MRO (Maintenance, Repair & Operations)
The supplies, parts, and consumables a maintenance team uses to keep operations running — separate from raw materials that become finished products.
Definition
MRO stands for Maintenance, Repair, and Operations. It refers to the goods a business consumes to keep itself running, as opposed to the raw materials that get turned into finished products. Spare bearings, lubricants, hand tools, safety gloves, light bulbs, cleaning supplies, and PPE are all MRO. In accounting terms MRO is usually expensed rather than capitalized.
Why MRO is hard to control
MRO inventory tends to sprawl. Items are low-value individually but high-value in aggregate. Multiple people order from multiple suppliers, often without checking stock first. Critical spares hide in personal toolboxes, while obsolete parts gather dust. Most plants discover during their first real audit that MRO inventory is 20–40% larger than the system shows.
How a CMMS helps
A CMMS with parts and inventory tracks on-hand quantity, reorder points, supplier and cost, and — critically — which assets each part fits. When a technician closes a work order and consumes a bearing, stock decrements automatically. Reorder alerts fire before stockouts trigger emergency overnight shipping. Vendor performance becomes measurable.
MRO best practices
Standardize on as few part numbers as possible; consolidate suppliers to negotiate better terms; lock the storeroom and require check-out; do a quarterly cycle count rather than an annual full inventory; and review the slow-moving list every six months to write off true obsolescence.
Is MRO the same as spare parts?
Spare parts are a subset of MRO. MRO also covers consumables, tools, and operating supplies that are not strictly 'parts'.
How much MRO inventory should I carry?
Enough to cover critical-spare lead times for assets where downtime is expensive, and no more. Anything else ties up cash without reducing risk.