calc.engineer
engineer.calc/calc88 free engineering calculators: RF link budgets, LoRa/Meshtastic, PCB, solar, homelab. Keyless.
Tools · 89
Calculate free-space path loss (FSPL) in decibels using the ITU-R P.525 standard formula. Given a frequency in MHz and distance in kilometres, returns the expected signal attenuation in an ideal line-…
Compute a full RF link budget from transmitter power, frequency, distance, and antenna gains. Calculates EIRP, free-space path loss (ITU-R P.525), received power at the receiver, and link margin relat…
Calculate physical dimensions of a dipole antenna for a given frequency. Returns half-wave or quarter-wave element length in metres, feet, and inches. A half-wave dipole is the most common resonant an…
Calculate PCB microstrip trace width for a target characteristic impedance using the Hammerstad-Jensen closed-form equations. Given target impedance (Z0), substrate dielectric constant (er), substrate…
Convert a power level in dBm to milliwatts, watts, dBW, and RMS voltage across a given impedance. dBm is the standard unit for RF power referenced to 1 milliwatt. This tool is essential when interfaci…
Calculate the cascaded noise figure of a multi-stage receiver chain using the Friis formula. Each stage has a noise figure and gain in dB. The first stage dominates overall system noise, which is why …
Convert between VSWR, return loss, and reflection coefficient — provide any one parameter and get all related impedance-mismatch metrics. Computes VSWR (voltage standing wave ratio), return loss in dB…
Design a Pi-topology resistive attenuator pad. Given a desired attenuation in dB and characteristic impedance (default 50 ohm), computes the three resistor values for a symmetrical Pi-pad network. The…
Design a Tee-topology resistive attenuator pad. Given a desired attenuation in dB and characteristic impedance (default 50 ohm), computes the three resistor values for a symmetrical T-pad network. The…
Calculate the Fresnel zone radius at the midpoint of a radio link. Given frequency in MHz, link distance in kilometres, and zone number (1-5), returns the Fresnel zone radius in metres and feet, plus …
Convert between radio frequency and wavelength. Provide either frequency in MHz or wavelength in metres, and get the full set of equivalent values: frequency in MHz and GHz, wavelength in metres, cent…
Generate a complete SPICE netlist from a parameterized template. Supports common circuit topologies: low-pass RC filter, voltage divider, common emitter amplifier. Returns a ready-to-simulate netlist …
Run a SPICE circuit simulation directly in the worker. Accepts a standard SPICE netlist and performs operating-point (.op), DC sweep (.dc), AC frequency sweep (.ac), or transient (.tran) analysis usin…
Calculates LoRa packet time-on-air using the Semtech AN1200.13 formula. Computes symbol duration, preamble time, payload symbol count, effective data rate, and the minimum transmission interval for 1%…
Computes LoRa link SNR margin by comparing received power against the noise floor and the spreading-factor-dependent demodulation threshold from the Semtech SX1276 datasheet. Calculates receiver noise…
Estimates Meshtastic or LoRa mesh channel utilization percentage based on node count, message rate, and per-packet airtime. Determines how much of the shared radio channel is occupied and computes the…
Estimates LoRa maximum communication range by computing the free-space path loss (FSPL) link budget and applying terrain-dependent correction factors. Calculates total link budget from transmit power,…
Calculates LoRa receiver sensitivity from spreading factor, bandwidth, and noise figure using the Semtech SX1276 datasheet SNR thresholds. Computes the noise floor from thermal noise density (-174 dBm…
Calculates LoRa duty cycle budget for EU868, US915, AS923, and AU915 regulatory regions. Computes maximum messages per hour, minimum transmission interval, and effective data rate under regional duty …
Estimates Meshtastic node communication range using real hardware profiles and firmware channel presets. Combines device-specific TX power and antenna gain (Heltec V3, RAK WisBlock, T-Beam, T-Beam Sup…
Checks EIRP (Effective Isotropic Radiated Power) compliance against regional regulatory limits for LoRa and Meshtastic operation. Computes EIRP from transmit power, antenna gain, and cable loss, then …
