Ontario Construction Estimating Services

Ontario, California. San Bernardino County, west end of the Inland Empire, wrapped around Ontario International Airport. Not Ontario, Canada — if you searched “Ontario construction cost” and got Canadian dollars and Canadian code, that’s the wrong Ontario and this is the right page.

Here’s the thing about bidding work here. Ontario runs its own building department. It is not a county plan-check city. That means the fee math is Ontario’s fee math, and Ontario’s fee math is heavier than most people budget for.

Plan check in Ontario is 80% of the permit fee. Not a flat rate. Not a couple hundred bucks. Eighty percent, on top. On a $500,001 job the permit fee alone starts at $3,880.50 and climbs $5.70 for every additional $1,000 of valuation. Add the plan check and you’re already past $7,000 before anybody pulls a tape measure.

Want it faster? That costs too. Ontario’s expedited plan check runs on a sliding scale — 50% extra under $1 million, 40% from $1M to $5M, 30% from $5M to $10M, and it keeps stepping down to 10% over $20 million. Small jobs pay the most to jump the line. That’s backwards from what most contractors assume.

And every correction cycle after the first has a meter on it. $143.36 an hour for additional plan review. If your set goes back three times, you’re going to pay for the privilege in real dollars, not just calendar.

None of that shows up in a national square-foot number. It shows up in ours, because we read the fee schedule.

1. The warehouse rules changed, and they changed the site plan. AB 98 took effect January 1, 2026, and Ontario sits inside the Riverside–San Bernardino Warehouse Concentration Region, which gets the strict tier. Loading bays have to sit at least 500 feet from the nearest sensitive receptor. Buffers go to 100 feet. Truck entry gates need 50 feet of stacking depth inside the property line. That’s not a code note. That’s acreage, paving, screen wall and gate hardware that either got drawn or didn’t.

2. WAIRE. South Coast AQMD Rule 2305 catches warehouses at 100,000 square feet and up, in three phases — 250,000+ first, then 150,000, then 100,000. You can buy out the obligation at $1,000 per WAIRE point. Owners find out about this after the pro forma is locked. Ask early.

3. Airport compatibility review. ONT is inside the city. Projects in the airport influence area go through the Ontario International Airport Inter-Agency Collaborative, which the City of Ontario Planning Department runs, and which also covers Chino, Fontana, Montclair, Rancho Cucamonga and Upland. It’s a real review step with a real calendar cost.

4. The small line items that add up. Commercial earthquake fee is valuation times 0.00021. On-site sewer assessment is $6,955 per dwelling unit. Dust control is $250. Grading plan review starts at $1,474 for rough, $1,833 for precise. Microfilming is $1.50 a plan page — on a 90-sheet industrial set that’s $135 nobody carried. Individually they’re nothing. Together they’re a change order you didn’t need.

One more, free: warehouse electrical permits in Ontario are charged at $0.012 a square foot for the first 50,000 feet, against $0.12 for general commercial. That’s a tenfold difference. If you’re pricing an industrial shell off a commercial template, you’re going to be ten times high on that line and you’ll never know why the number felt wrong.

We’re not going to show you a stock photo of a hard hat. Here are real estimates we produced, with the job-site zip printed inside each one. Open them. They’re on this page.

Ground-up and full-scope work:

1. Ontario 5U — 91762 — $2.8M. Fourteen pages, Division 1 through Division 16. 2. Diamond Bar Plaza — 91765 — $2.4M. 3. Autozone Fontana Project — 92335 — $862K. 4. Corona Senior Center — 92882 — $319K.

Retail and restaurant tenants:

1. Dollar Tree Colton — 92324 — $134K. 2. Americas Best Contact’s & Eyeglasses, Upland — 91786 — $105K. 3. Five Below Colton — 92324 — $22K. 4. ONO ONTARIO HAWAIIAN BBQ — 91764 — $16K.

Tenant improvements and renovations:

1. LA Fitness Corona — 92882 — $1M. A full interior fit-out, metal framing through paint. 2. 4978 Walnut Ave Renovation, Chino — 91710 — $354K. 3. AMC Ontario 30 Dolby Remodel — 91764 — $42K. 4. Fabletics, Ontario Mills — 91764 — $7K.

Every one of those is a document, not a claim. The dates are redacted. Nothing else is.

Ontario has four zip codes: 91758, 91761, 91762 and 91764. We’ve got priced work sitting in two of them.

91764 — Ontario Mills, Ontario Center, the I-10/I-15 node. Ontario Mills opened in 1996 and it’s still California’s largest outlet and value retail destination. We’ve priced three jobs in that zip: the AMC Ontario 30 Dolby remodel, ONO Ontario Hawaiian BBQ, and a Fabletics build at Ontario Mills itself. Mall landlord work has its own rhythm — night work, limited access, a landlord criteria manual that overrides the drawings. We’ve done it.

91762 — Downtown Ontario and the Euclid Avenue corridor. Ontario 5U is here, and it’s the biggest thing on this page at $2.8M across fourteen pages of trades.

91761 — the airport belt and Guasti. This is ONT and the industrial ground around it. In 2025 the airport moved 835,129 tons of air cargo, up 5.3%, and 7.1 million passengers. That cargo number is why the warehouse market here looks the way it does, and why AB 98 and Rule 2305 are line items and not footnotes.

South Ontario — Ontario Ranch. Annexed in 1999 as the New Model Colony, it’s 8,069 acres, roughly thirteen square miles, with the city planning 31 million square feet of industrial and 12 million square feet of commercial and office on top of the housing. Ontario Ranch Road, Archibald, Haven, Eucalyptus, Riverside Drive. If you’re building down there, you’re going to run into the airport overlay, the warehouse setbacks, or both.

Around the city line, we work the corridor the way a contractor here actually does. Chino at 91710. Upland at 91786. Fontana at 92335 and 92336. Colton at 92324. Over the Riverside County line into Corona at 92882, about fifteen miles out. East into Diamond Bar at 91765. Those aren’t service-area claims — every one of them has a priced job on this page behind it. And Chino, Fontana, Montclair, Rancho Cucamonga and Upland are the same cities that sit on the airport land-use body with Ontario, so it’s one market whether you draw it that way or not.

General contractors bidding hard-bid or design-build in the 909 who don’t want to keep a cost estimator on salary between pursuits.

Developers who need a real number before the pro forma goes to committee, not a per-square-foot guess off a national average.

Subs who want their own scope taken off cleanly so they’re not eating somebody else’s exclusions.

Owners and tenants doing a build-out at Ontario Mills or anywhere along Holt, Milliken or Haven who’ve been handed three bids that are half a million apart and have no idea which one is telling the truth.

What you get is a line-item estimate organized by CSI division, with quantities you can check, unit costs you can argue with, and the trades broken out so you can hand each page to the right sub. Same format as every document on this page.

If you’re bidding in Ontario and you’re working off a number somebody guessed, you’re going to find out on the job. Send us the plans. We’ll price it.

Our Ontario construction estimating services cover the whole west end — Ontario, Chino, Upland, Fontana, Colton, Rancho Cucamonga, and out to Corona.