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268+ free online tools for PDF, images, SEO, developers, color, and productivity. Fast, browser-based, and private — no signup, no installs, no limits. Search above or browse by category below.
Total tools26810.8K total uses
Categories13Active categories
Most usedJSON Formatter4.1K uses
Recently addedExperiment RandomizerNewest tool
Heat Transfer Calculator
Calculate heat transfer by conduction (Fourier), convection (Newton), radiation (Stefan–Boltzmann), overall U-value, and composite wall assemblies. Enter geometry, temperatures, and material properties — get heat rate in W, kW, and BTU/hr with thermal resistance. Metric and imperial units. Free, browser-based.
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Thermal Expansion Calculator
Calculate linear, area, and volume thermal expansion from temperature change. ΔL = αL₀ΔT, ΔA = 2αA₀ΔT, ΔV = 3αV₀ΔT. Bimaterial gap mode for differential expansion between two materials. Material presets for steel, aluminum, concrete, and copper. Metric and imperial units. Free, browser-based.
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Gear Ratio Calculator
Calculate gear ratio, output RPM, and torque multiplier for spur gear trains. Single-stage, compound 2-stage, RPM solver, and tooth-count finder for target ratios. Enter driver and driven tooth counts — get speed reduction and ideal torque gain. Free, browser-based.
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Safety Factor Calculator
Calculate safety factor, margin of safety, and utilization from strength and stress or load and capacity. Modes: SF from stress, SF from load, allowable stress, required strength, and design pass/fail check. Material yield presets. Metric (MPa, kN) and imperial (ksi, lbf). Free, browser-based.
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Scientific Notation Converter
Convert numbers to and from scientific notation, e-notation, and engineering notation. Enter decimals (299792458), e-notation (1.23e-5), or 1.23 × 10^5 format. Get normalized scientific, Unicode superscript, engineering (×10³), and decimal forms. Adjustable significant figures. Free, browser-based.
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Significant Figures Calculator
Count significant figures, round to N sig figs, and add, subtract, multiply, or divide with correct precision rules. Enter decimals, trailing zeros, or scientific notation. Free, instant, browser-based.
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Measurement Uncertainty Calculator
Combine and propagate measurement uncertainty with root-sum-of-squares (RSS). Add, subtract, multiply, or divide values with ± uncertainties, convert percent uncertainty, and compute expanded uncertainty U = k·u. Free, instant, browser-based.
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Error Percentage Calculator
Calculate percent error, absolute error, relative error, and percent difference between measured and accepted values. Step-by-step formulas for physics and chemistry lab reports. Free, instant, browser-based.
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Standard Solution Calculator
Prepare analytical standard solutions from solid or stock. Calculate mass to weigh, stock aliquot for dilution (C₁V₁=C₂V₂), and verify actual molarity. Step-by-step lab procedure for volumetric flasks. Free, browser-based.
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Lab Dilution Calculator
Plan lab dilutions with pipette volumes, 1:N ratio dilutions, and serial dilution schemes. Get C₁V₁=C₂V₂ stock aliquots, sample and diluent volumes, and step-by-step bench procedures in µL, mL, or L. Free, browser-based.
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Microliter Converter
Convert microliters (µL) to milliliters, liters, nanoliters, cubic centimeters, and more. Instant lab volume conversions with all units shown at once. Free, browser-based.
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Sample Size Calculator
Calculate sample size for surveys, mean estimates, A/B tests, and two-group comparisons. Set confidence level, power, margin of error, and effect size. Step-by-step formulas. Free, browser-based.
Used 0 times•Updated never