Sum running watts (or enter appliance fields), divide by shore voltage, and compare to 30A / 50A pedestals with an 80% continuous budget.
This tool helps when you want a shore power amp estimate with the assumptions written down. Enter shore voltage (V), total running watts (optional override), appliance 1 (W), and appliance 2 (W).
Sum running watts (or enter appliance fields), divide by shore voltage, and compare to 30A / 50A pedestals with an 80% continuous budget.
Amps equal total watts divided by voltage. The page flags load against 30A and 50A pedestals and shows the common 80% continuous budget (24A on 30A; 40A on 50A).
amps = total_watts ÷ voltage
budget_30 = 30 × 0.8 = 24 A | budget_50 = 50 × 0.8 = 40 A
Does not model power-factor, surge, or ELCI trips. Use nameplate watts or a Kill-A-Watt style meter.
Example inputs from the form defaults — Shore voltage (V) = 120; Appliance 1 (W) = 1500; Appliance 2 (W) = 600; Appliance 3 (W) = 400 — are chosen to be plausible coastal/cruising figures, not your boat’s survey.
Compute with: amps = total_watts ÷ voltage budget_30 = 30 × 0.8 = 24 A | budget_50 = 50 × 0.8 = 40 A.
When the calculator and your scratch math disagree, fix units first; the shore power amp model is only as good as consistent inputs.
Assumptions: inputs for this shore power amp estimate match the hints (soundings, nameplate Ah, marked tank capacity, and so on).
Many shore-power practices derate continuous load to about 80% of breaker rating. Confirm with your panel labels and marina rules.
Enter the voltage your loads actually see. A 50A 240V pedestal is not the same as 50A at 120V — check your inlet wiring.
Motors and A/C compressors draw more at start. Size with headroom beyond steady watts.