What it means
Imagine a company making bicycles. To build 1,000 bicycles it needs 1,000 frames, 2,000 wheels, and many smaller parts, each with its own lead time (the time suppliers take to deliver).
MRP calculates these needs automatically and works backwards from the delivery date to decide when each order should be placed. The system has three main inputs.
The master production schedule says what will be made and when, the bill of materials lists every component in each product, and the inventory records show what is already in stock or on order. MRP combines them to produce a list of what to buy or make.
For finance, MRP matters because inventory ties up cash. Holding too much stock costs money in storage, insurance and the chance of becoming obsolete, while holding too little can stop production and delay sales.
A good plan balances these costs and smooths cash needs. MRP is only as good as its data.
If the bill of materials is wrong, stock counts are out of date or the sales forecast is poor, the plan will be wrong too. Many firms invest in regular stock counts and in clean product data for this reason.
Over time, MRP developed into broader systems that include capacity, labour and finance, often called manufacturing resource planning and enterprise resource planning. Modern software links purchasing, production and accounts so that planning decisions flow into budgets and cash forecasts.
Be aware that the same letters are used for other terms in different industries, such as maximum retail price in some countries. In a finance and operations context, material requirements planning is the usual meaning.
In practice
Real-world examples.
Example
A furniture maker plans to build 400 tables next month. The MRP system multiplies the number of tables by the parts in each, subtracts stock, and recommends orders for timber and screws with the right lead times. The purchasing team places the orders the same day, so the timber arrives before the assembly line needs it.
Example
A bakery chain uses MRP-style planning for ingredients across 30 shops. It forecasts demand for each product and orders flour and butter so deliveries arrive just in time. Waste falls by a noticeable amount, which improves gross margin. Store managers also spend less time counting stock by hand.
Example
A finance manager at an electronics company uses MRP output to forecast cash needs for purchases. The system shows that $2,500,000 of component orders will fall due in the next quarter. She arranges a short-term credit line before the peak, so the company can pay suppliers on time without disrupting other spending.
Formula
Calculation
Net Requirement = Gross Requirement - On-Hand Inventory - Scheduled Receipts + Safety Stock
Suppose a factory needs 5,000 units of a component for next month's production. It has 1,200 units in stock, 800 more already on order, and wants a safety stock of 500 units. Net Requirement = 5,000 - 1,200 - 800 + 500 = 3,500 units. At $12 per unit, the purchase order is 3,500 x 12 = $42,000. The safety stock is added because it is a buffer that must be rebuilt, and without it the factory would order only 3,000 units and risk running short if a delivery were late.Case study
Seen in the real world.
Calder Bikes is an illustrative, fictional manufacturer that kept 90 days of components in stock because past shortages had stopped production. Its inventory ran to $3,000,000, tying up cash that the business needed.
After introducing an MRP system and cleaning up its product lists, the planners trusted the schedule enough to cut stock to 45 days. Inventory fell to $1,500,000, freeing $1,500,000 of cash.
There were two weeks of teething troubles when a supplier delivered late, and the line stopped for one shift. The illustrative lesson is that MRP releases cash only when the data and supplier reliability can be trusted, so safety stock should come down gradually. The planners now review supplier delivery records each month before deciding the next reduction.
Watch out
Common mistakes.
- Feeding the system poor data, when errors in stock counts or product lists produce wrong orders.
- Cutting safety stock too fast, when suppliers may still deliver late.
- Treating MRP as a purchasing tool only, when it also affects cash flow, production scheduling and the value of inventory shown on the balance sheet.
Questions
People also ask.
What does MRP stand for?
In operations and finance it usually means material requirements planning, though in some countries the letters stand for maximum retail price.
How does MRP help cash flow?
By timing purchases to production needs, it reduces excess stock and the cash tied up in it, and it gives finance an early view of upcoming supplier payments.
What is a bill of materials?
It is the list of all the parts and quantities needed to make one unit of a product, and MRP multiplies it by the planned production quantity to find total needs.
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