Kalkmi Online calculators
English

Free Online Calculators

Calculator descriptions

RC Time Constant Calculator — Charge, Discharge & Tolerances

Explore capacitor charge and discharge, time to a voltage threshold, and timing ranges from resistor and capacitor tolerances.

Rafter Length Calculator — Pitch, Overhang & Ridge

Calculate common rafter line length with roof pitch, horizontal overhang and ridge-board deduction. View the section and print your measurements.

Random Number Generator — One Number or a Unique Sample

Generate one number from a clearly labelled inclusive range, or create, sort, copy and download a larger random sample.

Ratio Calculator

Simplify ratios, scale quantities, split a total and solve proportions exactly. Fractions, editable examples and clear visual comparisons.

Rectangular Tube Load Calculator — RHS & SHS Beam

Check RHS or SHS bending stress, deflection and estimated load capacity for steel, stainless steel or aluminum with simple, fixed or cantilever supports.

Retaining Wall Calculator — Blocks, Gravel, Drainage & Cost

Estimate a segmental retaining wall from editable block geometry. Calculate courses, blocks, pallets, caps, base and drainage aggregate, pipe, fabric, excavation and cost.

Retirement Calculator — Savings & Monthly Income

Estimate savings at retirement from your age, current balance, and monthly contribution. Then refine income, spending, returns, and inflation.

Roof Shingle Calculator — Roof Planes, Bundles & Cost

Plan shingle bundles for multiple roof planes, with pitch, product coverage, starter strips, ridge caps and your material quotes.

Running Pace Calculator — Time, Distance & Splits

Calculate running pace, finish time, or distance with only the two values you know, then optionally build exact even or negative splits.

SWP Calculator — Monthly Withdrawals & Corpus

See how long your corpus funds monthly withdrawals in rupees. Add rising expenses, inspect each payment and compare the order of early returns.

Salary Calculator — Hourly to Annual Pay

Convert hourly, daily, weekly, monthly, or annual gross pay instantly. Optionally adjust schedule, unpaid time, overtime, bonus, and raise.

Sample Size Calculator

Plan completed survey responses, expected invitations and sampling precision. Explore the trade-off between sample size and margin of error.

Text copied
Removal error
Restore error
Calculator published
Calculator unpublished
Feedback sent
Done
Error
Author received:++
Calculator removed

Install as an app

Open the browser menu and choose “Add to Home Screen” or “Install app”.
Kalkmi online calculators

Kalkmi helps you calculate VAT, loans, mortgages, percentages, and more.

Start calculating

This experimental service has no accuracy warranty. Calculator values are never sent; only limited anonymous visit statistics are used.