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Supplier Purchases & Payment Days Calculator

Estimate payable days using average payables and calculated purchases.

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Calculator inputs

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How to use this calculator

  1. Enter the known values in the units shown. Results update as you type.
  2. Edit a calculated value to solve backwards, or lock a value to hold it fixed.
  3. Use the worked example to check the method. Reset restores the starting fields.

Use the result with context

Results are estimates for planning and education. Confirm rates, taxes, fees, and legal requirements with the relevant institution or a qualified professional before making a financial decision.

Formula and method

Payables of 8,000 and 12,000 average 10,000. Inventory rising from 20,000 to 25,000 with cost of goods sold of 95,000 implies purchases of 100,000. Over 360 days, payable days are 36.

Purchases = closing inventory − opening inventory + COGS; payable days = average payables ÷ purchases × period days

Worked example

Enter these known values and leave the other values blank.

Beginning account payable
8000 USD
Ending accounts payable
12000 USD
Beginning inventory
20000 USD
Ending inventory
25000 USD
Cost of goods sold
95000 USD
Days in accounting period
360 days
Average accounts payables
10000 USD
Purchases
100000 USD
Days payable outstanding
36 days

Assumptions and limitations

  • This version divides by purchases, not cost of goods sold. It assumes the inventory movement reconciles to purchases and uses matching trade payables. Write-downs, production adjustments and cash purchases can require a refined denominator.
  • Use consistent periods, currency and accounting definitions. The result follows the stated formula and the figures you supply.

Common questions

Why might another payable-days figure differ?

This version divides by purchases, not cost of goods sold. It assumes the inventory movement reconciles to purchases and uses matching trade payables. Write-downs, production adjustments and cash purchases can require a refined denominator.

References

The calculation equations, inverse formulas, units, and input rules were imported from this source. Bookify provides the interface and equation solver.

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