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Online calculators · Page 9
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- Rafter length calculatorFind the sloping rafter line from rise, horizontal run and overhang: length = (run + overhang) × √(1 + (rise/run)²).
- RAID capacity calculatorEstimate usable RAID capacity from equal-size drives and your chosen stripe, mirror or parity layout.
- Ratio calculatorSimplify a whole-number ratio and see each share.
- Rebar material calculatorCount straight bars in two directions with edge bars and a maximum spacing.
- Rebar weight calculatorMultiply total reinforcing-bar length by the supplier’s mass per metre.
- Rectangle calculatorRectangle area = length × width. Perimeter = 2 × (length + width). Diagonal = √(length² + width²).
- Recurring revenue calculatorMonthly recurring revenue = active subscriptions × average monthly recurring revenue per subscription.
- Reference angle calculatorFind the angle to the nearest horizontal axis after reducing the given angle to one turn.
- Refinance calculatorCompare the remaining payment schedule with a new loan for the same balance and your refinance costs.
- Rent calculatorSubtract other spending, planned savings and non-rent housing costs from take-home income.
- Rent vs buy calculatorCompare home equity after sale with the renter’s investment balance while matching both scenarios’ cash-flow budgets.
- Rental property roi calculatorCompare rental cash flow, cash-on-cash return and capitalization rate using your rent and expense assumptions.
- Resin print cost calculatorAdd resin volume cost, an explicit loss allowance, washing consumables and other print costs.
- Resistance calculatorResistance = voltage magnitude ÷ current magnitude.
- Resistor capacitor circuit calculatorCalculate an RC time constant τ = RC and ideal capacitor charging and discharging voltages.
- Retaining wall calculatorCount block courses and pieces for a straight, level, rectangular retaining-wall face.
- Retirement calculatorProject a retirement balance from current savings and monthly contributions, then adjust it for your inflation assumption.
- Retirement withdrawal calculatorEstimate how long savings support a fixed withdrawal at a constant annual return.
- Return on equity calculatorReturn on equity = net income ÷ average shareholder equity × 100.
- Rhombus calculatorRhombus area = diagonal one × diagonal two ÷ 2. Each side is half the hypotenuse formed by the two diagonals.
- Right triangle calculatorHypotenuse = √(leg one² + leg two²). Area = leg one × leg two ÷ 2.
- RLC impedance calculatorFind sinusoidal series RLC impedance: Z = R + j(2πfL − 1/(2πfC)).
- ROAS calculatorROAS = attributed revenue ÷ advertising spend.
- Roof pitch calculatorPitch as rise per 12 run = rise ÷ horizontal run × 12. Angle = arctan(rise ÷ run).
- Roofing calculatorConvert horizontal roof projection area to sloping area using √(rise² + run²)/run.
- Room furniture plannerPlace rectangular furniture by dimensions and coordinates, with a live floor plan and overlap checks.
- Root calculatorFind square, cube and higher real roots.
- Rounding calculatorRound a decimal exactly to the chosen decimal place, with halfway values rounded away from zero.
- Rule of 72 calculatorCompare the rule of 72’s quick doubling estimate with exact annual compound growth.
- Sales tax calculatorTotal with sales tax = taxable price × (1 + tax rate ÷ 100).
- Sample size calculatorPlan a proportion estimate using n₀ = z²p(1 − p)/error², with optional finite-population correction.
- Savings goal calculatorTurn a savings target into a monthly contribution.
- Scale calculatorScale a length by a multiplier and see how area and volume change.
- Scientific calculatorType a scientific expression, with degrees or radians.
- Scientific notation calculatorWrite a decimal as a coefficient from 1 up to 10 times a power of ten, without losing its numeric value.
- Sector area calculatorSector area = π × radius² × angle ÷ 360 when the angle is in degrees.
