Inventory Cost Basis Calculator for Resellers
Allocate purchase price, freight, tax, repairs, and supplies across a resale lot by units, weight, or custom share, then export per-item COGS.
What this tool helps you do
Allocate purchase price, inbound shipping, tax, repairs, and supplies across mixed resale inventory, then export a traceable per-item cost basis.
Interactive inputs and calculations load after the app boots. Use this prerendered preview to understand what the tool covers before opening the live experience.
Best for
- inventory cost calculator
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Allocate a resale lot into traceable per-item COGS
Use this inventory cost calculator when one receipt or auction invoice covers several items and each SKU still needs a usable cost basis. Add purchase price, inbound freight, purchase tax, shared repairs, and shared supplies, then allocate the landed lot cost by units, weight, or a documented custom share.
The calculator keeps the equation and allocation weights visible, reconciles the allocated total to the landed lot cost, and exports a CSV with quantity, allocation percentage, allocated cost, and unit cost. It is designed for thrift hauls, shipped auction lots, mixed pallets, storage-unit recoveries, and other multi-item buys.
IRS Publication 334 says merchandise purchase cost and freight-in are part of cost of goods sold and inventory practices must be consistent. Publication 538 describes specific identification when actual costs can be matched to individual items. This operational worksheet does not choose a tax method for you.
- Inputs: purchase price, inbound shipping, purchase tax, lot repairs, lot supplies, item name, quantity, weight, and optional custom share.
- Allocation methods: equal per unit, total row weight, or normalized custom share.
- Outputs: landed lot cost, allocated total, per-row allocation, per-unit cost, warnings, and copy/download CSV.
- Boundary: cost allocation and COGS documentation, not storage rent, SKU naming, marketplace fees, or tax filing advice.
Original lot-allocation scenarios
| Scenario | Shared costs | Useful allocation |
|---|---|---|
| Mixed thrift haul | One receipt plus tax, cleaning, and supplies. | Custom share when one jacket or pair of shoes drove most of the lot value. |
| Shipped auction lot | Hammer price, inbound freight, tax, repair, and packing supplies. | Weight when freight burden is the main reason shared cost differs. |
| Small liquidation pallet | Pallet price, freight, testing, repair, and handling supplies. | Equal units only when the sellable units are comparable; otherwise document custom shares. |
IRS inventory sources checked August 17, 2026
IRS Publication 334
Official small-business guidance on inventory, cost of goods sold, purchase cost, freight-in, and consistent inventory practices.
IRS Publication 538
Official accounting-method guidance including specific identification for inventory costs.
IRS Publication 583
Official recordkeeping guidance identifying purchase and sales records used to support inventory costs.
Frequently Asked Questions
How do I calculate cost basis for items bought in one resale lot?
Add the lot purchase price and shared acquisition costs, choose an allocation weight for each item or group, then divide each row’s allocated cost by its quantity. Save the receipt, freight and repair evidence, allocation method, and exported result so each SKU remains traceable.
Should I allocate a mixed lot equally by item?
Only when the units are genuinely similar. Equal-per-unit allocation can distort a lot when one valuable item drove the purchase and several low-value pieces came with it. Use weight when freight burden is the main difference, or a documented custom share when evidence supports unequal allocation.
Does inbound shipping belong in inventory cost?
IRS Publication 334 says freight-in, express-in, and cartage-in on merchandise purchased for sale are part of cost of goods sold. Tax treatment depends on your accounting method and facts, so use the calculator as a documentation aid and confirm your method with a qualified tax professional.
Can I paste spreadsheet rows into the inventory cost calculator?
Yes. Paste CSV rows with item name, quantity, total row weight, and custom share. The tool imports the rows, performs the allocation, and can copy or download the completed allocation as CSV.
Is this inventory cost calculator tax advice?
No. It creates a repeatable operational allocation and audit trail. It does not select an accounting method, determine whether a specific repair or supply must be capitalized, or prepare a tax return.
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