Spreadsheet template guides

Step-by-step guides with worked examples. Every number in an example is computed by a script, and each guide links its sources.

• How to size a cable to IEC 60364: a worked example with derating and voltage drop

  Work out the design current Ib and choose the next standard breaker In. Divide In by the product of the ambient, grouping and soil correction factors to get the rating the cable needs. Pick the smallest size with that rating, check the voltage drop, keep the larger of the two sizes, and confirm Ib ≤ In ≤ Iz.

  Updated 2026-10-26

• How to build a construction schedule in Excel (with a 12-week example)

  A construction schedule in Excel needs one row per task with its phase, trade, duration in working days and the task that must finish first. Start dates are then calculated from those links, and inspections and permits are listed as their own rows or flags. The longest chain of linked tasks, the critical path, sets the finish date.

  Updated 2026-10-26

• Debt snowball vs debt avalanche: which pays off faster?

  The debt avalanche (highest APR first) always costs the same or less interest than the debt snowball (smallest balance first), and it is often no slower. The snowball clears your first debt sooner, which research links to staying motivated. If you will stick with either plan, avalanche saves money; if motivation is the risk, snowball can be the better bet.

  Updated 2026-10-26

• How to make a Gantt chart in Google Sheets (2 methods)

  Google Sheets has no Gantt chart type, so you build one. Either make a stacked bar chart from a start-offset column and a duration column and hide the first series, or lay out a row of dates and colour each task's cells with a conditional formatting custom formula such as =AND(D$1>=$B2, D$1<=$C2).

  Updated 2026-10-26

• How to size an off-grid solar system: panels, battery and inverter

  Add up each appliance's daily watt-hours and divide by inverter efficiency. Divide that by worst-month peak sun hours times a loss factor (0.780 in our example), plus a 10% margin, to get array watts. Battery capacity is daily energy times days of autonomy divided by depth of discharge. Then check cold-weather string Voc and inverter surge.

  Updated 2026-10-26