Cost · 5 min read
An empty hour does not cost you your average production. It costs you that production minus the lab, supplies and card fees you would have spent to earn it, because everything else gets paid either way.
An empty chair costs you the margin the hour would have earned, not the hour's production. Rent, salaries, leases and software are paid whether the schedule is full or not. The only costs an open hour saves you are the ones that rise with the work itself: lab, clinical supplies and card processing fees. In the worked example below, that is about $399 an hour for the doctor and $208 for hygiene. You can compute your own from last month's P&L and the hours patients were actually booked.
That number matters more this quarter than last. In the ADA Health Policy Institute's Q3 2026 survey, sent to dentists on September 14, 38% of dentists said they were not busy enough and could have treated more patients, up from 26% in Q2 (ADA HPI, State of the U.S. Dental Economy, Q3 2026). If your schedule has holes in it, you are not alone.
Most of what a dental practice spends is committed before the first patient arrives. The lease, the front desk, the assistants, the hygienist's scheduled hours, the equipment loan, the software subscriptions, insurance and the marketing contract all cost the same in a month with ten open hours as in a month with none.
That is why an empty hour feels free and is not. Nothing new gets spent, so nothing shows up on the P&L as a cost. What shows up instead, a month later, is production that never happened sitting against the same expenses, and an overhead percentage that went up with no new spending behind it.
Take one month of your profit and loss statement and sort every expense line into one of two piles.
| Expense line | Variable or fixed |
|---|---|
| Lab fees | Variable: rises and falls with the dentistry |
| Clinical supplies | Variable |
| Credit card processing fees | Variable |
| Team payroll, including scheduled hygiene hours | Fixed: paid whether the chair is full or empty |
| Rent and facility costs | Fixed |
| Equipment leases, loan interest and depreciation | Fixed |
| Practice software, insurance, professional fees and marketing | Fixed |
Lab and supplies are the bulk of the variable pile. Together they should run 10% to 14% of net production, the sum of the 5% to 7% ranges for each in the 2024 ADCPA and NSCHBC Benchmark Report (our post on clinical cost covers the range), and card fees add a little more. Almost everything else is fixed over a month. Payroll is the judgment call: a hygienist paid for the hours on the schedule is a fixed cost for those hours, even if nobody is booked into them. Sending someone home early turns a little of it variable, at a cost of its own.
Rent belongs in the fixed pile, but it carries no benchmark. A lease reflects your building and your market, not your dentistry, so read it against your own history, as our occupancy post explains.
Here is an illustrative practice, one doctor and one hygienist, open 16 days a month for eight hours, or 128 hours. Assume every one of them was booked.
| Line | Month |
|---|---|
| Net production | $90,000 |
| Variable costs: lab $5,400, supplies $5,400, card fees $1,500 | $12,300 |
| Fixed costs: payroll $25,000, facility $7,000, equipment $3,000, software, insurance and fees $5,500, marketing $2,000 | $42,500 |
| Fixed cost per open hour ($42,500 ÷ 128) | $332 |
| Margin per open hour, production minus variable costs, ÷ 128 | $607 |
The two hourly numbers answer different questions. The $332 is what each open hour costs to keep the doors open. You pay it either way, so it is not what an empty hour costs you. The $607 is what one clock hour of the whole practice, both chairs together, adds after its own costs. An empty hour in one chair takes away part of it, and the next section splits it.
The same practice breaks even at about $49,200 of monthly production, which is $42,500 of fixed cost divided by the 86% of each production dollar left after variable costs. An empty doctor hour takes $478 of production and $399 of profit out of the month. An empty hygiene hour takes $225 and $208.
This practice's staff payroll is 28% of net production and its total overhead 61%, both inside healthy ranges. Our free Dental Practice Benchmark Scorecard checks yours against those ranges in about two minutes.
The $607 is both chairs together. The two chairs behind it are not worth the same.
In the same practice, hygiene produces 32% of net production, $28,800 a month, inside the 30% to 40% share the ADCPA and NSCHBC report treats as healthy. Its variable cost is light, mostly supplies and card fees on that production, about $2,200. Doctor production is the other $61,200, and it carries all of the lab, most of the supplies and its share of card fees, about $10,100. Thirteen empty hours is about 10% of the 128.
| Chair | Margin per hour | 13 empty hours a month | Over a year |
|---|---|---|---|
| Doctor | $399 | about $5,200 | about $62,000 |
| Hygiene | $208 | about $2,700 | about $32,000 |
An empty doctor hour costs this practice roughly twice what an empty hygiene hour does. That does not settle which opening to fill first. A hygiene visit also leads to the exam and to treatment the doctor does later, and none of that shows in the $208. The same arithmetic explains why a hygiene column with holes in it drags down the hygiene productivity ratio directly: the hygienist's hour is paid in full, and the empty hour produces nothing against it.
These are averages. A last-minute fill may be a shorter or lighter appointment than the one that cancelled, so the hour you save is often worth less than the full margin.
Use it to price decisions.
If a short-notice list, a confirmation routine or an extra hour of front desk time fills four doctor hours a month, it is worth about $1,600 a month to this practice. That sets the ceiling on what it is worth paying for.
It also changes how you look at a discounted appointment. An hour filled at a lower fee still beats an empty one as long as the fee covers its own lab and supplies, because the fixed cost is already paid. The risk is that the discounted patient takes an hour a full-fee patient would have filled, which is a question about how full your schedule really is.
And it tells you when to stop cutting. A practice with soft production often looks for expenses to trim. If the problem is open hours, cancelling a $500 subscription saves $500 a month. Filling five more doctor hours a month earns about $2,000. Look at the schedule before the spending.
P.S. Reciprocity Accounting closes dental practice books by the 10th of every month, so last month's numbers are in front of you while you can still act on them. See how we can help your practice.
The production that hour would have done, minus its lab, supplies and card fees. In our illustrative one-doctor practice that is about $399 an hour for the doctor and $208 for hygiene. Your own number comes from your P&L divided by the hours patients were actually booked, not the hours you were open.
Because an empty hour does save you a little: the lab, supplies and card fees you would have spent to do the work. Production per hour overstates the loss by that amount.
For the hours on the schedule, fixed. You pay the scheduled hour whether or not anyone is booked into it.
Sort one month of your P&L into costs that rise with the dentistry (lab, supplies, card fees) and costs that do not. Everything in the second pile is fixed over a month.
In the ADA Health Policy Institute's Q3 2026 survey, 38% of dentists said they were not busy enough and could have treated more patients, up from 26% in Q2 2026.