Invoice aging calculator
List the invoices you are still owed. See them grouped by how late they are, what share of your money is past due, and which ones to chase first.
No account, no email wall. It runs entirely in your browser — nothing you type leaves it.
Total owed
$12,830
Across 5 unpaid invoices, as of 30 September 2026.
Past due
86%
$11,030 is past its due date.
Average days late
40.5
Across overdue invoices, weighted by amount, so a large late invoice counts for more.
$2,150 (16.8%) is more than 60 days past due. That is the money least likely to arrive on its own, and the place to start.
| Bucket | Invoices | Amount | Share |
|---|---|---|---|
| Current | 1 | $1,800 | 14% |
| 1–30 days | 1 | $2,480 | 19.3% |
| 31–60 days | 1 | $6,400 | 49.9% |
| 61–90 days | 1 | $950 | 7.4% |
| 90+ days | 1 | $1,200 | 9.4% |
| Invoice | Days past due | Amount |
|---|---|---|
| Northgate Cafe | 123 | $1,200 |
| Pike & Co | 72 | $950 |
| Oakline Builders | 33 | $6,400 |
| Lumen Studio | 8 | $2,480 |
| Harbor Dental | Not yet due | $1,800 |
Next steps
For the invoices at the top of the oldest-first list, the late payment email generator writes a reminder worded for how late each one is. For the bigger picture, how to read an aging report and the DSO calculator.
Questions about invoice aging
- What is an invoice aging report?
- A list of your unpaid invoices grouped by how far past their due date they are: current (not yet due), 1–30, 31–60, 61–90 and more than 90 days. The totals show how much of what you are owed is getting old, and the oldest columns are the money least likely to arrive without a push.
- How are days past due counted?
- Calendar days from the due date to the "as of" date. An invoice due on the 22nd is 8 days past due on the 30th. An invoice due on or after the "as of" date counts as current.
- What does "average days late" mean here?
- The average number of days past due across overdue invoices, weighted by amount. A $6,000 invoice 30 days late moves it more than a $200 invoice 90 days late, because that is what moves your cash.
- What should I do about each column?
- Current: check the invoice reached whoever pays it. 1–30 days: a short reminder asking when it is scheduled. 31–60: ask what is holding it up. 61–90: change the channel, call or write to finance. Over 90: decide on a payment plan, a final notice or a write-off, and act on it.
- Is my data stored anywhere?
- No. There is no signup and no server call; everything runs in your browser. The email box further down the page is optional.
Collectly does this across every invoice, on its own
You just built an aging report. Collectly does the same thing continuously for every unpaid invoice you have — reads the replies, works out why each one is unpaid, estimates when it will land, and drafts the follow-up for you to approve.
With 15 rules it cannot talk its way around
- A paid or written-off invoice is never chased again. Follow-ups are switched off permanently, not deferred.
- A disputed invoice stops automated chasing entirely and goes to a person to resolve.
- A promise to pay on a date pauses reminders until that date has passed. Collectly checks back the day after, not on the day.
- At least three days between reminders on the same invoice, so re-running the analysis cannot turn into nagging. A resent or corrected invoice the customer has just asked for is not a reminder, and still waits for your approval.
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