The CEO of a small firm once told me, “With what I can afford to pay, it’s impossible to keep good help. The help I do get needs a lot of training—and even then…” So what do you do? The answer is simple: you build bulletproof spreadsheets that help the user get it right every time.
A good example is Ray’s Fly Shop. Ray once owned a brick-and-mortar fly shop but eventually closed it in favor of the online business he had built while running the store. www.RaysFlies.com has been his bread and butter for the past ten years.
“Rent, utilities, insurance, and staffing the store were chewing up too much of my profits,” Ray explains. “And I had the space in my basement for the inventory.”
Now that Ray’s is a global supplier, his only additional expenses are regular advertisements in Fly Tyer, Fly Fisherman, Fly Rod & Reel, and American Angler magazines. Ray attributes he success to the quality of his flies. He carefully selects suppliers who tie each fly he carries that meet his exacting standards.
Well-controlled spreadsheets are a business owner’s best friend.
He employs a neighbor with kids in school who comes over and helps with stocking, fulfillment, and inventory. He’s had several helpers over the last ten years and has learned that well-controlled spreadsheets are a business owner’s best friend.
Over the years he learned that if the system is designed correctly, even a brand-new helper can do the job accurately. Each spreadsheet guides the user step by step—whether stocking flies, recording rod and reel purchases, tracking fly lines, or managing other equipment inventory. Built-in checks validate entries, prevent common mistakes, and automate repetitive tasks.
With a little help from VBA and, more recently, AI-assisted code, Ray created a system that keeps ordering, inventory tracking, and supplier selection running smoothly. While Ray runs a fly-fishing business, the design principles behind his spreadsheets apply to almost any business. When spreadsheets are carefully structured and automated, they become reliable systems that help people do the right thing every time.
In the following sections, we’ll look at how a “bulletproof” spreadsheet like Ray’s can be designed.
Ray’s Ten Commandments of Building a Bulletproof Spreadsheet
- Document the workbook/spreadsheet thoroughly. --Guide the user with clear instructions
- Protect the structure of the spreadsheet.
- Validate every user input (where possible).
- Never trust manual calculations.
- Avoid a key person dependency
- Use dropdown lists whenever possible.
- Separate data, logic, and presentation.
- Automate repetitive tasks with VBA.
- Force automated Backup to an alternative location (preferably offsite).
- Design every sheet so a new employee can use it.
Document the workbook/spreadsheet thoroughly
When I started my career as an auditor, I was told to build spreadsheets that could answer every question a user might have—so anyone could open the workbook and immediately understand it. This is a tedious process so have AI do as much of it as possible. Over the years, I’ve seen hundreds of workbooks, ranging from the sublime to the downright terrible.- Remember a successful workbook has consistency, clarity, and structure.
- Avoid the excessive use of color , shading etc-- Keep it simple and business like.
- keep the headings precise
- The goal is to have a new user be able to quickly understand it
- if there is VBA code be sure it is fully annotated If there are complex nested formulas consider:
- 1. Break the Formula into Logical Steps
Instead of one huge nested formula, split it into helper columns or cells. - 2. Use Named Ranges
Replace cryptic references like C1:C10 with names. - 3. Use Cell Comments / Notes
Add comments to the cells with complicated formulas. - 4. Create a “Documentation” Worksheet
For extremely complex sheets, add a sheet called "Documentation or Logic Notes." For example a new derivative product pricing model full of complex math will likely be born in a spreadsheet