Complete Collection — every workbook for $99|Pay with BLIK · Przelewy24 · card · Apple Pay · Google Pay
Home › Blog
Blog

The maths behind the ritual.

Worked guides on one number at a time — break-even ROAS, landed cost, safe discounts, paycheck budgets, the 52-week challenge — written the way the workbooks think: a formula, an example, a verdict.

28guides
~4min each
Sort:
Money · 3 min read · 5 Oct 2026 Latest

How to set up a family budget spreadsheet you will still open in March

Most family budget spreadsheets die by February. Set one up around a single number, a ten-minute weekly check and categories that match real life — step by step.

Ends in Household Money Ritual — the workbook that does this maths
5 Oct 2026Read →
Money · 3 min read

How to budget as a couple: one shared number instead of monthly arguments

Joint, separate or hybrid accounts? How to split bills fairly, agree on a no-questions allowance and run a ten-minute weekly money check together.

5 Oct 2026Read →
Sellers · 4 min read

Black Friday for small online shops: 6 numbers to know before the sale

Before Black Friday, know six numbers: profit per order, max discount, break-even ROAS at the discount, cash in stock, lowest cash to January and your real payout rate.

25 Sep 2026Read →
Sellers · 3 min read

How much stock to buy before Black Friday (without trapping your cash)

A worked method for Black Friday stock: coverage until the next delivery, a peak-week multiplier, safety stock — and which slow sellers to clear instead of reorder.

25 Sep 2026Read →
Money · 3 min read

How to plan a holiday budget that survives January

A holiday budget that holds: list people × amounts, add the five categories everyone forgets, save it weekly from October, and track what is left as you buy.

25 Sep 2026Read →
Money · 3 min read

Paying off Christmas: a 90-day plan for holiday credit card debt

$1,800 of holiday spending on a card at 24% APR: 11 years and $2,487 of interest on minimum payments, or 3 months and $72. How to set the payment and find it.

25 Sep 2026Read →
Business · 3 min read

How to raise prices without losing profit: the break-even customer loss

A 10% price rise on a 40% margin can lose 20% of customers and still earn the same. The break-even formula, a worked example, and how to roll it out in January.

25 Sep 2026Read →
Money · 3 min read

The January money reset: 5 numbers to write down before the year starts

Skip the resolutions. Write down five numbers in January — net worth, monthly essentials, months of safety, debt-free date and savings rate — and check them once a month.

25 Sep 2026Read →
Sellers · 4 min read

The Shopify profit margin calculator every store owner should run before Black Friday

Your Shopify dashboard shows revenue, not profit. Learn to calculate real per-order profit margin from COGS, shipping, fees and ads, with a worked $45 order.

23 Sep 2026Read →
Business · 4 min read

Cash runway: how many months you actually have, and why 13 weeks beats 12

Learn to calculate cash runway correctly with net burn, why a 13-week forecast beats a 12-month one, and a worked example starting from $38,000.

23 Sep 2026Read →
Sellers · 4 min read

Etsy fees: what a $30 sale actually leaves you, line by line

Break down every Etsy fee on a $30 sale — listing, transaction, payment processing, Offsite Ads, currency conversion — and learn to price so they're covered.

23 Sep 2026Read →
Business · 4 min read

Your freelance hourly rate isn't what you quoted: the effective rate method

Calculate your real freelance hourly rate from ALL hours worked, not just billable ones, with a worked $80/h quoted to $41/h effective example.

23 Sep 2026Read →
Money · 5 min read

Sinking funds explained: how to stop 'surprise' expenses that aren't actually surprises

Learn what a sinking fund is, the formula (amount ÷ months left), and how a household setting aside $310/month ends surprise expense months for good.

23 Sep 2026Read →
Sellers · 5 min read

Amazon FBA profit per unit: the real number after fees, storage, and ads

Revenue is not profit. Calculate true Amazon FBA profit per unit after referral fees, fulfillment fees, storage, and PPC, with a worked example.

