iTechGuides is reader-supported. When you buy through links on our site, we may earn an affiliate commission. As an Amazon Associate I earn from qualifying purchases. Learn more
To calculate build-versus-buy total cost of ownership (TCO), compare the full costs of two options that deliver the same capabilities and service levels over the same period. Include one-time work, recurring operations, growth, transition, and exit costs—not just development salaries versus subscription fees. Then test how the result changes when key assumptions change, and assess fit and risk alongside the totals.
1. Define what both options must deliver
Start with the outcome, not the implementation choice. Document the required capabilities, expected workload and growth, integrations, security, reliability, and service levels. Use those requirements as a common baseline for both scenarios.
For the buy case, include the modules, support plans, infrastructure, and third-party components needed to meet the requirements—not merely the vendor’s entry-level price. For the build case, estimate a complete operating solution, including the people and infrastructure required after launch.
Quick wins for a faster PC:
Clear out junk files and repair common Windows errorsFree Scan →Scan for outdated or missing drivers - takes under a minuteDriver Scan →Repair Windows errors before they cause bigger problemsFix Now →2. Choose a shared evaluation period and baseline
Use the same time horizon, usage forecast, and quality-of-service assumptions for both options. Select a period that fits the decision: it should capture implementation and the operating costs that matter, without implying that one horizon is right for every solution. A Microsoft-hosted Frost & Sullivan / Stratecast BI analysis used three years for its particular comparison; that is an example, not a universal rule (2018 BI analysis).
#1 Best Overall
Record the current cost baseline where relevant, then forecast expected growth or contraction. Microsoft recommends establishing a baseline and projecting growth; AWS frames a migration business case around cash flows across a multi-year term (Microsoft financial modeling guidance; AWS business-case guidance).
3. Inventory costs for each scenario
Separate one-time implementation and transition costs from recurring operating costs. Estimate each item by period and make the estimate traceable to labor assumptions, architecture, usage forecasts, and vendor quotes. The categories below are a starting point; include only the line items that apply, but do not omit costs simply because they sit outside the project or subscription budget.
Rank #2
- EASY TO MANAGE - Use this income & expense log book to record your income and expenses each day.Keep your budget in balance, and develop good bookkeeping habits to meet your financial goals
- ACCOUNTING FOR THE WHOLE YEAR - This income and expense tracker is undated and is used to lasts a whole year.The keeping log has 1 page Year Overview, 53 weekly spreads, 2 pages annual summary, 10 notes pages, to track weekly and yearly income & expenses
- HIGH QUALITY - The accounting bookkeeping tracking ledger log book is used to high quality 100gsm pure white paper, teal elastic band and a back pocket for extra space. Make sure you have enough space for all financial activities
- UNIQUE DESIGN & A4 SIZE - Income and expense log book is spiral bound design, size of 8" x 10.5". Just the perfectly size to fit in your backpack, purse or laptop case. Without taking up your space and always helping you keep track of your small business
- THE PERFECT GIFT - Income & expense notebook as gift for woman & man. Use it to track your week-to-week progress, make efficient adjustments whenever needed
| Cost area | Build | Buy |
|---|---|---|
| Discovery and design | Requirements analysis, architecture, and solution design by internal staff or partners. | Selection, assessment, procurement, and solution design. |
| Initial solution | Product and engineering labor, testing, infrastructure, and required components. | License or subscription, implementation, installation, integration, testing, and required third-party software. |
| Customization | Engineering effort to create custom behavior, plus its future maintenance. | Configuration or customization fees and possible effects on upgrades. |
| People and adoption | Training, change management, user support, and specialist skills. | Training, change management, vendor or partner services, and user support. |
| Operations | Hosting and infrastructure, security, monitoring, reliability, support, and maintenance. | Recurring license or subscription, infrastructure not included in the price, support plans, and internal administration. |
| Lifecycle | Bug fixes, dependency and software lifecycle work, updates, maintenance, and future development. | Renewals, price tiers, upgrades, support, and integration maintenance. |
| Transition and exit | Migration, data movement, parallel running, decommissioning, and stranded assets. | Implementation and migration, coexistence, exit, data extraction, and decommissioning as applicable. |
| Usage and growth | Changes in compute, storage, network, and staffing as demand changes. | Changes in usage charges, license tiers, seats, transactions, or capacity as demand changes. |
Microsoft Learn puts the build-side scope plainly: “Evaluate the total cost of building a solution, including development resources, infrastructure, ongoing maintenance, and support.” Its build-versus-buy guidance also calls out functionality, timing, expertise, support, and updates (Microsoft Learn: Architecture strategies for getting the best rates from providers). Microsoft’s cost principles include technology choices, automation, acquisition, training, and change management (Microsoft financial modeling guidance).
