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Methodology

How the ROI calculator computes results

Every formula, every default, every guardrail. If a value is not a fact from your data, it is labeled as an assumption — and the methodology tells you how to validate it.

Last updated 2026-05-18

Seven-step process

From spreadsheet to defensible business case

  1. Step 1. Establish a defensible baseline

    Collect today's state for every driver — hours per task, close cycle time, invoices per AP clerk, current DSO, vendor spend by category. The baseline must be agreed to by the process owner before any benefit is modeled.

  2. Step 2. Select a small set of value drivers

    Pick three to five drivers tied to outcomes leadership has already prioritized. Common drivers: labor efficiency, close acceleration, AP automation, DSO improvement, legacy systems retired, headcount avoidance.

  3. Step 3. Apply the formula for each driver

    Labor savings = hours saved × fully loaded rate. Close acceleration = hours per close × closes/year × rate. AP = (minutes/60) × invoices/year × rate. DSO cash = (revenue/days) × DSO days improved. Headcount avoidance = avoided FTE × fully loaded cost. Document the inputs alongside the output.

  4. Step 4. Apply realization and adoption discounts

    Multiply the raw benefit by a productivity-realization percent so that adoption risk and partial capture are visible. Treat realization itself as an assumption to be validated.

  5. Step 5. Separate one-time from recurring costs

    Model implementation services, internal project time, training, and one-time hardware as one-time. Subscriptions, support, and ongoing internal labor are recurring. Payback uses one-time investment; NPV uses both.

  6. Step 6. Compute ROI, payback, and (optionally) NPV

    Simple ROI = annual net value / annual cost. Payback = one-time cost / annual net value. NPV discounts three years of net value at WACC and subtracts the one-time implementation cost.

  7. Step 7. Stress test and document

    Run downside, base, and upside scenarios on the largest drivers (typically adoption, hours saved, DSO improvement). Record every assumption with an owner and a validation plan.

Run the numbers in the Technology ROI Calculator. The full bibliography is on the sources page; definitions are in the glossary.

Value drivers

The benefit formulas

Labor efficiency savings

Formula: hours saved per year × fully loaded hourly rate. When modeling a percentage productivity lift across a team, multiply by a separate realization percent so that not-all-time-saved-becomes-cash stays visible.

Close acceleration savings

Formula: hours saved per close × closes per year × fully loaded rate. Cycle-time framing and benchmarks come from APQC.[1]

AP invoice processing savings

Formula: (minutes saved per invoice ÷ 60) × invoices per year × hourly rate. Definition of what to include in invoice processing cost from IOFM.[2]

Headcount avoidance

Formula: avoided hires × fully loaded cost per employee. Only model this when the organization would otherwise hire and the freed capacity is real.

Cash flow acceleration from DSO improvement

Formula: (annual revenue ÷ days in year) × DSO days improved. The result is a one-time cash release — not a recurring annual savings. Definitions and framing from JPMorgan.[3]

Day-count option: the calculator defaults to 365 calendar days for accounting consistency. Set the basis to 260 if your finance team uses working days. Document which choice you made and why.

Vendor spend savings

Formula: annual vendor spend × spend-improvement percent.

Legacy systems retired

Formula: legacy software + server/infrastructure + IT support reductions − new system recurring cost. Represents annual net savings from consolidating systems.

Risk reduction

Tracked as a qualitative score by default. If you convert risk to dollars, use a conservative expected-loss proxy, keep the proxy explicit, and document the rationale.

Decision metrics

ROI vs payback vs NPV

Simple ROI

Compares total annual benefits to total annual costs. Useful as a quick screen but hides timing differences and one-time implementation costs.

Payback period

Estimates how long annual net value takes to recover the one-time implementation cost. Easy to explain; ignores value after payback. Recurring costs are modeled annually within the value drivers (as part of system consolidation net savings); the one-time implementation cost is separate so payback reflects upfront investment.

NPV (optional advanced mode)

NPV discounts future cash flows using a chosen rate. The calculator uses WACC as the default discount-rate concept because it is a common proxy for cost of capital.[4]

Guardrail: pick a discount rate that matches your company and project risk profile. When in doubt, treat the discount rate as an assumption and validate it with finance leadership.[5]

In this calculator, 3-year NPV discounts three years of annual net value and then subtracts the one-time implementation cost.

Scope

What is included, what is excluded

Included: measurable labor savings, cycle-time reduction that produces real capacity, headcount avoidance when justified, vendor spend reductions, legacy system retirement savings, and working capital cash acceleration.

Excluded by default: revenue uplift, strategic-value narratives, and highly speculative benefits. If you add them, document evidence and treat them as assumptions.

Sources used on this page

  1. APQC: Cycle time to perform monthly close

    Benchmark definitions and cycle-time framing for the close process. Specific benchmark values vary by dataset and may be gated.

    Accessed 2025-12-12

  2. IOFM: Determining the cost to process an invoice

    Methodology guidance for calculating invoice processing cost and what to include. Some details may require a subscription.

    Accessed 2025-12-12

  3. JPMorgan: DSO and DPO: how they can improve your cash flow

    Definitions and practical framing for receivables and payables cycle metrics and cash flow impact.

    Accessed 2025-12-12

  4. Aswath Damodaran, NYU Stern: WACC central

    Overview and related references for WACC and cost of capital estimation.

    Accessed 2025-12-12

  5. Aswath Damodaran, NYU Stern: Cost of Capital by Country (short, PDF)

    Reference material for thinking about cost of capital inputs. Use a WACC that matches your company risk profile.

    Accessed 2025-12-12

Next step

Next: Technology ROI Calculator

Product-agnostic interactive ROI model: value drivers, payback, optional NPV with transparent assumptions.

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