23 Sep 2026Read →
Sellers · 5 min read

Inventory turnover ratio for small shops: how to find the cash trapped on your shelves

Learn to calculate inventory turnover ratio and days of stock per SKU, spot slow movers with the 90-day test, and set a reorder point that works.

23 Sep 2026Read →
Money · 5 min read

How much emergency fund do you actually need? A formula, not a rule of thumb

Calculate the right emergency fund size from your essential monthly costs, not total spending, with a worked household example and a starter goal.

23 Sep 2026Read →
Business · 5 min read

LTV to CAC ratio for small businesses: how to calculate it without fooling yourself

Calculate CAC and LTV from real cohort data, understand the 3:1 rule's limits, and compute CAC payback months with a worked small-business example.

23 Sep 2026Read →
Business · 5 min read

Rental property cash flow: the calculation that matters more than the purchase price

Calculate rental property net cash flow, cap rate, and cash-on-cash return with a worked $240,000 example, plus the 1% rule used correctly.

23 Sep 2026Read →
Sellers · 3 min read

Break-even ROAS: the one number every product needs before you spend a dollar on ads

ROAS is not profit. Learn how to calculate break-even ROAS and target ROAS per product from price, COGS, shipping and fees — with a worked example and a free formula.

22 Sep 2026Read →
Money · 3 min read

Debt snowball vs avalanche: which one gets you a date — and how to pick in five minutes

Snowball pays smallest balance first, avalanche pays highest rate first. Here is what each one costs in interest and months, and a simple rule for choosing.

19 Sep 2026Read →
Money · 3 min read

Budgeting by paycheck: why monthly budgets fail when you are paid every two weeks

Paid biweekly? A monthly budget breaks in the third week. Here is the paycheck budget method: assign every bill to the check that covers it and keep one safe-to-spend number.

16 Sep 2026Read →
Money · 3 min read

The 52-week savings challenge, fixed: reverse it, scale it, and stop quitting in March

The classic 52-week challenge saves $1,378. Here is why most people quit by spring, the reverse version that fixes it, and how to scale it to any goal.

13 Sep 2026Read →
Sellers · 3 min read

How to calculate landed cost per unit (and why your margin is smaller than your invoice says)

Landed cost = unit price + freight, insurance, duty, customs and fees, converted at the rate you paid. Step-by-step method with allocation by value, weight or units.

10 Sep 2026Read →
Sellers · 3 min read

How much can you discount before you lose money? The break-even uplift, explained

A 20% discount often needs 40–80% more units just to break even. Learn the max safe discount and break-even uplift formulas before Black Friday.

7 Sep 2026Read →
Sellers · 3 min read

The reseller death pile: how unlisted inventory quietly kills a flipping business

Bought but not listed is the most expensive stock a reseller owns. How to measure the death pile, sell-through and real profit per item on eBay, Poshmark and Depop.

4 Sep 2026Read →
Money · 3 min read

How much house can you actually afford? The 28/36 rule, the cash at closing and the number lenders skip

Lenders tell you what they will lend. This is how to work out what you can carry: the 28/36 rule, real monthly housing cost with taxes, insurance and PMI, and the cash you need at closing.

1 Sep 2026Read →
Business · 3 min read

Vending machine profit per machine: the four costs that turn $400 of sales into $90

How to calculate net profit per vending machine: sales minus restock, location commission, card fees and the real cost of every service visit — plus payback and when to pull a machine.

29 Aug 2026Read →
Money · 3 min read

A grocery budget for a family of four that actually holds: the three numbers, and the takeaway leak

Set a weekly grocery budget for a family of four, catch the eating-out creep that hides a third of food spend, and cut food waste with three numbers checked every Sunday.

26 Aug 2026Read →
Nothing matches — try another word or topic.
Free · Lite edition
Read one, then try one.

The Household Money Ritual, Lite: same formulas and verdicts, tables capped at 30 rows. E-mail in, file out — plus a note when a new guide ships.

Household Money Ritual — dark edition