Percentage Difference Calculator
The symmetric version of % change — useful when neither value is «before» the other. Defaults to 120 vs 100 = 18.18% difference.
Use this for comparing two quotes, two test results, or any two values where neither is the baseline. The maths divides the absolute difference by the average.
How it works.
Formula: |A − B| ÷ ((A + B) ÷ 2) × 100.
How to calculate percentage difference between two numbers, step by step:
- Take the absolute difference between the two numbers: |A − B|.
- Average the two numbers: (A + B) ÷ 2.
- Divide step 1 by step 2.
- Multiply by 100 to get the percentage.
Worked example — between 180 and 65: |180 − 65| = 115; (180 + 65) ÷ 2 = 122.5; 115 ÷ 122.5 = 0.939; × 100 = 93.88% difference. The result is symmetric — swapping A and B gives the same answer.
Worked examples
£500 vs £600 quotes = 18.18% difference — comparing two car insurance renewals, neither of which is «the original».
£80,000 vs £85,000 = 6.06% difference — comparing salaries in a job offer.
£250k vs £275k house valuations = 9.52% difference — useful for valuation reconciliation.
Frequently asked questions
How do you calculate the percentage difference between two numbers?
Take the absolute difference, divide by the average of the two numbers, multiply by 100. For 180 and 65: |180 − 65| = 115; (180 + 65) ÷ 2 = 122.5; 115 ÷ 122.5 × 100 = 93.88%.
What is the percentage difference between 180 and 65?
About 93.88%. Calculation: |180 − 65| ÷ ((180 + 65) ÷ 2) × 100 = 115 ÷ 122.5 × 100.
How is this different from percentage change?
Percentage change uses one value as the baseline (Original). Percentage difference uses the average of both as the baseline, so the result is the same regardless of order.
What is the percentage variance formula?
«Percentage variance» in everyday UK use is the same as percentage difference: |A − B| ÷ ((A + B) ÷ 2) × 100. In statistics, «variance» means something different (Var = E[(X − μ)²]); use the standard-deviation calculator for that.
When should I use difference vs change?
Change for time series (before/after). Difference for symmetric comparisons (quote A vs quote B).