Buy vs Subscribe: the Break-even Math (with Opportunity Cost Baked In)
The classical buy-vs-subscribe comparison: divide upfront cost by monthly fee, get the break-even month. $500 upfront vs $15/month = 33 months. Use it longer than that, buy wins.
That math is incomplete. Three corrections shift the answer.
The full break-even formula
We ran $500 upfront vs $15/month through the calculator, both with and without the corrections:
| Method | Break-even month |
|---|---|
| Naive (price ÷ monthly fee) | 33 |
| + Opportunity cost on $500 (7% real return) | 28 |
| + 8% annual subscription price growth | 24 |
| + 30% resale value at year 5 | 19 |
| Full math (all three corrections) | 19 |
The honest break-even at 19 months is a different decision than 33. If you’ll use the thing for 18 months: subscribe. For 24 months: buy. The naive 33-month calculation would have told you “buy” in either case — wrong half the time.
Why each correction matters
Opportunity cost on the upfront. Money spent on a purchase is no longer earning a market return. $500 not invested for 5 years at 7% real misses ~$200 of growth. Practically, the buy path has an “invisible” cost equal to that forgone return.
Annual subscription price growth. Almost all subscriptions raise prices. Streaming services typically run 5-12% annually. Software-as-a-service is similar. The “$15/month” you sign up for becomes $22/month in 5 years. Lifetime cost compounds against the subscription path.
Resale value at end-of-life. A 5-year-old laptop has resale value of 20-40% of original price. A 10-year-old appliance has near-zero. Including the recovered value at sale time pulls the buy-path break-even forward.
The three corrections move the answer in different directions. Opportunity cost favors subscribing. Subscription price growth favors buying. Resale value favors buying. Net effect: usually shifts the break-even forward by 30-50% from the naive answer.
When each path clearly wins
Beyond the math, four heuristics that work without running the calculator:
Buy if:
- You’ll use it daily for 5+ years
- Resale market is healthy (good for cars, instruments, well-known brands)
- Subscription price growth is high in your category (streaming bundles, gym chains)
- You value not having a recurring bill (psychological lever — real for some people)
Subscribe if:
- Technology obsoletes fast (phones, laptops, cameras under 3 years)
- Your usage is uncertain or temporary (3-month project, 6-month travel)
- The subscription includes ongoing value that’s hard to replicate (cloud sync, software updates, content library)
- You want optionality to stop without a sunk cost
Where the math doesn’t apply
- Items you’d own anyway. A car you’d buy regardless of subscription alternatives doesn’t have a subscription path; it’s just a car. The framework only applies when the choice is real.
- Heavily-bundled subscriptions. Apple One, Amazon Prime, Microsoft 365 bundle dozens of services. The “buy alternative” doesn’t really exist. Different evaluation framework.
- Lifestyle subscriptions. Gym memberships, meal kits — these aren’t really comparable to “buying the equivalent” because the convenience or accountability is the product, not the underlying goods.
- Cars and homes. Different math entirely (rent vs buy, lease vs purchase). Use the relevant calculators.
What to actually do
- Pick the specific item or service.
- Find true upfront cost (price + delivery + setup) and true monthly fee (incl. taxes, hidden upsells).
- Run the calculator with realistic assumptions on price growth (5-10% for most subscriptions), expected use period (be honest), and resale value (0% for most software, 20-40% for hardware).
- The break-even month is your threshold. Use the thing longer → buy; shorter → subscribe.
Open the Buy vs Subscribe Calculator → and run your specific decision. The default 7% return / 5% subscription growth captures most situations; override based on your context.
Quick answers
What's the simple rule for buy vs subscribe?
Compute total cost over your honest expected use period for each path. Include opportunity cost on the upfront purchase amount (it could have been invested), annual price growth on the subscription (most services raise prices), and resale value at end-of-life on the buy side. The break-even month tells you which path wins.
Why does opportunity cost matter for one-time purchases?
$500 spent today vs $500 invested for 5 years at 7% real return: $500 vs $701. Buying isn't just $500; it's $500 plus the $201 of forgone growth. For long horizons or large purchases this gap dominates the comparison.
How does annual price growth on subscriptions change the math?
A $15/month subscription that rises 8%/year becomes $22 in year 5 and $32 in year 10. Total spending over 10 years is $2,400 (no growth) vs $2,610 (with 8% growth). For long horizons the difference is meaningful; for short horizons it's negligible.