If you make things and you are outgrowing spreadsheets, someone will eventually tell you that you need an ERP. It is worth knowing what that word actually commits you to before you agree.
The short version
MRP plans and runs production. It answers what to make, what to buy, when, and what it cost. ERP does that too, and then adds finance, HR, payroll, CRM and whatever else the vendor has acquired.
ERP is not a better MRP. It is a wider system, and width has a price that is paid in implementation time, consultant days and the number of people who have to change how they work.
What ERP actually means
Enterprise Resource Planning is one database that every part of a business writes to. One record for a customer, one for a part, one for an employee, shared by sales, production, purchasing, finance and HR. That is the whole idea, and it is a good one. The alternative, which most small manufacturers live with, is a separate record in each system and a person quietly reconciling them.
The name is historical rather than descriptive. Material Requirements Planning came first and answered one question: given what we have promised to make, what do we need to buy and when. Manufacturing Resource Planning added capacity, costing and the shop floor. ERP kept going and added everything else a company does, which is why the term now covers products with very little in common. If you want that older distinction set out properly, we cover MRP and MRP II separately.
What matters for a decision is not the acronym. It is scope. ERP is defined by breadth rather than by quality, and breadth is the thing you are being asked to pay for.
What each one actually covers
| Area | MRP | ERP |
|---|---|---|
| Bills of materials and routing | Yes | Yes |
| Material planning and purchasing | Yes | Yes |
| Works orders and shop floor | Yes | Usually, sometimes as a module |
| Stock and warehouse | Yes | Yes |
| Invoicing and accounts receivable | Often | Yes |
| General ledger and statutory accounts | No, integrates instead | Yes |
| Payroll and HR | No | Yes |
| Typical implementation | Weeks | Months to years |
The honest case for and against
We sell MRP, so read the following as an interested party trying to be fair rather than as neutral advice.
What ERP genuinely does better
- One database means no integration to maintain and nothing to reconcile between systems. If your operations and your ledger are permanently out of step, that is a real problem and ERP solves it properly.
- Consolidation across companies, sites and currencies is native rather than bolted on.
- Reporting spans everything. A margin figure can include overhead, payroll and finance costs without anyone exporting a spreadsheet.
- There is one vendor to hold responsible when something does not work.
What it costs you
- Implementation is a project rather than an installation, and somebody senior has to own it for its whole length.
- Breadth means compromise. The manufacturing module of a general ERP is rarely as strong as a system that does only manufacturing, and its accounting is rarely as strong as a dedicated accounting package.
- Changing anything afterwards touches more of the business, so change gets slower and more expensive as time passes.
- You replace tools your staff already know. Each one is a retraining cost and a source of resistance.
None of that makes ERP wrong. It makes the choice a question of scope and spare capacity rather than a question of software quality.
When a workshop genuinely needs ERP
There are real cases. Be honest about whether you are in one.
- You run multiple legal entities, consolidate accounts across them, or report in more than one currency.
- You have an in-house finance team who need the ledger and the operations in one database rather than integrated.
- You are large enough that a dedicated implementation team and a six figure budget are normal, not frightening.
When you almost certainly do not
- You are under about fifty people and your accountant is happy in Xero or Sage.
- Your actual problem is that you do not know what stock you hold, what a job cost, or which batch went to which customer.
- Nobody in the building has time to run a twelve month project on top of their day job.
That last point sinks more ERP projects than any technical failing. The system is fine. The workshop simply never had the spare capacity to implement it.
Most UK workshops that think they need an ERP need production visibility, traceability and honest job costing. That is MRP, and it takes weeks rather than quarters.
What implementing one actually involves
Most of the difficulty is not technical. A project runs roughly through the stages below, and the expensive parts are the human ones.
- Deciding how you actually work. An ERP forces you to write down processes that currently live in people’s heads. Disagreements that were survivable become blocking.
- Cleaning the data. Part numbers, bills of materials, supplier records and stock balances all have to be right before they move. This is usually the longest stage and it is almost always underestimated.
- Configuration. Someone maps your processes onto the software’s assumptions. Where the two disagree you either change how you work or pay for customisation, and customisation is what makes later upgrades painful.
- Training and parallel running. Two systems and twice the work, for as long as it takes people to trust the new one.
- Go live, and the dip after it. Output usually falls before it improves. Plan for that rather than being surprised by it.
Projects rarely come apart because the software could not do the job. They come apart because nobody had the capacity to do stages one and two properly while also shipping orders. That is worth being honest with yourself about before signing anything.
The middle path most people actually want
Run MRP for the making, keep your accountant in the accounting package, and connect them. Brytebuild pushes invoices, bills and COGS journals into Xero or Sage, and pulls Xero payments back for reconciliation. Your accountant keeps the tool they know. You get the operational side you were missing.
We deliberately do not run an internal general ledger. Building a worse version of Xero would help nobody.
How to decide in an afternoon
- Write down the three things going wrong this month. If they are all production, stock or traceability, you want MRP.
- Ask your accountant whether the current accounting setup is a problem. If it is not, do not replace it.
- Ask who will run the implementation and when. If the answer is nobody and never, pick the smaller system.
If that lands on MRP, our feature list sets out exactly what is included at each plan, and the industry pages cover the problems we hear most often in each sector.
If you are already comparing named systems rather than categories, the comparison pages set out where we differ from each of them. And RSA Customz, a custom metalwork job shop, run on two parts of Brytebuild and nothing else, which is a fair picture of what starting narrow looks like in practice.