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ROI comparison legacy modernization and continued operation

ROI Calculator: Modernization vs. Continued Operation

Rising maintenance costs or a one-time modernization? Compare total costs and find the right time to make the switch.

In brief

Break-even by maintenance band

At moderate maintenance of EUR 2,000 to 5,000 per month and a 10 to 15 percent rise, modernization break-even sits at 18 to 30 months. The calculator defaults, EUR 4,000 per month and 12 percent, fall in that band.

Compare legacy maintenance with a new build

ROI calculator

Modernization vs. continuing legacy

Does modernizing your legacy system pay off or is continuing it cheaper? Adjust the values to your situation.

Step 1 of 714%
4,000 €
500 €25,000 €

How the modernization break-even is built

The calculation follows six visible stages. All figures remain planning values until scope and assumptions have been reviewed.

  1. 1. Capture inputs

    The calculator records the visible project, volume, complexity and operating parameters selected on this page.

  2. 2. Add fixed components

    One-off investment and recurring operating components are added separately.

  3. 3. Apply multipliers

    Volumes, time values and rates are multiplied where the model converts effort or incidents into monetary effects.

  4. 4. Create the range

    The calculator applies its documented lower and upper uncertainty factors to the base result; ROI views keep investment and savings visible separately.

  5. 5. Round and calibrate

    Monetary result fields are rounded to the nearest whole euro. Public project-cost components are calibrated with the centrally maintained display factor.

  6. 6. Classify the result

    The result is shown as non-binding guidance. A binding quote requires scope, data, integrations, risks and acceptance criteria to be reviewed.

Included

  • Inputs shown in the calculator
  • Calculator-specific base values and factors
  • Displayed one-off and recurring result components

Not included

  • Requirements not selected in the calculator
  • Unknown data migration and third-party licence costs
  • Taxes, legal advice and a binding delivery commitment

Efficiency or discount factor: A central display factor of 0.7 is applied to public project-cost components to keep all calculators aligned with the currently reviewed pricing basis. It is not a customer-specific discount; customer-entered wages, revenues and existing operating costs are not reduced.

Why this is not a binding quote: The calculator cannot verify complete requirements, third-party dependencies, data quality, legal constraints or acceptance criteria.

Technical responsibility and review

Technical owner
Björn Groenewold
Role
Managing Director and software engineer
Expertise
Software development and software estimation
First published
Last technical review
Price basis
September 2026

Sample calculations & scenarios

Concrete project profiles with assumptions and indicative budgets—useful for internal alignment alongside the calculator.

Cost examples

All cost examples for this calculator

Legacy systems get more expensive every year. Skilled developers are harder to find, maintenance grows more complex, and security risks increase. This comparison of legacy and a new build shows when legacy modernization pays off against continued operation. At EUR 4,000 maintenance per month and a 12 percent rise, the case sits in the moderate band. Break-even is then 18 to 30 months.

Legacy maintenance rarely grows in a straight line. It often accelerates. More debt, more fragile workarounds, and fewer experts who still know the stack.

Security pressure adds to this. Old frameworks may stop getting patches. Requirements like GDPR or accessibility are hard to meet in outdated systems without disproportionate cost. Hidden line items sit in the software pain calculator.

Why Legacy Costs Grow Over Time

Skills Shortage

Developers for older technologies are becoming scarcer and more expensive. Hourly rates for legacy specialists rise 10–20% per year.

Security Risks

Outdated frameworks no longer receive security updates. Compliance requirements become increasingly hard to meet.

Technical Debt

Every workaround and patch adds technical debt. Changes take longer and carry more risk. The tech-debt score ranks that pressure and does not set a second break-even.

Typical Break-Even Timeframes

8–18 Months
High Legacy Costs
  • Maintenance > EUR 5,000 / month
  • Increase > 15% / year
  • High productivity gain
18–30 Months
Moderate Legacy Costs
  • Maintenance EUR 2,000–5,000 / month
  • Increase 10–15% / year
  • Phased migration
30+ Months
Strategic Modernization
  • Lower maintenance costs
  • Low increase rate
  • Long-term focus

Finance Your Investment: Leasing & Subsidies

The upfront spend can be spread over 72 months. Whether the rate sits below the legacy maintenance you stop paying is what the calculator shows with your figures. Terms are on the software financing page.

Whether a current KfW product or a German state programme fits the replacement is what the funding calculator checks. go-digital has ended, and Digital Jetzt ended on 31 December 2023. The catalogue span EUR 1,470 – 699,930 excl. VAT is the investment frame, not the monthly rate and not the saving.

FAQ

Modernization vs. Continued Operation

Break-even & Approach

When is legacy modernization worth it?

At moderate maintenance of EUR 2,000 to 5,000 per month and a 10 to 15 percent yearly rise, break-even sits at 18 to 30 months.

