Guide IV · 5 min read
Almost everyone who tracks net worth starts in a spreadsheet. Almost everyone abandons it inside a year. The spreadsheet isn't the problem — the format is. Here's where it quietly falls apart, and what to use instead.
A net worth spreadsheet is a stack of small assumptions: this cell sums that range, this row converts EUR to GBP, this tab pulls the mortgage balance forward each month. It works on day one. Six months in, you've added a crypto wallet, renamed a sheet, dragged a row, and somewhere a formula now points at a blank cell. Your net worth is off by £3,400 and you don't know it.
Spreadsheets fail silently. There's no error message when a SUM stops including the new ISA — the number just looks plausible and is wrong. With money, "plausible and wrong" is the worst possible state. It's the reason most people stop trusting the figure, and once you stop trusting it you stop opening it.
Common spreadsheet failure modes
A spreadsheet was designed for one person on one computer. Google Sheets papers over this, but the underlying problem stays: two people editing the same grid is a recipe for "wait, did you change this?" Permissions are all-or-nothing — either your partner sees every cell including the salary tab, or they see nothing. There's no concept of a shared household with individual privacy on the edges.
And the mobile experience is grim. Updating a balance on your phone while standing in the kitchen means zooming into a 12pt cell, tapping the wrong row, and hoping the formula bar still works. Most couples we talk to have a spreadsheet they "really should update" sitting untouched for four months.
Net worth tracking has three jobs, and a spreadsheet is bad at all three:
The three jobs
Figures is built around those three jobs. You add an account once; every update after that is one number on one screen. Currencies convert on live FX. Two people in the same household see the same figure without one of them owning the file. There are no formulas to break, because there are no formulas — just balances and the maths the app does for you.
We're not anti-spreadsheet. They're brilliant for one-off modelling — "what does the mortgage look like if we overpay £200/month?", "how much will the ISA be worth in 15 years at 6%?" — anything you build once, look at, and close. The failure mode is using them as the ongoing system of record for something that changes every month and is shared with another person.
Model in a spreadsheet. Track in something built for tracking.
Whatever you've got — Google Sheets, Excel, Notion table. Date of the last update? If it's more than two months ago, that's the finding.
Pick three accounts and check the current balance against the bank/broker app. How many match? Spreadsheets quietly drift; you can measure the drift in 5 minutes.
Same balances, takes about 10 minutes. The calculator works without an account if you just want the number; the app saves it and updates monthly.
If you live with someone, this is the step the spreadsheet never managed. Both phones, same figure, no spreadsheet admin.
If you want the underlying logic of household net worth before switching, start with the household net worth guide. Or just get your number — the calculator takes about two minutes and needs no sign-up.