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Before and after
Two complete examples
See what stays factual, what remains unknown, and what becomes easier to do next.
Materials, waste, labor, and tax
Static sample values
Materials $840; material waste 10%; labor 12 hours at $48 per hour; tax 6% on materials including waste; no other fee.
Static sample result
Materials with waste: $840.00 + ($840.00 × 10%) = $924.00
Labor: 12 × $48.00 = $576.00
Subtotal before tax: $924.00 + $576.00 = $1,500.00
Taxable materials: $924.00 × 6% = $55.44
Total: $1,500.00 + $55.44 = $1,555.44
Assumptions: the 10% applies only to materials, and the supplied 6% tax applies only to materials after waste. Confirm the real taxable base and rate for the job's jurisdiction.
Every percentage names its base, the arithmetic reconciles to $1,555.44, and tax treatment remains an explicit user-supplied assumption.
Resale break-even price
Static sample values
Purchase cost $120; supplies $35; selling fee 13% of sale price plus $0.30; target profit $50; shipping excluded.
Break-even sale price for the target: $205.30 ÷ 0.87 = $235.98
At $235.98, the 13% fee is about $30.68; adding the $0.30 fixed fee leaves about $205.00 after fees, which covers $155 of costs and the $50 target profit. Shipping, tax, returns, promoted-listing fees, and rounding rules are not included.
The calculation solves the percentage fee against the sale price instead of simply adding 13% to costs, and it names every excluded cost.
Why this helps
Where this task gets hard
A total can be wrong even when every individual number looks plausible. Waste may be applied to labor instead of materials, tax may be charged to the wrong base, or a percentage fee may be mistaken for a fixed amount. A polished estimate does not make hidden arithmetic trustworthy.
The calculator handles a small set of common totals. It uses labeled numbers, follows a reviewed formula, and shows the math in ordinary notation. It is not a spreadsheet, and it never fills in a rate you did not provide.
How it works
From source to finished work
After signing in, choose a supported calculation and enter labeled values with their units.
Review the result, assumptions, field-level validation, and Show the math explanation.
Change a value locally, print the result, or save the calculation result with the related work.
What you can bring
Nonnegative numeric amounts, percentages, quantities, rates, and hours within documented field limits
Built-in calculation cards with reviewed formulas and visible math
Values supplied in text or extracted from a file for review before calculation
Important limits
You cannot write your own formulas or run code. This calculator is not a spreadsheet.
Taxability, rates, fees, measurements, and quantities are user-supplied assumptions and must be checked for the real jurisdiction and job.
The calculator rejects missing numbers and values outside its supported range, but it cannot know whether the numbers you entered are true or complete.
Privacy
Calculation values remain part of your private work and are not published as a public calculator submission.
After authentication, use amounts and quantities without customer account numbers or payment-card data. Saved results retain the labeled inputs and math needed to understand them later.
The examples on this page are static and read-only. Create an account or sign in before using your own material.