Above EUR 5,000 per month and a rise above 15 percent, the range shortens to 8 to 18 months. Strategic modernization with lower maintenance sits at 30 months or more. The table on this page splits the cases.

Why do legacy maintenance costs increase over time?

Legacy systems get more expensive due to. Fewer skilled developers available (Delphi, COBOL, etc.), growing technical debt, compatibility problems with new infrastructure, rising security requirements, and more workarounds for missing features.

What does productivity gain after modernization mean?

Modern software is faster, more stable, and easier to use.

Staff complete tasks in less time, downtime drops, and new features can be added faster. A typical productivity increase of 10–25% translates directly into saved working hours.

Do I have to modernize everything at once?

No.

We recommend a phased approach. Modernize the most critical modules first, use the Strangler Fig pattern for gradual migration, and run the old and new systems in parallel while phasing out the old one.

This limits risk and spreads the investment across budget periods.

What are the risks of modernization?

Key risks include incomplete requirements analysis, data migration issues, and underestimating complexity.

We reduce these risks through: a paid discovery phase, step-by-step migration, parallel operation, and automated testing. A 20% budget buffer is recommended.

Björn Groenewold – Geschäftsführer Groenewold IT Solutions

Calculate legacy modernization ROI

We advise on risks, phasing and ROI.

Book a call

Risks & Data

How accurate is the calculator?

The calculator gives a first estimate.

Actual legacy cost growth and modernization costs vary by technology, system complexity, and company size. For a reliable figure, we recommend a free initial consultation including a system review.

What happens if I don't modernize?

Without modernization, risks grow: maintenance costs rise, security gaps appear, qualified staff become harder to find, users grow frustrated, and the system falls behind the market.

The longer you wait, the more expensive the migration becomes.

Do I need to modernize the entire system at once?

No.

We recommend the Strangler Fig pattern: new modules are built alongside the legacy system and gradually replace it. This keeps operations running, limits risk, and lets you spread costs across budget periods. The modules with the highest maintenance costs are replaced first.

What happens to my existing data?

Data migration is part of every modernization project.

We review existing data structures, clean and convert the data for the new system, and make sure nothing is lost. Automated migration scripts and validation tests ensure a complete and accurate transfer.

How do I minimize risk during modernization?

Through gradual migration using the Strangler Fig pattern, a paid discovery phase to assess the current state, parallel operation of old and new systems during the transition, and automated testing and monitoring.

A 20% budget buffer is recommended. This reduces risk step by step and keeps you in control throughout.

ROI calculators

Inputs in the maintenance comparison

Which inputs move continued operation

Four checks: monthly maintenance, the yearly rise, outage risk, and the scope of the renewal.

  1. 1. Pick the maintenance band

    EUR 2,000 to 5,000 a month is the moderate band and leads to 18 to 30 months. Below that it can be shorter, above it longer.

  2. 2. Apply the rise only to the status quo

    10 to 15 percent a year makes continued operation more expensive. The calculator defaults sit at EUR 4,000 and 12 percent.

  3. 3. Keep outages apart from maintenance

    Downtime belongs in the baseline. Do not also book it as saved maintenance.

  4. 4. Read the renewal as an investment

    The catalog range is the investment frame, not the monthly rate and not the saving.

Typical pricing models (overview)

Comparison: typical pricing models for software and IT projects
ModelWhen it fitsBudget & flexibilityTypical risks
Fixed price (fixed scope)Clearly defined scope, stable requirements, repeatable delivery.Predictable total cost; little room for change without a change order.Scope creep leads to change orders or quality trade-offs.
Time & MaterialDiscovery, legacy, evolving requirements, or close collaboration.Maximum flexibility; budget transparent via hourly or daily rates.Without prioritisation, effort can grow—backlog and reviews matter.
Retainer / maintenance packageOngoing operations, updates, small features, and support.Agreed capacity per month; predictable follow-on cost.Large changes may still need a separate estimate.
Hybrid (milestone + T&M)MVP or phased releases with clear go-lives, then iterate.Core delivery fixed price; extensions on a time-and-materials basis.Define contractually what is in scope vs. extra work.

Calculators on this page provide indicative ranges; we choose the right model with you based on risk, scope, and planning horizon.

What determines the costs, and what comes next?

The ranges shown are indicative. For a binding quote we discuss scope, priorities and funding options in a free intro call. Many digitalization projects qualify for grants – try our funding calculator.

Browse all cost calculators, explore services and typical solutions. Questions about modernization ROI? Contact us.

After using the modernization ROI calculator, validate assumptions in a short intro call.

What we align in the call

  • Scope, risks, and funding options
  • Milestones and documented exclusions
  • Transparent quote without hidden line items

Costs for modernization ROI in context

  • Scope, risk, and quality expectations drive the range
  • Include operations, maintenance, and grants
  • Dedicated contacts and short paths from East Frisia

Browse all cost calculators in the costs overview.