Direct Material Price Variance Calculator
From standard price, actual price and actual quantity, compute the material price variance (favourable or unfavourable).
輸入資料
計算結果
重點速覽：Price variance = (standard price - actual price) x actual quantity purchased. Positive = favourable (F, bought cheaper than standard); negative = unfavourable (U, paid more). It reflects the purchasing stage (negotiation, supplier, market price). WARNING: Covers only price variance, not usage variance; depends on a reasonable standard; F is not always good (could be lower quality), U not always buyer's fault (market rise). Interpret with context. Education, not advice.
計算公式
價格差異 = (標準單價 − 實際單價) × 實際採購數量。
正值為有利差異 (實際較便宜)，負值為不利差異 (實際較貴)。
$$\text{Price Variance} = (\text{Std Price} - \text{Actual Price}) \times \text{Actual Qty}$$使用說明
- Enter the standard unit price.
- Enter the actual unit price and quantity purchased.
- View the price variance — positive is favourable, negative unfavourable.
直接材料價格差異計算範例 (標準單價 HK$10)
| 實際單價 | 實際採購數量 | 價格差異 | 有利/不利 |
|---|---|---|---|
| HK$9 | 500 單位 | HK$500.00 | 有利 (F) |
| HK$11 | 500 單位 | −HK$500.00 | 不利 (U) |
| HK$11 | 800 單位 | −HK$800.00 | 不利 (U) |
價格差異 = (標準單價 − 實際單價) × 實際採購數量。實際較便宜為正 (有利)、較貴為負 (不利)；差異隨採購量放大。
理財情境案例
案例一：計算直接材料價格差異
某工廠某原料的標準單價 (事前預算設定) 為 HK$10，本期實際以 HK$11 的單價採購了 500 單位。
套用公式：價格差異 = (標準單價 − 實際單價) × 實際採購數量 = (10 − 11) × 500 = −1 × 500 = −HK$500。
結果為『負值 −HK$500』,代表這是一個『不利差異 (unfavourable)』— 因為實際買得比標準貴 (每單位多花 HK$1)，共 500 單位就多花了 HK$500 成本。反之，若實際單價降到 HK$9，價格差異 = (10 − 9) × 500 = +HK$500，即『有利差異 (favourable)』,替公司省了 HK$500。
案例二：價格差異的正確解讀與責任歸屬
看到差異的正負後，切勿直接下『採購做得好/壞』的結論 —『有利/不利』只是純粹從成本高低定義的會計術語，不等於價值判斷。一個不利差異可能只是因為原材料市場價格普遍上漲 (非採購失職)；而一個有利差異，也可能是採購了品質較低、較便宜的替代品所致 — 這種『帳面有利』反而可能推高後續的用量差異或退貨，得不償失。
此外，本計算器只算『價格差異』這一半，完整的直接材料差異分析還需計算『用量差異 (usage/quantity variance)』— 即比較實際用量與標準應用量的偏差。價格差異反映『買得貴不貴』(採購環節)，用量差異反映『用得省不省』(生產環節)，兩者拆開才能對症下藥。
實務提醒：(1) 差異數字的參考價值取決於『標準單價』是否合理 — 標準過時或不切實際，差異就會失真；(2) 若差異長期偏向某一方向 (例如年年不利)，往往是『標準需要重新檢討』的訊號，而非採購一直失職；(3) 差異分析務必結合實際業務背景 (市場行情、供應商變動、品質取捨) 解讀。本站另有『邊際成本計算器』與『貢獻邊際計算器』可搭配理解成本結構。
常見問題
How do I tell favourable from unfavourable?
Under the formula (standard - actual) x quantity: positive = favourable (F), negative = unfavourable (U). Logic: when actual price < standard, you bought cheaper and saved — favourable; when actual > standard, you paid more — unfavourable. But 'favourable/unfavourable' is a pure cost-accounting term, not a value judgement of good/bad — a favourable may come from lower-quality material; an unfavourable may be a market price rise. Investigate the cause, don't just read the sign.
How is price variance different from usage variance?
They are the two parts of total direct-material variance, splitting cost deviation into 'bought dear or cheap' and 'used sparingly or wastefully'. Price variance (this tool) measures the unit-PRICE deviation x actual quantity — reflecting purchasing (negotiation, supplier, timing, market). Usage variance measures the QUANTITY deviation (actual vs standard usage) x standard price — reflecting production efficiency (waste, scrap, process). Splitting them lets you target the right department: price issues → purchasing; usage issues → production. This tool covers only price variance; usage needs separate calculation.
How should I set the standard price, and what if it is wrong?
The standard price is the benchmark; its reasonableness determines the variance's value. Set it from recent actual prices, contracted supplier prices, expected market trends/inflation, volume discounts, and freight — usually at annual budgeting and reviewed periodically. If set too low (over-optimistic), almost every period shows unfavourable variance, eroding the warning value; too high (loose) creates fake favourable variances hiding real problems. A reasonable, realistic, periodically updated standard is essential. Persistent one-sided variance is often a signal to revisit the standard.
Does a favourable variance mean the purchasing team did well?
Not necessarily — a key trap. 'Favourable' only means actual price < standard, lowering cost; it does NOT equal 'team performed well'. Reasons to investigate: (1) cheaper but lower-quality substitute material may raise later usage variance, returns or reputation damage — a 'pick up pennies, lose dollars' false saving; (2) market price simply fell, not the buyer's skill; (3) bulk-buy discounts causing overstocking, tying up cash. So see favourable variances alongside usage variance, quality, return rates and inventory — don't auto-reward. Likewise, unfavourable is not automatically blame. Variance analysis guides questions, not verdicts.
How do price and usage variance work together for full analysis?
Total direct-material variance = price variance + usage (quantity) variance; this tool computes only the price half. For full cost control you combine both, pointing to different responsibilities. Price variance (this): 'bought dear or cheap' = (standard price - actual price) x actual quantity, reflecting purchasing (negotiation, supplier, timing, market). Usage variance: 'used sparingly or wastefully' = (standard usage - actual usage) x standard price, reflecting production efficiency (waste, scrap, process, skill). Splitting lets you target the right fix: if overspend is mostly price variance, review sourcing strategy; if mostly usage, improve production/material management. A good standard-cost system tracks both. This tool focuses on price; usage needs the standard vs actual usage data separately.
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參考資料
內容審核：香港計算器財經團隊。計算邏輯與公式參考香港金融管理局（HKMA）及投資者及理財教育委員會（IFEC）之個人理財計算指引，結果僅供參考，實際以相關機構公佈為準。