Fuse Size Calculator
DC fuse rating from device wattage and cable run.
About the Fuse size calculator
Use this fuse size calculator for van leisure battery & solar setup. DC fuse rating from device wattage and cable run.
Enter your fuse size details
Or use the inverter's continuous rating.
25% is standard. Inverters often need 30–50%.
Where to fit it
Always fuse on the positive line, as close to the battery as possible (within 18 cm / 7"). The fuse protects the cable, not the device.
Your fuse size results
Operating current
50 A
@ 12 V
Calculated rating
62.5 A
+25% margin
Use a fuse of
80 A
Next standard size up
Why fuse size matters for van leisure battery & solar setup
Plan with confidence
Getting your fuse size numbers right early avoids costly rework, undersized components and surprises on the road.
Related battery & solar tools
Pair this with the rest of our battery & solar calculators to plan your full van conversion.
Fuse size calculator FAQ
- What does the Fuse Size Calculator do?
- DC fuse rating from device wattage and cable run. It is designed for van leisure battery and solar so you can plan with confidence.
- Is the fuse size calculator free to use?
- Yes. All VanTools calculators, including the Fuse Size Calculator, are free to use with no sign-up required.
- How accurate are the fuse size results?
- Results are estimates based on the values you enter and standard van leisure battery and solar assumptions. Always sanity-check against manufacturer data and your real-world conditions.
- Can I share or save my fuse size calculation?
- Yes. Use the Share button to copy a link that includes your inputs, or use Export to download a PDF or image of your results.