DCC Power Budget Calculator
Description
Every locomotive, lit passenger car, and powered accessory on your layout draws current from your DCC booster at the same time trains are running. Add each one's current draw — from its own manufacturer spec sheet, or a current you've measured yourself — and this calculator totals them up and checks that total against your booster's rated output, so you know whether you need a second booster (and a power district split) before you're surprised by one on the layout.
The safety margin lets you hold back some of your booster's rated capacity rather than planning to run it right at the nameplate number. That's a buffer you choose, not a fixed rule — but it's a reasonable one, because a booster's actual sustained output depends on real conditions (supply voltage, room temperature, heat-sink airflow) that can leave it short of its rated number in practice, not just on the number printed on the box.
Sources
A DCC booster's "rated output current" is a manufacturer-published spec, not a figure the NMRA's DCC electrical standards (S-9.1 and its related documents) define or standardize — each DCC company sets its own rating by its own internal test method. Digitrax's own technical note on booster output ratings confirms this directly, and explains that the current a booster can actually sustain also depends on input voltage, ambient temperature, and heat-sink airflow, not just the nameplate value — which is why this calculator treats the margin as something you decide, not a number it asserts.
Disclaimer: enter your booster's own published rating and your own locomotives' and accessories' own published current draws — this calculator doesn't assume or supply any product's specs. If a spec can't be sourced from the manufacturer, measure it yourself before relying on it.