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HVAC Accounts Receivable & DSO Calculator

The work is done, the invoice is out, and the money still isn't in the bank. Put in what you bill on account and what customers owe you right now. See how many days of billing are sitting in A/R, how much cash you'd free up by collecting faster, and what waiting costs you each year.

Runs in your browser — nothing you type is sent anywhere

Example numbers — replace with yours. The starting values are placeholders so the form isn't empty. They are not industry averages, benchmarks, or a recommended DSO.

Billing and what you're owed

Your target and your cost of money

A/R aging buckets (optional)

From your A/R aging report. Leave at 0 to skip. Days are past the due date.

Results

Days sales outstanding (DSO) —
You bill on account about —
A/R if you hit your target —
Cash freed by hitting target —
Yearly cost of carrying the extra A/R —
A/R over 60 days past due —
A/R over 90 days past due —

What this means

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The math

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What DSO is, in plain words

Days sales outstanding (DSO) is your A/R balance measured in days of billing. If you bill $2,000 a day on account and customers owe you $66,000, that's 33 days of billing sitting in other people's bank accounts. The formula:

DSO = A/R balance ÷ (revenue billed on account ÷ days in the period)

Lower is better: it means invoices turn into cash faster. Compare it with your own payment terms. If you bill net 30 and your DSO is well past 30, customers are paying late on average.

Why "on account" matters

Only count revenue you invoice and collect later — commercial work, builders, property managers, some replacements. If you add in the service calls paid by card at the door, the daily revenue goes up but A/R doesn't, and your DSO looks better than it really is. If most of your work is paid at the job, your DSO on the invoiced part is the number to watch.

Worked example

With the example numbers above: $60,000 billed on account last month, $66,000 in A/R, a 25-day target, and a 10% line of credit.

  • Revenue per day: $60,000 ÷ 30 = $2,000.
  • DSO: $66,000 ÷ $2,000 = 33 days.
  • A/R at 25 days: 25 × $2,000 = $50,000. Cash freed: $66,000 − $50,000 = $16,000, one time.
  • Carrying cost: $16,000 × 10% = $1,600 a year — about what you'd pay in interest to borrow that $16,000 on the line instead of collecting it.
  • Aging: $3,000 (61–90) + $2,000 (over 90) = $5,000 over 60 days, which is $5,000 ÷ $66,000 = 7.6% of A/R. $2,000 ÷ $66,000 = 3% is over 90 days.

How to bring DSO down

  • Collect at the job whenever you can, and take deposits on installs.
  • Invoice the same day the work is done or the milestone is reached. Every day an invoice waits to go out adds a day to DSO.
  • Work the aging report every week, oldest and biggest balances first.
  • Put terms in writing before the job, and follow up on a schedule.

Our guide HVAC Cash Flow: How to Get Paid Faster (2026) covers each of these, with a follow-up schedule for commercial invoices and how to read an A/R aging report.

Things this leaves out

  • Seasonality. One month's billing can make DSO jump. A busy month makes DSO look low; a slow month after a busy one makes it look high. Use 12 months to smooth it, and compare the same month year to year.
  • The cash freed is one-time. Collecting faster moves money into your bank once. The carrying cost is what you save each year after that.
  • Bad debt. Some old invoices may never be paid. This tool doesn't guess which ones — talk to your accountant about writing them off.
  • Retainage. Commercial retainage you can't bill yet can inflate A/R. Consider leaving it out of both A/R and revenue.

We don't quote a "typical" HVAC DSO or aging mix, because we haven't found a solid public source for it. That's what the anonymous Owner Numbers survey collects, so owners can compare against real peers.

Related tools and guides

Faster collections help, but the slow season still needs a cushion. The HVAC slow-season cash reserve calculator works out how much cash to set aside. For deposits, progress billing, invoice follow-up, and a 13-week cash forecast, read HVAC Cash Flow: How to Get Paid Faster (2026). Cash also gets stuck on your shelves and trucks. The HVAC parts inventory turnover calculator shows how much you could free by carrying less stock.