published construction industry average net profit margin runs roughly 3–7%, which is a useful sanity check against whatever margin your estimate app is quietly assuming.
Terminology
Estimate, quote, bid, or invoice?
The four get used interchangeably, but each one implies a different amount of price certainty and a different point in the job. Calling a document an "estimate" when it is really a fixed, signed quote is how a client ends up surprised.
| Term | Price certainty | Typically used for | Legally binding? |
|---|---|---|---|
| Estimate | Approximate, expected to shift once real conditions are known | Early budgeting, before the scope is fully locked | Not on its own |
| Quote | Fixed once accepted, for a clearly defined scope | Jobs with a bounded, well-understood scope | Yes, once signed |
| Bid | Fixed, submitted competitively against other contractors | Public projects and larger jobs put out to bid | Yes, once awarded and signed |
| Invoice | Final, reflects the work actually completed | Billing once work has started or finished | Yes, a payment request under a contract already in force |
An estimate app that only stores one of these blurs the line between them. It also matters what happens after the estimate is accepted: if your team needs a running, timestamped record of what actually happened on site each day, that's a app for construction daily report work, a different tool doing a different job than the estimate itself.
Picking a tool
The best estimate and invoice app for contractors.
There isn't one best estimate app for contractors, there is a best fit for how your trade actually prices a job. An HVAC contractor pricing equipment and refrigerant looks different from a painter pricing square footage, which is the same reason a generic template stretches thin fast; a trade-specific build, like an hvac service app, can bake the fields a template can't anticipate straight into the estimate.
| Approach | Itemized line items | Becomes an invoice automatically | Tracks markup & margin | Who maintains it |
|---|---|---|---|---|
| Paper estimate pad | manual | No | No | you, by hand |
| Spreadsheet template | Yes | No | only if you build the formula | you, and it drifts |
| Generic invoicing app | basic | Yes | No | the vendor |
| Dedicated estimate & invoice platform | Yes | Yes | Yes | the vendor, locked to their schema |
| Custom-built estimate app | Yes | Yes | Yes | whatever your process needs |
Dedicated estimate and invoice platforms are genuinely fast to start with, scheduling, dispatch, and payments already wired together. The tradeoff is that you're working inside their fields and paying per seat for features your trade may not use. The gap they leave is whatever field or workflow doesn't fit their schema, which is exactly what a custom-built estimate app is for.
Free vs. paid
Is there a free estimate app for contractors?
For a single contractor kicking the tires, yes. Most invoicing and field service apps offer a free tier for estimates, but they cap it by the number of estimates, clients, or users a month, and the parts most useful here, itemized templates, markup and margin math, and turning an accepted estimate into an invoice with one tap, are usually the first things reserved for a paid plan. Once estimates are going out every week, budget for a real tool rather than stretching a free tier past what it was built for. Even a build-it-yourself platform like Newly starts at $25 a month, and dedicated estimate and invoice platforms typically run well past that per seat.
Building your own
An estimate app that fits your trade.
The honest reason to build your own estimate app instead of buying one off the shelf usually isn't cost, it's fit. A trade whose line items, change order steps, or sign-off chain don't match a vendor's schema ends up either bending its process to the software or bending the software until it breaks. That gap, a pricing process no off-the-shelf tool quite fits, is what Newly is for: describe the estimate you actually build, the fields, the markup rules, the signatures, and it builds a real native app around your process instead of the vendor's.
The fields and the change order rules are worth nailing down on paper first, since they're cheap to change before anything is built. Actually collecting a deposit or a progress payment once an estimate is signed is a separate decision, and it comes down to adding payments and in-app purchases, which is worth understanding once the estimate itself is locked down.
Sources
Where the specifics came from.
Two things on this page come from a primary source rather than general industry consensus:
FAQ
Estimate apps for contractors, answered.
At minimum: your business name, address, and license number, the client's name and job site address, a written scope of work, itemized materials and labor, a total price, a payment schedule, approximate start and completion dates, an expiration date, and signature lines. Many states require most of this by law for home improvement work above a set dollar amount. California's Business and Professions Code Section 7159, for example, requires a written contract with the price, a payment schedule tied to specific work, start and completion dates, and a signed change order for any extra work before it begins.
Start with the fields, not the form.
Get the estimate fields and the markup right on paper first, then build the app around them in Newly.