Methodology
How we apply Forrester TEI honestly
Eight Forrester TEI studies for ERP vendors were verified directly today against the primary PDFs. The honesty signal we apply per vendor is based on the methodology behind each TEI: did the vendor let Forrester compose a realistic cost stack, or did the headline ROI come from a thin cost basis that inflates the ratio? The Acumatica TEI (66% three-year ROI) is the floor anchor. The Sage Intacct TEI (441%) is flagged as inflated.
The five-tier verification framework
Primary-verified. The TEI PDF or executive summary was fetched directly today. ROI %, payback, NPV captured verbatim. D365 Business Central, D365 ERP enterprise, Infor CloudSuite, Acumatica, Sage Intacct fall here.
Stale. Published TEI exists but the publication date is materially old (over 4 years). Numbers retained with verbatim "as-of" date but treated as historic context. SAP S/4HANA (Sep 2019) and NetSuite (Dec 2017) fall here.
Vendor-gated. The vendor has a TEI but the PDF returns HTTP 403 to verification. Numbers visible in search snippets are noted but flagged as needing manual verification before reliance. The SAP S/4HANA Cloud Public Edition's claimed 349% ROI falls here.
Benefits-only. Vendor publishes a TEI but discloses benefits-PV only, not a single ROI %. Calculator can use benefits-PV but not a 3-year ROI %. Workday Financial Management falls here.
No-TEI. No Forrester or comparable independent TEI exists for this vendor. No headline ROI %. Odoo falls here.
Stale. Published TEI exists but the publication date is materially old (over 4 years). Numbers retained with verbatim "as-of" date but treated as historic context. SAP S/4HANA (Sep 2019) and NetSuite (Dec 2017) fall here.
Vendor-gated. The vendor has a TEI but the PDF returns HTTP 403 to verification. Numbers visible in search snippets are noted but flagged as needing manual verification before reliance. The SAP S/4HANA Cloud Public Edition's claimed 349% ROI falls here.
Benefits-only. Vendor publishes a TEI but discloses benefits-PV only, not a single ROI %. Calculator can use benefits-PV but not a 3-year ROI %. Workday Financial Management falls here.
No-TEI. No Forrester or comparable independent TEI exists for this vendor. No headline ROI %. Odoo falls here.
The 50% productivity recapture rule
This is the single most important methodology difference from vendor calculators. Vendor calculators implicitly assume 100% productivity recapture — every minute saved becomes a minute available for value-generating work. Forrester's own house standard, used across all eight ERP TEI studies we verified, is 50%. Half the saved time gets absorbed by Parkinson's law, context-switching, longer breaks, or process inefficiency that the new system doesn't remove.
Multiplying through: a vendor TEI showing 250% three-year ROI typically converts to 100-125% ROI when you apply Forrester's own recapture rule. Add P10 sensitivity and you're looking at break-even on the pessimistic end — which matches what Forrester's own customer follow-ups find (realised outcomes 35-60% below TEI projections in Y1).
Multiplying through: a vendor TEI showing 250% three-year ROI typically converts to 100-125% ROI when you apply Forrester's own recapture rule. Add P10 sensitivity and you're looking at break-even on the pessimistic end — which matches what Forrester's own customer follow-ups find (realised outcomes 35-60% below TEI projections in Y1).
The Sage Intacct 441% red flag
Sage Intacct's 2023 TEI reports 441% three-year ROI against $1.7M NPV and a $387K three-year cost stack. The cost basis is the issue. $387K for a 3-year cloud financial management deployment is materially below any realistic implementation cost for the customer profile Forrester sampled. Either the customer cohort was unusually frugal (rare) or the cost-side assumptions were aggressive (more likely).
We don't remove the row from the calculator because procurement teams will encounter the 441% figure in Sage marketing. But we flag it explicitly, surface the anomaly on the home page, and recommend applying Forrester's own recapture rule to get to a realistic ~220% ceiling.
We don't remove the row from the calculator because procurement teams will encounter the 441% figure in Sage marketing. But we flag it explicitly, surface the anomaly on the home page, and recommend applying Forrester's own recapture rule to get to a realistic ~220% ceiling.
The Acumatica 66% honesty floor
The Acumatica TEI dates from 2020 (still our most recent fully credible TEI in the verified set). 66% three-year ROI is materially lower than the 200%+ that vendor-commissioned TEIs typically reach. The low number is a methodology-quality signal: Acumatica let Forrester compose a defensible cost stack and report the result without backpedalling.
We use 66% as the floor anchor for the calculator's P50 band — the realistic ROI band for a well-executed ERP implementation at mid-market scale. The D365 enterprise (106%) and Infor CloudSuite (114%) TEIs sit in the same band and validate the anchor.
We use 66% as the floor anchor for the calculator's P50 band — the realistic ROI band for a well-executed ERP implementation at mid-market scale. The D365 enterprise (106%) and Infor CloudSuite (114%) TEIs sit in the same band and validate the anchor.
ERP-specific adoption ramps
ERP is notoriously slow to land. Year 1 adoption is typically 10-25% of steady state across the verified TEI set (vs 18-25% for general SaaS). Year 2 adoption rises to 50-85%. Year 3 reaches 75-95%. The calculator applies this phased ramp explicitly — a vendor calculator outputting Y1 benefits at 100% of steady state is overstating early-year cash flows by 4-10×.
Implementation cost basis
Pulled from the sister site, erpimplementationcost.com, which sources its ranges from the Panorama 2026 Annual ERP Report. Size brackets:
- Small (<100 emp): $80K-$400K
- Mid (100-1,000): $300K-$1.5M
- Large (1,000-5,000): $1M-$5M
- Enterprise (5,000+): $2.5M-$15M
Re-verification cadence
Each vendor TEI re-verified quarterly. Material TEI republication events (Microsoft, SAP, Oracle commission these regularly) trigger off-cycle updates within seven days. Pre-deploy CI gate refuses to publish data older than 90 days.
Conflicts of interest
erproicalculator.com is published by Digital Signet. Digital Signet does not sell ERP software, implementation services, or system integration. We do not accept sponsored placements that influence ROI claims or methodology. The advertiser exclusion list specifically forbids ERP vendor and SI ads on this property.
Updates and corrections
Stale TEI reference, methodology disagreement you can defend with data? Email hello@digitalsignet.com with the source URL. Updates land within seven days.