Formula
- Use the units shown beside each field.
- Results update automatically whenever you change an input.
- Displayed values use up to four decimal places, or scientific notation for very small or large numbers. Calculations use standard floating-point arithmetic; exact integer and fraction tools identify their own precision rules.
- Fat equivalence only. Water, milk solids, flavor and baking behavior also change; this is not a universal recipe substitution.
Example Calculation
- Oil mass to replace: 100 g
- Oil fat content: 100 %
- Butter fat content: 82 %
Replacing 100 g of 100%-fat oil with 82%-fat butter requires about 121.95 g butter to match fat mass.
Frequently asked questions
How do I use this calculator?
Enter oil mass to replace, oil fat content, butter fat content. The result updates automatically. Use Reset to restore the example values.
What method does it use?
butter mass=oil mass × oil fat fraction/butter fat fraction.. Fat equivalence only. Water, milk solids, flavor and baking behavior also change; this is not a universal recipe substitution.
Why might a rounded result differ?
The calculation keeps full numeric precision internally, then rounds the displayed result. Rounding intermediate steps by hand can produce a slightly different answer.
Are my inputs saved online?
No. This calculator processes your inputs in your browser. A recently used list stores only calculator names on this device, not your entered values.
Check the assumptions and units before using this result. Read about calculation methods.