Convert Attojoules to Kilojoules
Convert Attojoules (aJ) to Kilojoules (kJ) instantly and accurately.
Conversion Formula
kJ = aJ × 1.000000000e-21
About Attojoules
An attojoule (aJ) is 10⁻¹⁸ J - the scale of individual X-ray photons and superconducting qubit circuits. A 1 keV X-ray photon carries 160 aJ; a visible green photon (~550 nm) carries ~0.36 aJ. Josephson junction energies in superconducting qubits are set in tens to hundreds of aJ to achieve quantum coherence at millikelvin temperatures. XRISM's cryogenic TES X-ray spectrometer resolves individual photon energies at the hundreds-of-aJ level with ~7 eV FWHM resolution. 1 aJ = 10⁻¹⁸ J = 6.242 eV.
About Kilojoules
A kilojoule (kJ) is exactly 1,000 J and is the standard energy unit for food and physical chemistry. EU, Australian, and NZ food labels are mandatory in kJ: recommended adult intake is ~8,400 kJ/day. Bond dissociation energies: C-H bond 413 kJ/mol; C=C double bond 614 kJ/mol; N≡N triple bond 945 kJ/mol. Specific heat of water: 4.184 kJ/(kg·K). A cyclist riding at 150 W for one hour expends 540 kJ. Charpy and Izod impact toughness tests record results in J and kJ. 1 kJ = 1,000 J = 239.0 cal = 0.94782 BTU = 0.27778 Wh.
Quick Reference Table
| Attojoules (aJ) | Kilojoules (kJ) |
|---|---|
| 1 aJ | 1 × 10-21 kJ |
| 2 aJ | 2 × 10-21 kJ |
| 5 aJ | 5 × 10-21 kJ |
| 10 aJ | 1 × 10-20 kJ |
| 25 aJ | 2.5 × 10-20 kJ |
| 50 aJ | 5 × 10-20 kJ |
| 100 aJ | 1 × 10-19 kJ |