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ERP Implementation Effort Estimator: Consulting Days, Cost and Duration

Before vendors present proposals you need your own view of how many consulting days a rollout takes. This estimator builds the number bottom-up from modules, sites, integrations, training and the customisation share, so you can challenge a quote that looks too thin or too thick.

Your numbers

modules

Finance, purchasing, sales, inventory, production planning, quality, service and so on.

days

Configuration, workshops, test and documentation for a standard module.

sites
15 %

From your fit-gap result.

interfaces

EDI, CRM, webshop, MES, banking, e-invoicing, CAD/PLM.

days
users
people
EUR

Your results

Total consulting days
391.29
Services cost
EUR 371,723
Core configuration days
192.5
Each additional site adds about 25 percent of rollout effort.
Customisation days
57.75
Custom work costs roughly twice the effort of configuring the same requirement.
Integration days
70
Training and change days
20
Project management days
51.04
Calendar duration
4.9 months
Assumes 16 billable days per consultant per month.

Rule-of-thumb model for early budgeting. Customer-specific scope, data quality and partner experience move real effort materially. Obtain a fixed-scope proposal before committing budget.

Save results:

Total consulting days vs customisation share

Sweeps Requirements needing customisation from 0 to 60, holding your other inputs fixed.

Optional proposal review

Share a partner proposal and we will compare it with a bottom-up estimate and list open assumptions. No obligation.

Optional. The tool and every export work without this. No spam.

How to use it

Start with the modules you intend to go live with in the first wave, not the whole product catalogue. Enter the percentage of requirements your fit-gap analysis says need customisation. Adjust the team size to see how calendar duration changes: more consultants shorten the timeline but rarely in a straight line because client key users are the real bottleneck.

  • Use first-wave modules only
  • Take the customisation share from a fit-gap, not a guess
  • Count every integration, including bank and e-invoicing
  • Keep client key user availability in mind

How the model works

Core days equal modules times base days, scaled by 25 percent for each additional site to reflect local master data, tax and workshops. Customisation is priced at twice its configuration equivalent. Integrations and training are added linearly, then 15 percent project management is applied to the sum. Duration is total days divided by team size times 16 billable days per month.

Reading the output

Compare total days with the partner proposal. A quote far below your estimate usually hides assumptions such as client-delivered data migration or limited testing. A quote far above often prices custom work generously. The chart shows how sensitive the programme is to customisation: every extra 10 points of customised requirements adds a visible block of effort.

Common mistakes

Teams underestimate data migration and testing, assume key users are fully available, and treat integration as a one-off task rather than design, build, test and cutover. Another mistake is applying one day rate to all roles. If senior architects do much of the work, use a higher blended rate.

Frequently Asked Questions

Is this specific to one ERP?

No. The structure suits abas, proALPHA, IFS, Exact, Priority, Visma and similar mid-market systems. Tune base days per module to the vendor's typical effort for your industry.

Why is customisation doubled?

Custom work needs specification, development, test, documentation and upgrade regression, while configuration needs only setup and test. Two times is a common planning factor, not a law.

Does it include data migration?

Partly, through the base module days. For heavy legacy data, use the data migration effort calculator and add its hours to the total.

Can I use it for a rollout to extra plants?

Yes. Enter only the modules being rolled out and set sites to the number of new entities. The template effort is usually lower, so reduce base days per module.

Netray can review a partner proposal against this kind of bottom-up estimate and flag where scope or testing looks thin.

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