Attoseconds to Femtoseconds Converter

An electron orbits a hydrogen atom in approximately 150 attoseconds. A chemical bond vibrates in femtoseconds. These are the shortest time scales directly accessible to experimental measurement, and the calculator for attoseconds to femtoseconds converts instantly between these two ultrashort time units that define the frontier of ultrafast physics and chemistry.

The Exact Conversion

The relationship between attoseconds and femtoseconds is straightforward:

1 femtosecond (fs) = 10⁻¹⁵ seconds = 1,000 attoseconds

1 attosecond (as) = 10⁻¹⁸ seconds = 0.001 femtoseconds

Both sit within the broader ultrashort time hierarchy:

• 1 millisecond (ms) = 10⁻³ s
• 1 microsecond (μs) = 10⁻⁶ s
• 1 nanosecond (ns) = 10⁻⁹ s
• 1 picosecond (ps) = 10⁻¹² s
• 1 femtosecond (fs) = 10⁻¹⁵ s
• 1 attosecond (as) = 10⁻¹⁸ s

Use this online calculator for any time unit conversion at ultrashort scales. The femtoseconds to picoseconds converter handles the next scale up in the time hierarchy.

What Happens at Femtosecond and Attosecond Timescales

These timescales correspond to fundamentally different physical processes:

• Attosecond scale (10⁻¹⁸ s): electron dynamics — orbital motion, photoionization, Auger processes; the 2023 Nobel Prize in Physics awarded for attosecond pulse generation enabling direct observation of electron motion in atoms and molecules
• Femtosecond scale (10⁻¹⁵ s): nuclear motion — chemical bond vibrations (C–H stretch: ~9 fs), proton transfer reactions, photodissociation; the 1999 Nobel Prize in Chemistry (Ahmed Zewail, "femtochemistry") awarded for observing chemical reactions in real time using femtosecond laser pulses

The distinction between attosecond and femtosecond science is not merely quantitative — electrons are 1,836× lighter than the lightest nucleus (hydrogen), so electronic motion is approximately 1,836× faster than nuclear motion. Attosecond pulses probe electrons; femtosecond pulses probe nuclei and chemical bonds.

Attosecond Pulse Generation: Nobel Prize Technology

Attosecond light pulses are generated through high-harmonic generation (HHG) — a highly nonlinear optical process where an intense femtosecond infrared laser pulse drives electrons in a gas to tunnel-ionize, accelerate, and recombine with their parent ion, emitting extreme ultraviolet radiation in attosecond bursts. The shortest attosecond pulses produced to date are approximately 43 attoseconds (as of the early 2020s). These pulses are used to "take movies" of electron motion in atoms and molecules — a capability previously thought impossible. Pierre Agostini, Ferenc Krausz, and Anne L'Huillier won the 2023 Nobel Prize in Physics for developing this technology. The picoseconds to nanoseconds converter and time converters cover the full ultrashort time scale toolkit.

Light Travel Distance at Ultrashort Timescales

Light travels at 2.998 × 10⁸ m/s in vacuum. The distance light travels in ultrashort intervals:

• In 1 femtosecond: 299.8 nm ≈ 0.3 μm (about the wavelength of UV light)
• In 1 attosecond: 0.2998 nm ≈ 0.3 nm (about the diameter of a small atom)

This means attosecond pulses of light are spatially as thin as atomic dimensions — which is why they can probe atomic-scale electron dynamics without spatial smearing.