Watt-hours to Joules (Wh to J)

Formula

1 Wh = 3600 J

joules = watt-hours × 3600 — reverse: watt-hours = joules × 0.0002777777778

The factor is derived from the SI definitions of both units (base unit: J) as listed in NIST SP 811; results on this page are shown to 6 significant figures, the API returns up to 12.

Worked examples

• 5 Wh = 18000 J
• 12.5 Wh = 45000 J
• 100 Wh = 360000 J

Watt-hours to joules conversion table

FAQ

How many joules are in one watt-hour?

1 Wh = 3600 J. The factor comes from the SI definitions of both units (NIST SP 811 / BIPM), so it is exact or correct to at least 10 significant figures.

What is the formula to convert watt-hours to joules?

Multiply the value in watt-hours by 3600: joules = watt-hours × 3600. For example, 5 Wh = 18000 J.

How do I convert joules back to watt-hours?

Multiply by the inverse factor 0.0002777777778 (watt-hours = joules × 0.0002777777778), or use the joules-to-watt-hours page.

Related conversions

• Joules to watt-hours (reverse)
• Energy Converter — all energy units in one tool
• Kilocalories (food calories) to Kilojoules
• Kilojoules to Kilocalories (food calories)
• Joules to Calories (small, thermochemical)
• Calories (small, thermochemical) to Joules
• Kilowatt-hours to Megajoules
• Megajoules to Kilowatt-hours
• Kilowatt-hours to BTU
• BTU to Kilowatt-hours

Machine access

• API: GET https://tttkmbb.com/api/v1/convert?value=5&from_unit=Wh&to_unit=J
• MCP: server https://tttkmbb.com/mcp, tool convert_units with {"value":5,"from_unit":"Wh","to_unit":"J"}
• Markdown: https://tttkmbb.com/conversion/wh-to-joules.md · JSON: https://tttkmbb.com/conversion/wh-to-joules.json (add ?value= for a result) · Units: /api/v1/units?quantity=energy
• OpenAPI operationId: convert_units. Freshness: static. Authentication: none.

Sources

• NIST Special Publication 811 – Guide for the Use of the International System of Units (SI), Appendix B conversion factors (standard)
• BIPM – The International System of Units (SI Brochure, 9th edition) (standard)
• Wikipedia – Conversion of units (reference)