Convert Joules to Megajoules (J to MJ)
1 joule (J) equals 0.000001 megajoules (MJ).
1 J = 0.000001 MJ
Type in either box. Scientific notation works: 1.5e-3.
Converting a list? Use the bulk joule to megajoule converter to paste a column from Excel.
How to Convert Joule to Megajoule
- 1 J = 0.000001 MJ
- 1 MJ = 1000000 J
- Example: convert 15 J to MJ: 15 J = 15 × 0.000001 MJ = 0.000015 MJ
Formula
MJ = J ÷ 1000000
Derivation from SI units:
- 1 J = 1 N·m = 1 W·s = 1 kg·m²·s⁻²
- 1 MJ = 10⁶ J
Both units are defined exactly, so the factor is exact. Joule definition: joule; Megajoule definition: megajoule.
Worked examples
- A reading of 250 J converts to 0.00025 MJ.
250 J × 0.000001 = 0.00025 MJ - A value of 10000 J is 0.01 MJ.
10000 J × 0.000001 = 0.01 MJ
Joule to Megajoule conversion table
| Joules (J) | Megajoules (MJ) |
|---|---|
| 1 J | 0.000001 MJ |
| 10 J | 0.00001 MJ |
| 100 J | 0.0001 MJ |
| 250 J | 0.00025 MJ |
| 500 J | 0.0005 MJ |
| 1000 J | 0.001 MJ |
| 4184 J | 0.004184 MJ |
| 10000 J | 0.01 MJ |
| 100000 J | 0.1 MJ |
| 1000000 J | 1 MJ |
| 3600000 J | 3.6 MJ |
Where it's used
Joules are used for physics and engineering energy balances, while megajoules appear in fuel heating values (natural gas ≈ 38 MJ/m³, diesel ≈ 45 MJ/kg). Both measure energy, work and heat, so the conversion is a fixed factor.
Joule to other energy units
| Conversion | 1 J equals |
|---|---|
| joule to kilojoule | 0.001 kJ |
| joule to megajoule | 0.000001 MJ |
| joule to calorie | 0.2390057361 cal |
| joule to kilocalorie | 0.0002390057361 kcal |
| joule to watt-hour | 0.0002777777778 Wh |
| joule to kilowatt-hour | 2.777777778 × 10⁻⁷ kWh |
| joule to BTU | 0.0009478171203 BTU |
| joule to therm | 9.48043428 × 10⁻⁹ thm |
| joule to electronvolt | 6.241509074 × 10¹⁸ eV |
| joule to foot-pound | 0.7375621493 ft·lbf |
| joule to erg | 10000000 erg |
Frequently asked questions
How many megajoules are in 1 joule?
1 J = 0.000001 MJ.
How do I convert joules to megajoules?
Multiply the value in J by 0.000001, or divide it by 1000000. For example, 15 J × 0.000001 = 0.000015 MJ.
Is the J to MJ conversion exact?
Yes. Both units are defined exactly, and 1 J is exactly 0.000001 MJ.
Sources
- The International System of Units (SI), 9th edition (SI Brochure), Bureau International des Poids et Mesures , Table 4, coherent derived units with special names.
- The International System of Units (SI), 9th edition (SI Brochure), Bureau International des Poids et Mesures , Table 7, SI prefixes.
Last reviewed: . Factors are stored exactly and computed with 50-digit decimal arithmetic. See how we verify conversion factors.
Cite this page
APA
Scientific Converters. (2026, October 15). Convert Joules to Megajoules (J to MJ). Retrieved October 18, 2026, from https://scientificconverters.com/energy/joules-to-megajoules/
IEEE
Scientific Converters, "Convert Joules to Megajoules (J to MJ)," scientificconverters.com. Accessed: Oct. 18, 2026. [Online]. Available: https://scientificconverters.com/energy/joules-to-megajoules/