Big bang vs. phased rollout: two contrasting approaches to an ERP project
The “big bang” deployment
This approach involves launching the new system across all departments—sales, finance, HR, and more—at the same time. On a set date, all business processes switch over to the new ERP in one go. The old system is shut down and replaced without a prolonged transition phase.
In return, this method requires thorough preparation upfront: all modules must be fully configured, tested, and validated before go-live. From that day forward, teams must be ready to operate exclusively within the new environment—with no safety net.
Phased deployment (or rollout by stages)
With this approach, the ERP is implemented step by step, either by department or by functional module. The old system continues to run in parallel while each part is migrated, tested, and adopted. This method allows for better user support, ongoing adjustments, and easier corrections in case of unforeseen issues. It’s also more flexible for incorporating feedback from the field.
On the downside, this approach requires a longer, more structured project management effort with dedicated resources.
Benefits and risks — what each approach really entails
Big bang: when efficiency becomes a high-stakes gamble
With a big bang deployment, you’re guaranteed the promise of immediate efficiency. But that speed comes at a cost and brings its share of drawbacks.
Advantages of the “big bang” deployment
- Quick wins: once deployed, the new ERP is fully operational for everyone. Your teams gain a unified view and centralized control.
- Overall consistency: one system, one database, clear governance. The big bang approach eliminates duplicates and temporary interfaces.
Risks of the “big bang” deployment
- No safety net: if an issue arises, the entire business slows down.
- High emotional and operational pressure on teams: the sudden switch can cause stress, especially if preparation is lacking.
- Difficulty anticipating everything: the risk of critical errors or blockages remains high and can disrupt operations if no backup plan is in place.
Phased rollout — securing change at the cost of a longer project
This approach emphasizes caution and adaptability but requires more resources over time.
- Risk reduction: each phase acts as a test for the next. You can correct, adjust, and gather user feedback along the way.
- Better adoption: teams have time to train, experiment, and embrace the tool at their own pace. The change is better received.
- Long-term management complexity: often involves temporarily maintaining the old system for certain components, managing interim interfaces between modules or tools, and carefully steering the project to maintain overall consistency throughout the transition.
How to choose the right approach?
The choice of ERP deployment method depends on the unique constraints, resources, and goals of each company. We’ve outlined the key criteria to help guide your strategy.
Internal company criteria — size, complexity, digital maturity
If you’re a small organization with simple processes and limited interdependencies, a full-scale, big bang deployment might be the faster option. Conversely, for a multi-site company, it’s usually wiser to proceed step by step.
Digital maturity also plays a role: if your teams are already comfortable with digital tools, adoption will be smoother—even with a big bang approach. It’s worth noting that digital maturity refers to how well a company integrates and adapts to digital technologies.
Available human and technical resources
As mentioned earlier, with a big bang deployment, most of the work happens upfront, so teams will be heavily engaged during that period. In contrast, a phased rollout spreads the effort out over time but requires sustained commitment. Also, consider your capacity to maintain two systems running in parallel during the transition phase, which may demand additional technical resources.
External constraints — deadlines, budget, mergers/acquisitions, regulatory deadlines
Tight deadlines? Or a strategic milestone (merger, audit)? In these cases, a big bang deployment is often the smarter choice. On the other hand, if your budget is spread over time or your operations are sensitive to interruptions, it’s safer to secure the implementation in stages—that is, progressively.
What if the best answer is a hybrid approach?
There’s no one-size-fits-all model for a successful ERP deployment — every organization has its own levers. Depending on your company’s actual needs, a hybrid approach that combines both methods is becoming increasingly popular.
Mixed scenarios — critical modules deployed in big bang, secondary modules staggered
In this scenario, the key system modules are rolled out first, while less urgent features are integrated later. This allows essential tools to be activated quickly for smooth business operations, while maintaining flexibility for the rest of the project.
Real-world examples (industries or contexts suited to this approach)
- An industrial company
A manufacturing SME chooses to activate modules related to production, inventory management, and purchasing from the start to secure its supply chain. HR management and preventive maintenance, which are less urgent, are integrated a few months later. - Service company
A consulting firm launches its ERP with billing, project management, and time tracking modules to monitor profitability from day one. The CRM, document management, and HR tools are integrated later, once key processes are stabilized. - E-commerce player
An online store prioritizes integrating its product catalog, order processing, and logistics to ensure sales continuity. Marketing automation, customer loyalty tools, and advanced reporting are added gradually based on needs.
The ERP integrator — a strategic partner to choose and succeed in your deployment
Implementing an ERP, whether all at once or in phases, involves critical decisions for the company. These are not just technical choices but also organizational, human, and strategic challenges. To gain clarity and build a tailored roadmap, it’s best to have support. That’s where an experienced integrator can make all the difference and become a true ally.
From the very start of the project, the integrator helps you analyze your context: organization, business constraints, internal resources, urgency of the change, and more. Their role is to provide a realistic assessment—without idealizing or exaggerating—to select the deployment method that best fits your needs.
The integrator doesn’t just deploy modules—they work with you to design a tailored deployment plan that considers your priorities, capacities, and deadlines. They anticipate interdependencies, critical phases, and key risk areas to build a sustainable timeline.
A successful deployment doesn’t end on go-live day. The ERP integrator supports you throughout the project with:
- Rigorous testing to minimize errors during the switch
- Targeted training to help teams become autonomous quickly
- Change management support, essential to get users on board with the new system and reduce internal friction
There’s no one-size-fits-all answer to the “big bang” versus phased rollout question. Every company has its own constraints, priorities, and capacity to manage change. The right approach is the one that fits your reality—not a fixed model. At Captivea, we believe that the success of an ERP project depends as much on a well-configured solution as on a carefully planned deployment strategy. That’s why we support our clients in building a realistic plan tailored to their context and sustainable in the long run.
Need clarity on the right approach for your company? Let’s discuss your context and challenges, and build a realistic, sustainable, and tailored ERP deployment plan.