FRET Efficiency Calculator
Calculate Forster Resonance Energy Transfer efficiency and estimate molecular distances
Calculation Method
Distance at 50% FRET efficiency
Common FRET Pairs (R₀)
FRET Efficiency
33.3%
E = 0.3333
Estimated Distance
6.06 nm
R₀ = 5.4 nm
FRET Distance Relationship
0.5 R₀R₀ (50%)2 R₀
Interpretation
Distance is greater than R₀ - moderate FRET
About FRET
Forster Resonance Energy Transfer (FRET) is a distance-dependent energy transfer between a donor and acceptor fluorophore.
E = R₀⁶ / (R₀⁶ + r⁶)
- R₀ (Forster radius): Distance at which FRET efficiency is 50%
- Sensitive range: 0.5 R₀ to 2 R₀ (typically 1-10 nm)
- Applications: Protein-protein interactions, conformational changes, molecular rulers