AR aging calculator — buckets, days overdue and reserve
Paste your open invoices with days overdue to get AR aging buckets, percentage mix, weighted average days overdue and a suggested bad debt reserve.
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Short answer
An AR aging calculator sorts open invoices into current, 1–30, 31–60, 61–90 and 90+ day buckets by how far past due each one is. On a $444,700 ledger, $319,200 (71.8%) is past due at a weighted average of 37.2 days overdue, giving a suggested reserve of $25,069.
An AR aging report answers two questions: how much of what you are owed is late, and how late. The buckets matter because collectability falls off a cliff with age — an invoice 100 days past due behaves nothing like one 10 days past due, even from the same customer.
Paste one invoice per line as an amount followed by days overdue. This AR aging calculator sorts them into current, 1–30, 31–60, 61–90 and 90+ buckets, shows the value mix, weights days overdue by dollars, and applies your own loss rates to suggest a reserve.
Your numbers
One invoice per line: amount, then days overdue. Commas, tabs or spaces all work. Customer names are ignored, 0 or negative days counts as current, and negative amounts (credit memos) reduce their bucket.
Result
Total open AR analysed
$444,700
$319,200 (71.8%) past due · weighted average 37.2 days overdue
Current (not yet due)$125,500 · 28.2%
1–30 days$171,950 · 38.7%
31–60 days$94,400 · 21.2%
61–90 days$43,250 · 9.7%
90+ days$9,600 · 2.2%
Invoices parsed10
Past due$319,200 · 71.8%
Weighted average days overdue37.2 days
Weighted across the whole ledger26.7 days
Beyond 60 days$52,850 · 11.9%
Suggested reserve$25,069 · 5.6% of AR
10 lines parsed · total AR = $444,700
past due = $444,700 − $125,500 current = $319,200
Σ(amount × days overdue) = 11,858,650 ÷ $319,200 = 37.2 days
reserve = Σ(bucket × loss rate) = $25,069 = 5.6% of AR
Aged from the due date. Credit memos entered as negative amounts net against their bucket.
Bucket
Amount
Invoices
% of AR
Loss rate
Reserve
Current (not yet due)
$125,500
2
28.2%
0.5%
$628
1–30 days
$171,950
3
38.7%
2.0%
$3,439
31–60 days
$94,400
2
21.2%
8.0%
$7,552
61–90 days
$43,250
2
9.7%
20.0%
$8,650
90+ days
$9,600
1
2.2%
50.0%
$4,800
Total
$444,700
10
100.0%
5.6%
$25,069
11.9% of value sits beyond 60 days at a weighted 37.2 days overdue. Call the largest accounts in the 61–90 bucket before they roll into 90+, where recovery drops sharply.
Everything is computed in your browser. Nothing you type is sent anywhere or stored.
The formula
Weighted average days overdue = Σ(invoice amount × days overdue) ÷ Σ(invoice amount)
invoice amount
Open balance on the invoice, net of part payments and credit notes. Negatives are allowed and reduce the bucket.
days overdue
Today minus the due date. Zero or negative means the invoice is current and not yet due.
bucket loss rate
The share of each bucket you historically fail to collect. Used for the reserve, one rate per bucket.
Weighting by value is the whole point. A simple average of days overdue treats a $600 invoice and a $128,400 invoice as equals, which is how teams end up chasing the wrong accounts. The reserve is a separate calculation: Σ(bucket amount × bucket loss rate).
Worked example
Invoices pasted
10 lines
Total open AR
$444,700
Current (not yet due)
$125,500
Loss rates
0.5 / 2 / 8 / 20 / 50%
Result
$319,200 past due · 37.2 days weighted · $25,069 reserve
Ten lines total $444,700, of which $125,500 is not yet due, leaving $319,200 (71.8%) past due. Σ(amount × days overdue) is 11,858,650, and dividing by $319,200 gives a weighted average of 37.2 days overdue. Applying 0.5/2/8/20/50% loss rates by bucket produces a reserve of $25,069, or 5.6% of the ledger.
