BTC spot Loading... via Coinbase
Independent calculator · Market data: Coinbase

Methodology

Calculator Methodology

The math room behind the money room: formulas, assumptions, limitations, and how to read calculator output without fooling yourself.

WealthClock calculators are transparent scenario models. The arithmetic is deterministic; the future inputs are not. This page documents the formulas, timing conventions, data source, rounding, exclusions, and checks used across the site.

Methodology principles

Bitcoin calculators

Future value

Future gross value = BTC owned × assumed future BTC price

The Bitcoin Future Value Calculator does not model a probability, date, tax consequence, transaction fee, spread, custody cost, or selling strategy. The output is a direct multiplication of two user-controlled values.

Bitcoin required for a wealth target

BTC required = target dollar amount ÷ assumed future BTC price

For example, a $1,000,000 target divided by a $250,000 BTC assumption equals 4 BTC. This is a gross target before costs or taxes. It does not say that Bitcoin will reach $250,000 or that holding 4 BTC is appropriate for anyone.

Live spot price

Where a current BTC price is displayed, WealthClock requests the Coinbase BTC-USD spot endpoint. The timestamp is shown on the page. If the request fails, the calculators remain usable with manual inputs. A live price is market context, not a recommendation.

Compound-growth calculators

Starting balance

FV of starting balance = P × (1 + r)n

P is the starting principal, r is the periodic rate, and n is the number of periods.

Recurring contributions

FV of end-of-period contributions = PMT × [((1 + r)n − 1) ÷ r]

WealthClock models monthly contributions at the end of each month unless a page explicitly states otherwise. The annual return is divided by 12 to create a monthly rate. When the rate is zero, the formula becomes starting balance plus contributions.

Monthly amount needed for a goal

Required PMT = (target − future value of current balance) × r ÷ ((1 + r)n − 1)

If the current balance alone is projected to exceed the target under the chosen assumptions, the required monthly contribution is shown as zero.

Fee-drag calculations

The Hidden Fees Analyzer compares a no-fee scenario with a net-return scenario. Its simplified model subtracts the annual fee percentage from the assumed gross return and compounds both paths over the same timeline.

Modeled net return = assumed gross return − annual fee

This does not capture every trading cost, tax effect, turnover cost, spread, account fee, or performance difference. It isolates one question: how much can a recurring percentage drag change a long-term modeled result?

Shared conventions and exclusions

ItemWealthClock convention
CurrencyU.S. dollars unless otherwise labeled
Contribution timingEnd of month for recurring-growth tools
Display roundingUsually nearest dollar; underlying calculations retain more precision
Negative returnsAccepted where the calculator supports them, subject to input limits
InflationExcluded unless explicitly modeled
TaxesExcluded
FeesExcluded except in the Hidden Fees Analyzer or where explicitly entered
GuaranteesNone; all future values are scenarios

Quality checks and corrections

  1. Default examples are recalculated independently before publication.
  2. Formula descriptions are compared with the implemented JavaScript.
  3. Calculator inputs are tested at zero, low, default, and high values.
  4. Internal links, canonical URLs, sitemap entries, and mobile layouts are checked before deployment.
  5. Visible source and update information is reviewed when content changes.

Errors can be reported through the contact page. Material corrections are applied to the page and its updated date. WealthClock may improve wording or layout without changing the mathematical method.

Plain-language promise

The formula is the stable part. The assumption is the fragile part. WealthClock will keep those two things visibly separate.

Independent comparison tools