Calculator
Christmas light load calculator
Will this display run on one circuit? Enter your strings and see the watts, the amps and how much of the safe budget you have used.
Both calculators here answer a question the category usually answers with a shrug. Neither hides its formula, and every assumption in both is a field you can change — including the wattage, because the only figure that is really true is the one printed on the tag of the string in your hand.
They are arithmetic, not an inspection. What that means, and where the boundary sits, is on how we research.
Calculator
How many lights calculator
How many strings for a tree of a given height, or for a run of railing at your string's bulb spacing. Prints the arithmetic either way.
Why these two
They are the two questions that decide whether a display works. Everything else in seasonal decorating is preference; these two have right answers, and getting them wrong is how people end up standing in the dark holding a tripped breaker or driving back to a store for two more strings on December 14.
The guides behind them are how many amps do Christmas lights use and how many Christmas lights do I need. Each one carries the full tables, the sources and the reasoning; the calculators are the same arithmetic with your numbers in it.
More coming
A storage size finder — wreath and tree dimensions to container size — and a running cost calculator are next. In the meantime the sizing charts are published in full in wreath storage containers and tree storage bags, and the cost arithmetic is worked through in LED vs incandescent.