A-du's Permit Fee Calculator: What Each Line Item Really Means

Photo: LADBS homeowner resources, via Los Angeles Department of Building and Safety.

Run the same size ADU through A-du's permit fee calculator in Los Angeles and in New York City and you get two very different receipts. A 750 square foot detached ADU in the City of Los Angeles comes back with 17 line items totaling $4,899.83. An 800 square foot attached ADU in New York City comes back with two line items totaling $1,591.25. Neither number is an estimate we made up for this post. Both come straight out of the live tool, and every line carries the statute or code section behind it.

Two calculators, one very different code book each

A-du runs two separate permit fee tools: a California version and a New York City version. Underneath, California is modeled as twelve separate jurisdictions: the City of Los Angeles, unincorporated LA County, and ten incorporated cities including Pasadena, Glendale, Long Beach, Burbank, Santa Monica, Culver City, Beverly Hills, Inglewood, West Hollywood, and Manhattan Beach. Each has its own fee schedule, because each runs its own building department.

New York City is modeled as exactly one jurisdiction, regardless of borough. That is not a shortcut we took to save engineering time. The Department of Buildings is a single citywide permitting authority, so a Bronx rowhouse and a Staten Island bungalow file under the same fee structure. What actually varies project to project in NYC is the zoning district pulled from the city's PLUTO dataset, not which of the five boroughs the lot sits in.

What a 750 square foot Los Angeles ADU actually costs to permit

For a 750 square foot detached ADU with one bedroom and one bath, the calculator prices construction at $230 per square foot (the 2026 ICC Building Valuation Data figure LADBS publishes for Type V-B, occupancy R-3, adjusted every February), for a construction valuation of $172,500. From there the fees stack:

The building permit fee runs $2,094.75 under LAMC 91.107 Table 1-A, a sliding bracket tied to valuation. The plan check fee adds another $1,885.28, set by LAMC 91.107.6 at a flat 90 percent of the building permit fee. Electrical, plumbing, and mechanical sub-permits add $196, $230, and $170 respectively, each its own code section (LAMC 93.0205, 94.0203, 95.115) with its own per-fixture math. Records management is a flat $160. Construction tax under LAMC 21.10 is $150. Two small state pass-through surcharges (SB 1473 and the Building Standards Commission surcharge) add $6.90 each.

Then come the waivers, and this is the part worth sitting with if you are a first-time ADU homeowner in California. The impact fee line reads $0, waived under SB 543 for any ADU at or below 750 square feet. The school district development fee reads $0 too, permanently waived for ADUs under California Education Code 17620. Sewer, water, and electrical connection fees all zero out because the calculator assumes you are tying into existing service, which most single-family retrofits do. Skip any of those assumptions, say you need a new electrical panel or a new sewer lateral, and those line items reappear.

What the same math looks like in New York City

Run an 800 square foot attached ADU with one bedroom and one bath through the NYC calculator and construction prices out at $350 per square foot under NYC Administrative Code Section 28-112.3, for a valuation of $280,000. The DOB work permit fee for one, two, and three family alteration work is $130 for the first $5,000 of that valuation, plus $5.15 for every $1,000 above it, which nets out to $1,546.25. Add a flat $45 records management fee under 1 RCNY Section 101-03 and the total comes to $1,591.25.

That is the entire schedule. No separate sub-permits broken out for electrical, plumbing, or mechanical work. No construction tax. No impact fee or school fee line, waived or otherwise, because New York City's ADU financing and legalization programs operate through HPD grants rather than a fee-waiver statute. The DOB folds trade work into the single alteration permit fee instead of pricing each trade separately the way LADBS does. Fewer line items is not a sign the NYC process is cheaper end to end. It just means the fee schedule bundles differently, and a homeowner comparing a $4,899.83 LA quote to a $1,591.25 NYC quote is not comparing equivalent scopes of review.

Why the gap between the two tools matters

If you are an A-du curious homeowner trying to decide whether a permit fee estimate is trustworthy, the honest answer is that it is only as good as the code sections behind it. That is why every line item in both calculators links back to a specific statute, whether that is SB 543's fee exemption for small California ADUs, the California Health and Safety Code sections behind the state surcharges, or NYC Admin Code 28-112.2 and 1 RCNY 101-03 behind the DOB fee. You can check our math against the primary source yourself, which is the whole point of publishing it this way instead of a flat number with no citation trail.

For a homeowner building in Los Angeles, Pasadena, or one of the other ten incorporated cities the tool supports, that also means the estimate updates when the underlying ordinance changes, the way the impact fee line dropped to zero the moment SB 543 took effect. For a New York City homeowner, it means watching one fee schedule instead of five separate borough offices, since DOB pricing does not vary by borough even though inspections and industry meetings are scheduled at each borough office separately.

If you are pricing out a build in either market, A-du's permit fee calculator is a reasonable place to start before you talk to a contractor, precisely because every number on the page traces back to a code section you can read for yourself.