For migration-related scenarios, AWS also identifies program setup, migration and modernization, temporary migration infrastructure, ramp-up, decommissioning, and stranded assets as business-case considerations (AWS business-case guidance).
4. Calculate and show the cash flows
Use a transparent structure for each scenario:
Scenario TCO over the chosen period = one-time implementation and transition costs + recurring operating costs over the period + exit or decommissioning costs − explicitly modeled residual value, if applicable.
This is a practical model structure, not a universal accounting standard. Keep any residual value explicit and supportable; do not use uncertain benefits to quietly reduce costs.
Sum costs over the shared period and show when they occur, by year or another useful interval. Include transition periods, overlapping systems, growth, and decommissioning where relevant. A time-phased view reveals whether one option has high early costs, higher ongoing costs, or costs concentrated near exit.
PC Slower Than It Used to Be?
A free scan shows the junk files, broken settings and background clutter dragging Windows down - then fixes them in one click.Free scan · Windows 10 & 11Outdated Drivers Are Slowing You Down
One free scan finds every outdated or missing driver and matches the right update for your exact hardware.Free scan · exact hardware matchIf timing materially affects the decision, add a net present value (NPV) or another finance-approved discounted cash-flow view alongside undiscounted totals. AWS business-case guidance describes NPV, ROI, payback, and multi-year cash-flow analysis as parts of a broader business case (AWS business-case guidance).
Best Value
- Brand: South-Western College Pub
- Product type: ABIS BOOK
- Business Analytics: Data Analysis & Decision Making
5. Expose assumptions and stress-test the estimate
Label estimates as estimates, not vendor quotes or guaranteed savings. Record the source and owner of each important input—for example, loaded labor costs, delivery effort, forecast usage, or contract pricing—and test plausible alternatives to the base case.
- Adoption or workload is higher or lower than forecast.
- Development takes more effort or launches later than expected.
- The required license tier, support plan, or implementation services change.
- Usage-based charges, seats, transactions, or capacity grow faster or slower than expected.
- More internal support or maintenance is needed than planned.
Compare the resulting totals and cash-flow timing, not just a single best-case number. Vendor rates, tiers, and contract terms can change, so verify current pricing and assumptions before making a purchasing decision.
6. Decide on fit as well as cost
The lower modeled TCO is not automatically the better choice if it fails a requirement or creates an unacceptable operational risk. Assess the cost result alongside the factors that determine whether the option can work in practice:
Recommended Free Tools
- Requirement fit and customization: Does a purchased solution meet the actual need, or is custom control important?
- Time to value: Account for development and testing for a build, and selection, integration, and deployment for a buy.
- Skills and ownership: Identify who will operate, secure, update, and support the solution, and whether those capabilities are available in-house.
- Support and lifecycle: Compare vendor support and updates with the obligation to maintain code, dependencies, and infrastructure internally.
- Growth and billing: Check how consumption, commitments, licensing, and workload growth affect future costs.
- Strategic value and risk: Keep material benefits and risks visible rather than treating a low cost total as proof that an option is strategically best.
If neither pure build nor pure buy meets the requirements well, assess a blended approach—for example, buying a core platform and building extensions. Apply the same shared outcome, time horizon, cost inventory, and assumption testing to that scenario.
Quick Recap
Model checklist
- Both scenarios meet the same documented capabilities, workload, and service levels.
- The time horizon and growth forecast are shared and explained.
- One-time, recurring, transition, and exit costs are visible by period.
- Build includes maintenance, infrastructure, and support; buy includes implementation, integration, and required support or components.
- Key assumptions have owners and sources, and plausible changes have been stress-tested.
- Cost is presented alongside fit, delivery timing, operational ownership, and risk.
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
