FREE TOOLS
Before & after measurement log
Record repeat measurements and compare like-for-like readings.
YOUR OBSERVATIONS
Compare the same conditions.
Use the same instrument, mode, location, orientation and units for each pair.
No measurements yet. Add your first matched pair.
How changes are calculated
Percentage change = (after − before) ÷ before × 100. A positive number means an increase; a negative number means a decrease. When the baseline is zero, percentage change is undefined. Readings below an instrument’s detection floor should not be entered as measured zero.