What is the price per use of this purchase?

People type this into search every day: cost per use calculator.

The useful version is small. Add the price and the upkeep you expect to pay. Divide by the number of times you expect to use the thing. Compare that with the other option, done the same way.

This page walks the price per use calculator on labeled inputs. It is not a verdict on which boots, pans, or tools you should buy.

Price plus upkeep, then divide

The calculator stores two options.

Option A is a price divided by uses. Option A has no upkeep field. If A needs sharpening, filters, or a service, add that cash to A’s price before you type it.

Option B is (price + upkeep) ÷ uses.

The lower result wins. A tie goes to A, because the comparison keeps A when the two unrounded costs are equal.

The third line is always the gap times 100. It is labeled “difference per 100 uses.” It is not a second bill, and it stays on that scale even when you typed one use.

Resale, the time value of money, and a change in how often you actually use it are outside the formula. The assumptions say expected uses should match behavior. If they do not, the winner is a story about the numbers you typed.

Shelf unit price is a different division. NIST describes unit pricing as cost per unit of measure, such as per gram or per count. The unit price post works that problem. Price per use asks how many times the object gets used, which a shelf label does not know.

Example 1: the published defaults

Here are the calculator defaults:

• option A price: $90
• expected uses A: 80
• option B price: $180
• expected uses B: 300
• option B upkeep: $25

A: 90 ÷ 80 = 1.125, which prints as $1.13 per use.

B: (180 + 25) ÷ 300 = 205 ÷ 300 = 0.68333, which prints as $0.68 per use.

Gap: (1.125 − 0.68333) × 100 = 44.166, which prints as $44.17 per 100 uses.

Winner: Option B.

The sticker on B is twice A’s sticker. B still wins because 300 uses is 3.75 times 80 uses, and the $25 upkeep is small next to $180.

180 ÷ 300 = $0.60 of price per use. 25 ÷ 300 = $0.0833, which is the rest of the $0.68. Drop the upkeep and B would print $0.60. The winner would not change. The gap per 100 uses would, from $44.17 to (1.125 − 0.60) × 100 = $52.50.

Example 2: what if B is only used 120 times

Hold $90, 80 uses, $180, and $25. Change B’s uses from 300 to 120.

B: 205 ÷ 120 = 1.70833, which prints as $1.71 per use.

A is still $1.13.

Gap: (1.70833 − 1.125) × 100 = $58.33 per 100 uses.

Winner: Option A.

Same objects, fewer uses on the expensive one, and the label flips. The break-even use count for B, against A’s $1.125, is 205 ÷ 1.125 = 182.22 uses.

At 182 uses, 205 ÷ 182 = 1.12637. Both lines print $1.13. The unrounded B is still higher, so the label stays Option A, and the gap prints $0.14 per 100 uses.

At 183 uses, 205 ÷ 183 = 1.12022, which prints as $1.12. The label flips to Option B. The gap prints $0.48 per 100 uses.

If you will not reach about 183 uses of B, the $180 option is the expensive one on these defaults.

Example 3: a cheaper pair and a longer-lived pair

A common clothing version of the same formula:

• A: $60 and 40 uses
• B: $180, no upkeep, 200 uses

A: 60 ÷ 40 = $1.50 per use.

B: 180 ÷ 200 = $0.90 per use.

Gap: $60.00 per 100 uses.

Winner: Option B.

Forty wears is a short season. Two hundred wears is several seasons. The $120 sticker gap is real. Spread over the uses above, B is $0.60 cheaper each wear.

Change the uses and the story changes. At 80 uses of B and the same $180, B would be 180 ÷ 80 = $2.25, and A would win. I am not going to invent how many times a pair of shoes actually gets worn. Type the number you believe.

Example 4: upkeep that swamps the sticker

• A: $40 and 50 uses
• B: $120 plus $80 upkeep, and 100 uses

A: 40 ÷ 50 = $0.80 per use.

B: (120 + 80) ÷ 100 = $2.00 per use.

Gap: $120.00 per 100 uses.

Winner: Option A.

B’s sticker is three times A’s. The upkeep is another $80, and B only lasts twice as many uses. 100 × $2.00 = $200, which is the whole $120 + $80 pile. 50 × $0.80 = $40, which is A’s whole price. Over 100 uses of A you would buy two of them, still $80, against B’s $200.

