Miles vs cash for flights comes down to one sum: what each mile is worth on the ticket you want, after the taxes you still pay. Divide the cash fare minus those taxes by the miles needed. If the answer is lower than what each mile cost you to earn, paying cash is the better deal.
This guide shows the calculation with two worked examples. It does not recommend any card or programme; it gives you the method.
The Miles vs Cash Formula for Flights
Value per mile (cents) = (cash fare − taxes and charges on the award) ÷ miles needed × 100
Three points about the inputs:
- Use the real cash fare for the same flight, date and cabin, not a sale fare on another day.
- Subtract what you still pay in cash. Singapore Airlines states that taxes, charges and fees on KrisFlyer awards are payable in addition to the miles, by credit or debit card. They include airport charges and, for tickets sold from 1 October 2026 on flights from 1 January 2027, Singapore’s SAF levy.
- Count the miles at the award level you can actually book. Saver and higher award levels need different amounts.
Worked Example 1: A S$600 Short-Haul Fare
Illustration only, with our own figures.
- Cash fare: $600 return in economy
- Taxes and charges you still pay on an award: $120
- Miles needed: 30,000
Value per mile = ($600 − $120) ÷ 30,000 × 100 = 1.6 cents
Worked Example 2: A $3,000 Long-Haul Business Fare
- Cash fare: $3,000 one way in business
- Taxes and charges on the award: $200
- Miles needed: 90,000
Value per mile = ($3,000 − $200) ÷ 90,000 × 100 = 3.1 cents
| Short-haul economy | Long-haul business | |
|---|---|---|
| Cash fare | $600 | $3,000 |
| Cash still paid on award | $120 | $200 |
| Miles needed | 30,000 | 90,000 |
| Value per mile | 1.6 cents | 3.1 cents |
The short version: Miles tend to be worth more on expensive tickets, because the taxes you still pay are a smaller share of the fare. On cheap flights, paying cash and keeping the miles is often the better choice.
What Did Each Mile Cost You?
The other half of the comparison is the cost of earning the miles. If you put spending on a miles card instead of a cashback card, each mile cost you the cashback you gave up.
An illustration: a cashback card returning 1.5% versus a miles card earning 1.2 miles per dollar on the same spend. Each dollar earns either 1.5 cents or 1.2 miles. So each mile cost 1.5 ÷ 1.2 = 1.25 cents of cashback given up.
On those assumptions, the $600 redemption (1.6 cents) beats the cashback, and the $3,000 one (3.1 cents) beats it by more. A redemption worth 1 cent a mile would have been worse than taking the cash.
Our cashback vs miles calculator does this sum with your own spending, and the guide to cashback vs miles cards explains the trade-off in more detail.
Costs People Forget
- Conversion fees. Some cards charge a fee to convert points into airline miles. Include it in the cost per mile.
- Annual fees on miles cards, unless waived.
- Interest. MoneySense warns that credit card interest is charged on unpaid balances. Rewards never outweigh interest, so only chase miles if you pay in full.
- Expiry and availability. Miles programmes have expiry rules and limited award seats. Read the programme terms before saving for a specific trip.
- Departure charges are rising. CAAS has announced that the Passenger Service and Security Fee rises from $46.40 to $49.40, and the Aviation Levy from $8 to $10, on 1 April 2027. Award tickets pay these too.
When Cash Is the Better Deal
- The fare is low and the taxes on the award are a large share of it.
- A sale fare is available that award pricing does not reflect.
- You would have to buy or transfer miles at a cost to reach the award level.
- You value flexibility; award changes and cancellations have their own fees and rules.
What To Do Next
- Run the formula on your next trip with real numbers from the airline’s site for both cash and award prices.
- Check what your card earns and costs in our air miles credit cards comparison.
- See how departure charges add up in our explainer on the SAF levy on air tickets.
- Budget the whole trip, not just the flight, with the family holiday budget guide.
