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Lessons · Accounting · inventory: FIFO and LIFO

FIFO and LIFO: which cost leaves first

When identical units were bought at different prices, the books need a rule for which cost goes out with each sale. FIFO takes the oldest cost first; LIFO takes the newest. The rule changes cost of goods sold and what is left in inventory, not what is on the shelf.

Hone is a place to practise a career, one idea a day. This is one of its lessons, written out in full and free to read without an account.

What it is for

Prices rose during the year and the owner asks why profit fell when sales did not. Under LIFO the newest, dearest cost went out with every sale. Same shop, same sales, same stock: a different rule and a different profit.

How to think about it

List the purchases in order with quantity and unit cost. For FIFO, take the units sold from the top of the list; for LIFO, from the bottom. Add up what you took. What you did not take is ending inventory, and the two must add back to the total cost.

Worked example

Bought 10 at 5 = 50, then 10 at 7 = 70; total 120 for 20 units; sold 12
Two layers of cost, one sale.
FIFO cost of goods sold = 10 × 5 + 2 × 7 = 50 + 14 = 64
The oldest ten at 5 go first, then two from the newer layer.
LIFO cost of goods sold = 10 × 7 + 2 × 5 = 70 + 10 = 80
The newest ten at 7 go first, then two from the older layer.
Ending inventory: FIFO 120 − 64 = 56 (8 × 7); LIFO 120 − 80 = 40 (8 × 5)
What was not sold. Either way, sold plus left equals what was bought.

Your turn

Ten at 6, then ten at 9, thirteen sold. Write the FIFO line with the second cost filled in.

FIFO cost of goods sold = 10 × 6 + 3 ×  = 87

The trap

Thinking FIFO describes which physical box left the warehouse. It describes which cost left the books. The warehouse can hand out any box it likes.

Practise inventory: FIFO and LIFO on HoneA question on it now, a coding challenge where there is one, and it is remembered for review. Free, no email needed.