How the calculation works
Each row is one device category. With N devices costing C each to replace today on a Y-year cycle:
- Fleet value = N × C: replacing every device at today’s price.
- Smoothed budget = N × C ÷ Y a year: replacing 1/Y of the fleet every year.
- Big-bang refresh = N × C in a single year, then nothing until the next cycle.
- Past cycle = N × the percentage past cycle, rounded to whole devices; the backlog is those devices × C.
- Catch-up year = backlog + (fleet value − backlog) ÷ Y: clear the backlog and replace the usual share of the rest, assuming the rest are spread evenly in age.
Totals add every row; the big-bang line also shows how many smoothed years it equals.
Buy vs DaaS, for rows with a DaaS price D per device a month and a term of T months:
- Buy, per device a month = C ÷ (Y × 12), and over the term N × C × T ÷ (Y × 12).
- DaaS over the term = N × D × T.
- The difference is DaaS minus buy. A DaaS price equal to C ÷ (Y × 12) breaks even on this basis.
Assumptions: costs are today’s prices, with no inflation, financing, resale value or time value of money. The buy figure is the hardware alone: support, imaging, deployment and disposal costs that a DaaS price may include are not added. The calculator doesn’t use any market prices; every figure comes from you.
Worked example
A company with a small server room plans its refresh budget, with a 36-month DaaS quote for laptops:
| Row | Devices | Unit cost | Cycle | Past cycle | DaaS price |
|---|---|---|---|---|---|
| Laptops | 120 | $1,400 | 4 years | 25% | $45 a month |
| Desktops | 40 | $1,100 | 5 years | 10% | none |
| Servers | 6 | $12,000 | 5 years | 0% | none |
| Network gear | 20 | $2,500 | 7 years | 50% | none |
- Smoothed budget: $168,000 ÷ 4 + $44,000 ÷ 5 + $72,000 ÷ 5 + $50,000 ÷ 7 = $42,000 + $8,800 + $14,400 + $7,142.86 = $72,342.86 a year ($6,028.57 a month).
- Big-bang refresh: the whole $334,000 fleet in one year, 4.6 times the smoothed year.
- Backlog: 30 laptops, 4 desktops and 10 network devices are past their cycle: 44 devices, $71,400.
- Catch-up year: laptops $42,000 + $126,000 ÷ 4 = $73,500; desktops $4,400 + $39,600 ÷ 5 = $12,320; servers $14,400; network $25,000 + $25,000 ÷ 7 = $28,571.43. Total $128,791.43.
- Laptops, buy vs DaaS over 36 months: buying works out to $1,400 ÷ 48 = $29.17 a laptop a month, $126,000 for 120 laptops over the term. DaaS at $45 is $194,400, $68,400 more than the hardware alone. That gap is what the DaaS services would need to be worth to break even.
Choosing between smoothing and a big-bang refresh
A smoothed budget is easier to fund and keeps the fleet’s age spread out, so no single year carries every replacement. A big-bang refresh can simplify standardization and deployment, but it creates a peak year and ages every device together, so the next refresh is a peak too. Many teams land in between, refreshing one category or department a year.
Before comparing a device-as-a-service quote, list what it includes and price what buying would need on top: lifecycle work such as imaging and support, and disposal. How the two options land on the books is a CapEx vs. OpEx question for your finance team. To add financing, depreciation, tax and present value to a single buy vs lease or subscription decision, use the lease vs buy calculator.