Why 30-day AR aging buckets, and when to change them
Thirty-day buckets exist because monthly statement cycles do. They are a reporting convention, not a law. If your standard terms are net 15, 30-day buckets hide a full extra cycle of lateness inside the first bucket, and a 15/30/45/60 split tells you far more.
Bucket
What it usually means
Action that actually works
Current
Not yet due. Nothing to collect.
Confirm the invoice was delivered and is not sitting in a portal unapproved.
1–30 days
Administrative slippage: approvals, payment runs, missing PO numbers.
A dated reminder with the invoice attached. Most of this bucket self-clears.
31–60 days
Something is wrong that a reminder will not fix.
Phone the AP contact and confirm there is no dispute or short-shipment behind it.
61–90 days
Collection risk is real. Escalate.
Credit hold on new orders, escalate to the customer's finance lead, agree a written plan.
90+ days
Assume you will not collect all of it.
Legal, factoring or write-off decision. Reserve heavily and stop shipping on terms.
Work the report by value, not by date
Most ledgers are far more concentrated than the row count implies: a handful of invoices carry the majority of the past-due value. Sort the 61–90 and 90+ buckets by amount and call the top five accounts. Chasing the oldest small invoices feels productive and moves almost no cash.
Age from the due date, not the invoice date. Aging from the invoice date makes every net-30 customer look 30 days late.
Apply unapplied cash and credit notes first. Unapplied receipts routinely make a 90+ bucket look worse than it is.
Split disputes out of the aging. A disputed invoice is a product or service problem sitting in a finance report; collections cannot close it.
Check billing lag before blaming collections. If invoices go out four days after shipment, four days of your DSO was never a collections issue.
Watch the mix, not the total. A stable total AR with value migrating from 1–30 into 31–60 is a deteriorating ledger even though the headline has not moved.
Setting loss rates for the reserve
The bucket rates seeded above are conventional starting points, not benchmarks. Replace them with your own history: for each bucket, take invoices that entered it over the last two or three years and work out what share was eventually written off. That number is defensible in an audit; a rate copied from a template is not.
Getting a clean aging without the export
Every ERP has an aging report and every finance team still exports it, because the on-screen version cannot easily net credit memos, exclude disputes, or show the same ledger by sales rep and by subsidiary at once.
With ERPray you ask for "open AR by aging bucket, netting credit memos, excluding disputed invoices, by subsidiary" and get it computed live from your own account, with the query shown underneath so you can check exactly which invoices were counted.
Frequently asked questions
What are the standard AR aging buckets?
Current, 1–30, 31–60, 61–90 and 90+ days past due. The buckets follow monthly statement cycles rather than any accounting rule, so shorter buckets are worth using when your terms are shorter than net 30. Always age from the due date, not the invoice date.
How do you calculate weighted average days overdue?
Multiply each invoice's open amount by its days overdue, add those products up, then divide by the total amount. On a $319,200 past-due ledger where the products total 11,858,650, the weighted average is 37.2 days. Weighting by value stops a pile of small invoices distorting the picture.
What is a good AR aging profile?
One where over 85% of the value is current or within 30 days, and the over-60 buckets stay under about 5% of total AR. The absolute shape depends on your terms and customer mix, so watch the direction of travel between the buckets rather than a single month's percentages.
How do you calculate a bad debt reserve from an aging report?
Apply a loss rate to each bucket and add the results. With 0.5%, 2%, 8%, 20% and 50% against buckets of $125,500, $171,950, $94,400, $43,250 and $9,600, the reserve is $25,069 — about 5.6% of AR. Derive your own rates from historical write-offs by bucket.
Why does my AR aging report not match the GL?
Usually unapplied cash, credit memos posted without being applied to an invoice, foreign-exchange revaluation, or a cut-off difference between the report date and the posting period. Reconcile the aging total to the AR control account every close, and investigate before the difference becomes a habit.
Should credit memos appear in the aging?
Yes, aged from their own date, and netted against the customer's balance. Leaving them out overstates what you are owed and sends collectors after invoices the customer has already been credited for. Enter them here as negative amounts on their own line.
This calculator needs you to find the inputs first. ERPray pulls them from your own ERP account and computes the answer live — with the exact query shown so you can check it.