Example 5: same use count, different stickers

• A: $25 and 100 uses
• B: $80, no upkeep, 100 uses

A: 25 ÷ 100 = $0.25.

B: 80 ÷ 100 = $0.80.

Gap: $55.00 per 100 uses.

Winner: Option A.

When the use counts match and upkeep is zero, price per use is just a scaled sticker. The cheaper object wins. The formula starts to matter when the use counts differ, or when upkeep is not zero. Example 4 was that second case. Example 2 was the first.

Example 6: a long life shrinks a high sticker

• A: $30 and 200 uses
• B: $150 plus $20 upkeep, and 2,000 uses

A: 30 ÷ 200 = $0.15 per use.

B: 170 ÷ 2,000 = 0.085, which prints as $0.09 per use.

Gap: (0.15 − 0.085) × 100 = $6.50 per 100 uses.

Winner: Option B.

Two thousand uses is a strong assumption. If B stops at 400 uses, 170 ÷ 400 = $0.43, and A wins at $0.15. The $6.50 gap is what you get only if the 2,000 uses happen.

Example 7: the sticker-price mistake

People compare $40 with $120 and stop.

• A: $40 and 20 uses
• B: $120 plus $10 upkeep, and 400 uses

A: 40 ÷ 20 = $2.00 per use.

B: 130 ÷ 400 = 0.325, which prints as $0.33 per use.

Gap: (2.00 − 0.325) × 100 = $167.50 per 100 uses.

Winner: Option B.

A is the cheap sticker and the expensive use. Twenty uses means the $40 is gone quickly. Four hundred uses means the $130 pile is a third of a dollar each time.

Example 8: what if I use A more often

Hold B at the defaults: $180 + $25 over 300 uses, $0.68 per use. Change only A’s uses. A’s price stays $90.

• 20 uses: 90 ÷ 20 = $4.50. Gap $381.67 per 100 uses. Winner B.
• 40 uses: 90 ÷ 40 = $2.25. Gap $156.67. Winner B.
• 80 uses (the default): $1.13. Gap $44.17. Winner B.
• 131 uses: 90 ÷ 131 = 0.68702, which prints as $0.69. Gap $0.37. Winner B.
• 132 uses: 90 ÷ 132 = 0.68182, which prints as $0.68. Gap $0.15. Winner A.
• 160 uses: 90 ÷ 160 = 0.5625, which prints as $0.56. Gap $12.08. Winner A.

The unrounded cross is 90 ÷ (205 ÷ 300) = 131.71 uses. 132 is the first whole number where the tool names A. At 132 the screen shows $0.68 on both lines. The winner still follows the unrounded values, which is why the gap can print $0.15 while the two prices look identical.

Example 9: one use, and a gap that looks huge

• A: $15 and 1 use
• B: $200 and 1 use, no upkeep

A: $15.00 per use.

B: $200.00 per use.

Gap: (200 − 15) × 100 = $18,500.00 per 100 uses.

Winner: Option A.

Read the third line as a scale, not as a checkout total. You typed one use. The tool still multiplies the $185 gap by 100, because that line is defined as the difference per 100 uses. The money you would actually spend on this single use is $15 or $200.

If you later use B a hundred times and A once, you are in a different example. Change the use fields. Do not treat $18,500 as the cost of choosing B once.

A subscription is a different split

Price per use has no monthly fee. The subscription vs one-time purchase calculator compares a monthly charge with buying once.

Its defaults:

• subscription: $18 a month
• one-time purchase: $340
• annual upkeep of owning: $30
• years: 3

Subscribe: 18 × 12 × 3 = $648.00.

Own: 340 + 30 × 3 = $430.00.

Winner over these three years: Buy once.

Break-even month: 340 ÷ (18 − 30 ÷ 12) = 340 ÷ 15.5 = 21.9 months.

The subscriptions post adds up the monthly charges you already pay. A cup of coffee has the same shape as price per use, one purchase spread over servings, in the homemade coffee post.

The nine price-per-use runs

Open the price per use calculator and replace the use counts with the ones you will actually hit. The label follows those counts.