Accounts Receivable Days Calculator
Measure how many days your invoices typically take to turn into cash.
Calculator
Unpaid customer invoices right now (or period-end AR).
Sales on account (not cash sales) for the same window.
Use 30, 90, or 365 to match the sales window.
Results
AR days (DSO)
18 days
Average days to collect
Average daily credit sales
$1,000.00
What this means
AR days around a month or less usually means collections are keeping up with credit sales—still watch a few late outliers.
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Accounts Receivable Days Summary
AR days (DSO) = AR balance ÷ (Credit sales ÷ Days in period). Higher DSO means cash is stuck in unpaid invoices.
Explanation
AR days estimates average collection time.
Average daily credit sales is period credit sales divided by days in the period.
Business implication: growth on slow-paying clients can increase revenue while draining cash.
Step-by-step example
AR $18,000, credit sales $90,000 over 90 days:
- Daily sales: $90,000 ÷ 90 = $1,000
- AR days: $18,000 ÷ $1,000 = 18 days
Formula
Daily credit sales = Credit sales ÷ Days in period
AR days = AR balance ÷ Daily credit sales
Helpful tips
- If DSO rises, tighten terms, require deposits, or chase aging buckets weekly.
- Align DSO with Cash Flow Forecast inflows—don't assume Net 30 when DSO is 50.
FAQ
What are AR days / DSO?
Days sales outstanding estimates how long, on average, it takes to collect credit sales—AR balance divided by average daily credit sales.
Should I use total revenue or credit sales?
Prefer credit sales (invoices on account). Including cash sales understates how slow collectors really are.
What is a good DSO?
Compare to your payment terms. If you offer Net 30 and DSO is 55, collections are lagging. Industry norms vary widely.
How accurate is this calculator?
It uses the classic DSO formula. Timing differences (seasonality, large one-off invoices) can skew a single-period snapshot.
Related tools
Key terms
Accounts receivable days
Definition. How many days, on average, it takes to collect payment after a sale on credit.
In simple terms. Higher AR days mean more of your money sits in unpaid invoices. That affects runway and whether you need deposits or tighter terms.
AR days ≈ (accounts receivable ÷ revenue) × days in period
Example. If AR is $30,000 and monthly revenue is $45,000, AR days are roughly 20 on a 30-day basis (simplified).
Common mistake. Ignoring aging—averages can hide a few very late invoices.
Related calculators. Accounts Receivable Days Calculator, Invoice Due Date Calculator
Related terms. Cash flow, Invoice due date, Late fee
Cash flow
Definition. The movement of cash in and out of the business over a period—not the same as profit on paper.
In simple terms. You can be profitable and still short on cash if customers pay late or you buy inventory up front. Cash-flow views focus on timing.
Net cash flow = cash in − cash out (for the period)
Example. Invoicing $20,000 but collecting $8,000 while paying $12,000 in bills creates a cash squeeze despite strong sales.
Common mistake. Equating booked revenue with cash in the bank.
Related calculators. Cash Flow Forecast Calculator, Accounts Receivable Days Calculator
Related terms. Accounts receivable days, Burn rate, Runway
Invoice due date
Definition. The date payment is expected under your payment terms (Net 15, Net 30, due on receipt, etc.).
In simple terms. Clear due dates set collection expectations. They also feed cash-flow forecasts and late-fee policies.
Due date = invoice date + payment terms (in days)
Example. Invoice dated March 1 on Net 30 is due March 31.
Common mistake. Sending invoices without stated terms, then arguing about “late.”
Related calculators. Invoice Due Date Calculator, Late Fee Calculator
Related terms. Late fee, Accounts receivable days, Cash flow
Notes & Assumptions
Days sales outstanding is a standard working-capital metric in accounting and SMB finance.
Last reviewed: July 2026