Custom software vs Odoo for SMEs in London in 2026: cost comparison

The verdict in three sentences

For a London SME whose processes fit the Odoo standard, the vendor stays unbeatable for the first three years thanks to fast go-live. Once you pass 40 to 60 users or your flows are atypical, the stack of licences + integration + custom work catches up with and then overtakes the cost of a bespoke build. The real trade-off is not the entry price but the total cost of ownership over five years and code ownership.

What Odoo really costs in 2026

Odoo is paid across three stacked lines: per-user subscription, initial integration by a partner, then annual maintenance. Typical 2026 orders of magnitude on the European market:

The trap sits in the "specific development" line: every gap from the standard costs man-days, and a version migration can break those adaptations.

Custom: the opposite cost structure

Custom flips the logic: a heavier upfront investment, then zero licences. 2026 orders of magnitude for a service or industrial SME in London:

Over five years, the absence of a per-user licence changes everything once headcount grows: each new colleague is free on the software side.

Mini case study

James, MD of a B2B distribution SME in London, has 45 users on his future ERP. Odoo Custom scenario: 45 × 37.50 EUR × 12 = 20,250 EUR/year in licences, plus 30,000 EUR integration, plus 4,000 EUR/year maintenance. Over five years: 30,000 + (20,250 × 5) + (4,000 × 5) = 151,250 EUR. Custom scenario: 75,000 EUR build, 15,000 EUR/year maintenance, 4,800 EUR/year hosting. Over five years: 75,000 + (19,800 × 5) = 174,000 EUR. Odoo wins by 23,000 EUR here. But if James scales to 80 users, the Odoo licence line jumps to 36,000 EUR/year and the total exceeds 220,000 EUR: custom then becomes the economical choice.

FAQ

At how many users does custom become worthwhile?

In 2026 the tipping point usually sits between 40 and 60 users for standard processes. Beyond that, the licence saving (300 to 450 EUR/user/year) funds the upfront gap within 3 to 4 years.

How long to deploy Odoo vs custom?

Standard Odoo deploys in 6 to 12 weeks, custom in 3 to 6 months. If timeline is your top constraint, Odoo keeps the edge.

Does custom cost more in maintenance?

Budget 10,000 to 20,000 EUR/year of custom maintenance versus 8 to 15 % of the project for Odoo, plus the version migrations every 1 to 2 years (5,000 to 20,000 EUR) that Odoo forces and custom does not.

Can we start on Odoo then move to custom?

Yes, and it is a common strategy: validate needs on Odoo for 18 to 24 months, then rebuild the differentiating modules in custom. Budget 10,000 to 25,000 EUR for data migration.

Who owns the data and code in each case?

With custom, you own 100 % of the source code and host your data wherever you want. With Odoo, the core stays under vendor licence; only your specific developments belong to you.

Let's scope your project. Give us your user count, your 3 critical processes and an indicative budget, and we will model the 5-year cost of both scenarios. Detailed quote within 48 h. WhatsApp +221 77 596 93 33.