How do you calculate forecast accuracy?

Divide demand that fell within forecast tolerance by total actual demand and multiply by 100. With 9,200 units within tolerance out of 10,000 total demand, forecast accuracy is 92%.

What is a good forecast accuracy in manufacturing?

It varies by demand stability, but 80-90% at the SKU-family level is common for discrete manufacturers, with high-volume runners often above 90%. The 92% here is solid; intermittent or new-product demand may run far lower.

What is the difference between forecast accuracy and forecast error?

Accuracy is the share of demand you got right; error (often MAPE) is the average percentage miss. They are complements — higher accuracy means lower error. This calculator reports accuracy and its gap to your target rather than a MAPE figure.

What does a negative gap to target mean?

A negative gap means you fell short of your target accuracy. Here actual accuracy is 92% against a 90% target, so the gap is +2 points above target — a positive result. A -2 would mean you missed the target by two points.

How does forecast accuracy affect safety stock?

Lower accuracy forces higher safety stock to cover demand variability. Improving from, say, 85% to 92% accuracy lets you carry less buffer for the same service level, freeing working capital tied up in inventory.

Should I measure forecast accuracy at SKU or family level?

Both. Family-level accuracy looks better because errors offset, while SKU-level reveals the real planning pain. A 92% family number can hide individual SKUs at 60%, so always drill down before declaring the forecast healthy.

ERP & MRP Planning calculator

Forecast Accuracy Calculator

Forecast accuracy measures how much of actual demand fell within the tolerance band your forecast predicted, expressed as a percentage of total demand. It is the metric that tells demand planners whether MRP is being driven by numbers worth trusting, and it directly governs how much safety stock and capacity buffer the plant has to carry. Supply chain and S&OP teams track it period over period to know whether forecasting is improving or quietly degrading. A forecast that misses consistently forces the shop to absorb the error with inventory, expedites, or missed shipments.

What this calculator does

Calculate forecast accuracy from demand that landed within tolerance versus total actual demand.
a demand planner needs to quantify forecast quality for a product family
It computes the share of total actual demand that landed within forecast tolerance and compares it against your accuracy target.

Formula used

Forecast accuracy = demand within forecast tolerance ÷ total actual demand × 100
Gap to target = target forecast accuracy - actual forecast accuracy

Inputs explained

Demand within forecast tolerance:
Total actual demand:
Target forecast accuracy:

How to use the result

Use it at the close of each demand period to score the forecast and report the gap to target in your S&OP review.
A single accuracy percentage hides direction and pattern — it does not tell you whether you over- or under-forecast, and it can look healthy while masking large errors on a few high-value SKUs.

Current U.S. benchmarks

Manufacturing hourly earnings average $30.27 (BLS, Jun 2026), up 4.4% from a year earlier. Median machinist pay is $28.24/hr (OEWS 2025), with state medians on each state page. Manufacturers have 529k open positions nationally (BLS JOLTS).
U.S. manufacturing runs at 75.6% of capacity (Federal Reserve, May 2026). New factory orders are up 2.3% year over year (Census).

Common questions

How do you calculate forecast accuracy? Divide demand that fell within forecast tolerance by total actual demand and multiply by 100. With 9,200 units within tolerance out of 10,000 total demand, forecast accuracy is 92%.
What is a good forecast accuracy in manufacturing? It varies by demand stability, but 80-90% at the SKU-family level is common for discrete manufacturers, with high-volume runners often above 90%. The 92% here is solid; intermittent or new-product demand may run far lower.
What is the difference between forecast accuracy and forecast error? Accuracy is the share of demand you got right; error (often MAPE) is the average percentage miss. They are complements — higher accuracy means lower error. This calculator reports accuracy and its gap to your target rather than a MAPE figure.
What does a negative gap to target mean? A negative gap means you fell short of your target accuracy. Here actual accuracy is 92% against a 90% target, so the gap is +2 points above target — a positive result. A -2 would mean you missed the target by two points.
How does forecast accuracy affect safety stock? Lower accuracy forces higher safety stock to cover demand variability. Improving from, say, 85% to 92% accuracy lets you carry less buffer for the same service level, freeing working capital tied up in inventory.

Last reviewed 2026-05-12.