Atmospheres to Bar (atm to bar)

Formula

1 atm = 1.01325 bar

bar = atmospheres × 1.01325 — reverse: atmospheres = bar × 0.9869232667

The factor is derived from the SI definitions of both units (base unit: Pa) 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 atm = 5.06625 bar
• 12.5 atm = 12.6656 bar
• 100 atm = 101.325 bar

Atmospheres to bar conversion table

FAQ

How many bar are in one atmosphere?

1 atm = 1.01325 bar. 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 atmospheres to bar?

Multiply the value in atmospheres by 1.01325: bar = atmospheres × 1.01325. For example, 5 atm = 5.06625 bar.

How do I convert bar back to atmospheres?

Multiply by the inverse factor 0.9869232667 (atmospheres = bar × 0.9869232667), or use the bar-to-atmospheres page.

Related conversions

• Bar to atmospheres (reverse)
• Pressure Converter — all pressure units in one tool
• Psi to Bar
• Bar to Psi
• Psi to Kilopascals
• Kilopascals to Psi
• Bar to Kilopascals
• Kilopascals to Bar
• Atmospheres to Pascals
• Pascals to Atmospheres

Machine access

• API: GET https://tttkmbb.com/api/v1/convert?value=5&from_unit=atm&to_unit=bar
• MCP: server https://tttkmbb.com/mcp, tool convert_units with {"value":5,"from_unit":"atm","to_unit":"bar"}
• Markdown: https://tttkmbb.com/conversion/atm-to-bar.md · JSON: https://tttkmbb.com/conversion/atm-to-bar.json (add ?value= for a result) · Units: /api/v1/units?quantity=pressure
• 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)