AP Days

The formula, and then the real question

AP Days = (What you owe suppliers ÷ What you buy from suppliers in a year) × 365

The textbook says to put cost of goods sold on the bottom. We do not, and the reason matters.

Your COGS includes the people who make the thing. Direct labor, contractors, the crew. You cannot ask your team for net 30. Payroll is due Friday whether or not anything else in your life is going well. Dropping payroll into the denominator of a number that measures supplier financing makes the number smaller and tells you nothing you can act on.

So use the line that answers a plain question: in a year, how much do you buy from other companies who send you an invoice? Materials, subcontracted work, freight, parts, the services you resell. If your books do not break that out cleanly, your accountant can pull it in about 10 minutes, and it is worth asking for.

Run the textbook version too if you are handing a number to a lender or a peer group, because that is the one they will compare you against. You may see it called days payable outstanding, DPO, or creditor days. Both versions are fine. Only one of them tells you whether to pick up the phone.

Now the version that matters, because the formula is not the lesson:

Did you ever ask?

That is most of the number. Net 30 is on your invoices because it was on the last invoice, and on the one before that, going back to a decision nobody in your company was present for.

The half of the cycle nobody negotiates

Watch what a good founder does with the money coming in. They rewrite the agreement. They add autopay. They argue for net 21 and mean it. They will spend a year of real effort pulling receivables forward, because every day of it is cash they already earned.

Then an invoice arrives that says net 30, and they pay it on day 30 without a thought.

Both ends move the same bracket. Look at the cash conversion cycle and you can see why AP subtracts: those are days somebody else carried the load and you did not. A day is a day.

But the two ends do not cost the same to move. Shortening AR means renegotiating with a customer who can leave. Lengthening AP means asking a supplier who wants to keep selling to you. One of those conversations is genuinely risky. The other is a phone call, and it is the one nobody makes.

If you buy $3M a year from suppliers, one day of AP is about $8,200. Twenty days of terms you never asked for is roughly $164,000 sitting in somebody else's account instead of yours, permanently, for as long as you keep buying.

Terms are part of price, and your supplier knows it

There is a story founders tell themselves here, and it is doing real damage: that a vendor who extends terms is doing them a kindness.

They are not. They are competing for your business.

A supplier who will not move a nickel on price will frequently move 15 days on terms. Here is why, and it is not generosity.

Ask for a lower price and they know exactly what it costs them. It comes straight off their profit, on a line their boss reads every month. The answer is usually no, and it is an informed no.

Ask for 15 more days and they check whether they can live without the money for 15 days, decide they probably can, and say yes.

What it actually cost them is 15 days of their own money sitting somewhere else, which is worth precisely what those days are worth to you. Same math, opposite direction. They mostly never run it. Their own AP days is not on anybody's dashboard, no bonus depends on it, and the person approving your request is not the person who feels it.

We are not going to pretend that is a tragedy. Nobody on the other end of that call has read this page. That is exactly why the cheaper concession is the one available to you, and why it stays available.

The fair version: when one of your customers asks you for terms, you will know what you are handing over. Most founders never put terms on the table at all, buy at list price on default terms, and call it the market rate.

Which changes how you ask. Not "can I have more time," which is a request for sympathy and invites a no. Try the version that is true: you are reviewing suppliers this year, and you want to know their best terms at volume. That is a purchasing conversation, and purchasing conversations have room in them.

When paying slower is the expensive choice

Here is where AP stops mirroring AR, and it is why lever 8 in the 10 levers reads pay strategically and not pay slower. Three ways stretching costs more than it holds.

1. The early-pay discount you walked past. Terms like 2/10 net 30 mean 2% off if you pay within 10 days instead of 30. Skip it and you have paid 2% to hold your money 20 extra days, which annualizes to about 37%. That is credit card money, quietly, on an invoice. If the cash is there, take the discount. If it is not, at least price the delay honestly before you choose it.

2. Conversion to cash on delivery. This is the one that actually bites, and almost nobody sees it coming. Push a supplier past their patience and they do not sue you. They put you on COD. You have just converted 30 days of free financing into cash up front, and if that supplier feeds a job you are halfway through, your gap did not narrow, it doubled. Stretching the vendor you need most is the most expensive move on this page.

3. The paperwork you signed and forgot. Trade credit reporting, personal guarantees, and industry-specific escalation. In construction supply, lien filing typically begins at 60 days past due rather than at 30, which cuts both directions: there is more room in practice than the invoice implies, and there is a hard stop out there that is not a negotiation.

A high number is not automatically a good number

AP days went up. Good news or bad news?

You cannot tell, and that is the important part. It is either terms you negotiated or bills you did not pay, and those are opposite conditions that produce an identical number. Any lender reading your statements knows this, which is why they ask, and why your answer matters more than the figure.

The test is one question: did the number move because you asked, or because you could not? One of those is a lever. The other is a symptom wearing a lever's clothing.

Pay on purpose

The goal was never a bigger number.

Some suppliers you pay early, deliberately, because it buys you something worth more than the days. The one who moves your order to the front of the queue when the schedule gets ugly. The one whose discount beats your actual cost of capital. The small one for whom your invoice is a real part of their month, and who will remember which way you went when it was tight.

That is what paying strategically means. Some terms are worth reopening, some relationships are worth funding, and knowing the difference is the entire skill.

If you are reading this because the money genuinely is not there this month, that is a different and more urgent conversation, and we wrote it down: can I ask my vendors for more time to pay.

Which suppliers to pay early, which terms to reopen, and how far you can stretch before it costs more than it holds is a reading of one business. That is what a CFO Huddle™ is for.