Percent Variance Calculator
Find the variance between two numbers — the absolute change, the percent change from the original value, and the symmetric percent difference — with the formulas and worked examples.
Percent change is measured relative to the original (first) value.
- Absolute change
- 20.00
- Percent difference
- 18.18%
- Original
- 100.00
- New
- 120.00
From 100.00 to 120.00 is a change of 20.00 (20.00%).
How to use this calculator
- Enter the original (starting, budgeted, or reference) value in the first box.
- Enter the new (actual, current, or comparison) value in the second box.
- Read the absolute change, the percent change from the original, and the symmetric percent difference.
What is percent variance between two numbers?
In everyday, business, and finance use, the "variance" between two numbers means how much one value differs from another, usually as a percentage. It answers questions like "how much did sales grow from last month?" or "how far is the actual cost from the budget?" This is different from statistical variance (σ² or s²), which measures the spread of a whole data set — see the note below.
There are three common ways to express the variance between two numbers, and this calculator reports all three:
- Absolute change — simply the new value minus the original.
- Percent change — the change measured against the original value (directional: positive for an increase, negative for a decrease).
- Percent difference — a symmetric comparison against the average of the two values, used when neither number is a natural "starting point".
Percent variance formula
Absolute change (new − original):
Percent change, relative to the original value a:
Percent difference, relative to the average of the two values:
Percent change is undefined when the original value is 0, because there is no baseline to divide by. Use the percent difference instead in that case.Worked example
Suppose last month’s revenue was 100 and this month’s is 120. The variance between the two numbers is:
- Absolute change: 120 − 100 = 20.
- Percent change: 20 ÷ 100 × 100% = 20% (a 20% increase from the original).
- Percent difference: 20 ÷ ((100 + 120) / 2) × 100% = 20 ÷ 110 × 100% ≈ 18.18%.
Percent change (20%) is the figure you report when the original value is a genuine baseline, such as a prior period or a budget. Percent difference (18.18%) is the figure you use when the two numbers are simply two measurements with no natural starting point.
Budget and finance variance
In budgeting, the variance is actual minus budgeted, and the percent variance is that change divided by the budgeted amount. A positive percent variance on revenue is favorable; a positive percent variance on cost is unfavorable.
| Metric | Budget (a) | Actual (b) | Percent variance |
|---|---|---|---|
| Revenue | 10,000 | 11,500 | +15% |
| Materials cost | 4,000 | 4,600 | +15% (over budget) |
Percent variance vs. statistical variance
These are two different ideas that share a name. Percent variance compares two single numbers. Statistical variance measures how spread out a whole set of numbers is around its mean, in squared units.
Looking for statistical variance (σ² or s²) of a data set? Use the Variance Calculator instead. To compare the spread of two data sets relative to their means, use the Coefficient of Variation Calculator.Percent variance in Excel
With the original value in A1 and the new value in B1, the percent change is =(B1-A1)/ABS(A1). Format the cell as a percentage. For the symmetric percent difference use =ABS(A1-B1)/((ABS(A1)+ABS(B1))/2).
Frequently asked questions
How do you calculate variance between two numbers?
Subtract the original number from the new number, divide by the absolute value of the original, and multiply by 100. For example, from 100 to 120 the variance is (120 − 100) / 100 × 100% = 20%.
What is the difference between percent change and percent difference?
Percent change is measured against one value you treat as the original (a baseline such as a prior period), so it is directional. Percent difference is measured against the average of the two values, so it is symmetric and does not depend on which number comes first.
How do I calculate a variance percentage?
Divide the change (new minus original) by the original value and multiply by 100. This gives the percent variance — positive for an increase and negative for a decrease.
Is this the same as statistical variance?
No. This calculator finds the percentage variance between two single numbers. Statistical variance (σ² or s²) measures the spread of an entire data set around its mean — use the Variance Calculator for that.
Why is my percent variance undefined?
Percent change divides by the original value, so it is undefined when the original is 0. Use the absolute change or the percent difference instead when the starting value is zero.