Practical guides
Start with the problem.
Then test the numbers.
Work through a decision, see an example, and change the assumption that matters. Choose a money, work, or project question below.
How do I compare outcomes when assumptions change?
Keep a baseline visible, change one uncertain input, and compare the consequence before deciding what to do.
Read guide Clear reasoningHow do I decide when numbers are only part of the answer?
Separate measurable facts, uncertain assumptions, and qualitative tradeoffs before comparing options.
Read guide Practical decision guideHow much emergency fund do I need?
How much cash would remain after a surprise bill, and how many essential months would it cover? Work through both questions with editable assumptions.
Read guide Practical decision guideHow long will my savings last?
If income stops or falls, estimate how long savings cover essential spending and how changing costs alter the timeline.
Read guide Practical money guideCoast FIRE vs FIRE: two different milestones
Compare Coast FIRE with full financial independence using transparent retirement targets, compounding assumptions, and editable examples.
Read guide Work decision guideIs a higher salary worth a longer commute?
Compare the pay and time demanded by a job offer, then keep benefits, flexibility, and career growth visible as separate judgments.
Read guide Independent work guideHow much should I charge as a contractor?
Work backward from desired income, business costs, a tax assumption, and realistic billable hours to find a planning rate.
Read guide Housing decision guideCan I afford a mortgage if costs rise?
Test how a higher mortgage rate or recurring property costs would change the monthly housing load before making a decision.
Read guide Small business guideHow long can my business run if revenue falls?
Estimate business cash runway when recurring revenue drops, expenses change, or incoming cash arrives later than planned.
Read guide Project planningHow do I estimate a project when costs change?
Build a small project estimate from tasks, hours, contingency, and a rate. Change one assumption and see the effect without rebuilding a spreadsheet.
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