Free interactive tool
Mile Sale Break-Even Calculator
The mile-sale break-even calculator computes the effective cost per mile of a buy-miles promotion: the sale price per mile, grossed up by any purchase tax or processing fee, divided by the bonus multiplier. Buying miles only makes sense when that effective cost is clearly below the cents per point you will get from a specific redemption you have already found and can book right now — the calculator compares the two and says buy, top-off only, or skip.
The formula
effective cost per mile (¢) = price per mile × (1 + purchase tax rate)
÷ (1 + bonus rate)
buy only if: effective cost per mile < cpp of a CONFIRMED redemptionTwo inputs come from the sale page (price and bonus); the redemption value comes from your own work. No confirmed award to compare against? Stop — speculative mile buying is paying cash today for a currency the program can reprice at any time.
Run your numbers
Before any bonus — the number you pay for.
From the sale page, in cents, before purchase taxes.
A “100% bonus” doubles the miles: enter 100.
Whatever the checkout adds on top; 7.5 here is an example placeholder, not a rate quote.
From an award you've actually found — compute it with the points-vs-cash calculator.
- Total miles received (with bonus)
- 100,000 mi
- Total purchase price (with tax)
- $1,585.63
- Effective cost per mile
- 1.59¢
- Break-even redemption value
- 1.59¢
The pre-filled numbers are a hypothetical example, not a live sale price, bonus rate, or tax rate. The airline’s buy-miles checkout is the only source of truth for today’s terms.
Worked example (hypothetical numbers)
A sale offers miles at 2.95¢ each with a 100% bonus, plus a 7.5% purchase fee (hypothetical numbers, not a live sale). Effective cost = 2.95 × 1.075 ÷ 2.0 = 1.59¢ per mile. Against a confirmed award you would redeem at 1.6¢, that is break-even at best — skip; against a confirmed 2.2¢ business-class redemption, the purchase clears the bar.