Open-to-Buy Calculator

Quick guide

How to use this calculator

Gather Planned ending inventory, Planned sales, Planned reductions, Opening inventory, and Inventory already on order for the same business scenario before calculating.
Keep units and time bases aligned: daily demand needs lead time in days, and item costs must match the quantity represented by one inventory unit.
Apply the displayed open-to-buy result to the stated decision only after checking every entered assumption.

Calculation method

Open to buy = planned ending inventory + planned sales + planned reductions − opening inventory − on-order inventory.

The calculation uses these named inputs: Planned ending inventory, Planned sales, Planned reductions, Opening inventory, and Inventory already on order. No market rate, benchmark, tax rule, or accounting classification is inserted automatically.

Fixed-decimal arithmetic remains exact through display unless a result is explicitly labelled approximate, such as a square-root inventory quantity.

Inventory planning and replenishment

Where the Open-to-Buy Calculator helps

Estimate retail purchasing capacity for an entered planning period.

Use the result to translate entered demand, lead time, order cost, holding cost, and service assumptions into a planning quantity or interval.

Prepare a purchase-order scenario
Stress-test a supplier lead-time change
Compare ordering and holding-cost assumptions

Interpretation check

How to audit the result

Recalculate the scenario when any of these inputs changes: Planned ending inventory, Planned sales, Planned reductions, Opening inventory, and Inventory already on order.

Keep this formula beside the result: Open to buy = planned ending inventory + planned sales + planned reductions − opening inventory − on-order inventory. Then compare the output with the source records and the calculator-specific assumption below.

Confirm that all amounts use one currency and reporting period.
Check that rates, counts, and quantities describe the same population or transaction set.
Save the entered assumptions with the decision; the result alone is not reproducible evidence.

Worked example

Ending target 80,000, sales 150,000, reductions 10,000, opening 70,000, and on-order 20,000 give OTB of 150,000.00.

Open to buy = planned ending inventory + planned sales + planned reductions − opening inventory − on-order inventory.

Supported inputs

Precision and limits

Visible input limits

Fixed decimals accept up to 30 digits and 12 decimal places and are capped at an absolute value of 1e12 per input. Rates are capped at 1000%; percentage shares and method-specific domains may be narrower.

International scope

No currency, tax jurisdiction, accounting framework, payroll rule, marketplace fee schedule, financing term, or industry benchmark is selected automatically.

Decision boundary

Use the result to translate entered demand, lead time, order cost, holding cost, and service assumptions into a planning quantity or interval. Results remain arithmetic scenarios, not accounting records, forecasts, valuations, legal interpretations, professional advice, or recommendations.

Calculator-specific assumptions

This is a scenario from visitor-entered values. Keep currencies, periods, accounting classifications, and operating definitions consistent. It is not accounting, tax, legal, investment, or business advice.