Fluorescence Lifetime Calculator

Calculator Inputs

Calculation method

Pick the measurement type you have.

Output unit for lifetime

All methods will convert to this unit.

Significant figures

Controls rounding in the result table.

Rates input

Radiative rate k_r

Non-radiative rate k_nr

Rate unit

Lifetime is computed by τ = 1/(k_r + k_nr).

Example Data Table

Scenario	Inputs	Output (τ)
Rates method	k_r=2.5 1/ns, k_nr=0.5 1/ns	0.333 ns
Quantum yield method	Φ=0.83, τ_r=4.2 ns	3.486 ns
Two-point decay	t₁=0 ns, I₁=1000; t₂=3 ns, I₂=368	3.000 ns
Multi-exponential	a=[0.7,0.3], τ=[1.2,4.8] ns (intensity-weighted)	3.129 ns

These examples are illustrative and depend on rounding.

Formula Used

Fluorescence lifetime τ describes how quickly emission decays after excitation. Common models assume first‑order decay and convert your measurements into a characteristic time constant.

Rates: τ = 1/(k_r + k_nr), where k_r is radiative and k_nr is non‑radiative decay rate.
Quantum yield: Φ = k_r/(k_r + k_nr) and τ_r = 1/k_r, giving τ = Φ·τ_r.
Two‑point decay: with I(t)=I₀e^-t/τ, then τ=(t₂-t₁)/ln(I₁/I₂).
Multi‑exponential average: choose amplitude‑weighted τ̄=Σ(a_iτ_i)/Σ(a_i) or intensity‑weighted τ̄=Σ(a_iτ_i²)/Σ(a_iτ_i).

How to Use This Calculator

Select a calculation method that matches your data.
Enter values with the correct units (rates or times).
Choose an output unit and significant figures.
Click Compute lifetime to view the results above.
Use the CSV/PDF buttons to export the result summary.

Fluorescence Lifetime Calculator

Calculator Inputs

Rates input

Quantum yield input

Two-point decay input

Multi-exponential components

Example Data Table

Formula Used

How to Use This Calculator

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