Calculates Meshtastic node power consumption and battery runtime using device-specific power profiles and firmware role-based duty cycling. Models sleep, RX, and TX current draw for Heltec V3, RAK Wis…
Recommends optimal LoRa spreading factor, bandwidth, and TX power based on target range, terrain, and optimization priority. Iterates through all SF (7-12) and BW (125/250/500 kHz) combinations, compu…
Calculate usable ZFS pool capacity for any RAID level including stripe, mirror, raidz1, raidz2, and raidz3. Computes raw capacity, parity overhead, data disk count, usable terabytes after ZFS metadata…
Calculate recommended RAM and ARC sizing for a ZFS storage pool based on workload type, pool size, deduplication status, and L2ARC cache size. Computes minimum and recommended RAM in gigabytes, ARC ta…
Calculate maximum TCP throughput using the Bandwidth-Delay Product (BDP) formula. Given link bandwidth and round-trip latency, computes the BDP (maximum in-flight data), achievable throughput with a g…
Calculate the optimal MTU for a WireGuard VPN tunnel interface with a detailed overhead breakdown. Accounts for WireGuard header (32 bytes), outer IP header (20 bytes IPv4 or 40 bytes IPv6), UDP heade…
Calculate IPv4 subnet details from CIDR notation. Parses a CIDR block (e.g. 192.168.1.0/24) and returns the network address, broadcast address, subnet mask, wildcard mask, first and last usable host a…
Estimate RAID array IOPS performance and latency for ZFS and traditional RAID configurations. Calculates maximum read IOPS, write IOPS (accounting for write penalty/amplification per RAID level), blen…
Calculate total power consumption, electricity cost, and circuit requirements for a homelab. Enter each device's wattage to get daily/monthly/yearly kWh and cost at your local electricity rate. Accoun…
Estimate the cooling load (BTU/hr) for a homelab or server closet based on equipment wattage, room dimensions, insulation quality, and solar exposure. All electrical power converts to heat — this tool…
Quick rack space and weight sizing calculator for homelab and small data center racks. Enter your devices with their height in rack units, weight, and wattage to get total utilization, remaining free …
Plan and validate network link capacity for homelab workloads. Determine whether a 1G, 2.5G, 10G, or faster link can handle your concurrent streams (VMs, backups, media, iSCSI). Calculates effective b…
Estimate steady-state thermal behaviour of a rectangular enclosure (server rack, electronics housing, equipment cabinet) using a lumped-parameter energy balance with natural-convection and radiation c…
Analyze a forced-convection fin-array heatsink using established channel-flow correlations (developing laminar Nusselt, fin efficiency tanh(mH)/mH, parallel-plate friction). Computes base-to-air therm…
Estimate PCB component temperatures by solving a thermal resistance network (thermal↔electrical analogy) with the built-in MNA solver. Each component gets a junction node (package θjb from a typical-d…
Calculates battery runtime and energy capacity given cell capacity in mAh, nominal voltage, and average current draw. Accounts for real-world discharge efficiency (Peukert-adjacent derating) to produc…
Determines the minimum AWG (American Wire Gauge) conductor size for a given current, voltage, one-way cable distance, and maximum allowable voltage drop percentage. Supports copper and aluminum conduc…
Sizes an off-grid solar power system by calculating the number of panels and battery bank capacity required for a given daily energy consumption. Accounts for system losses (inverter, wiring, charge c…
Estimates UPS (Uninterruptible Power Supply) backup runtime from battery specifications and connected load. Takes VA rating, watt rating, load in watts, and battery configuration (count, voltage, amp-…
Converts battery capacity from milliamp-hours (mAh) to watt-hours (Wh), kilowatt-hours (kWh), and joules (J) given the nominal cell voltage. This is the most common battery unit conversion needed when…
Converts electrical power in watts to current in amps (and milliamps) for a given voltage, using the DC power formula P = V * I. Also computes the implied load resistance via Ohm's law (R = V / I) ass…
Calculates voltage drop across a conductor run given current, wire length, AWG gauge, system voltage, and conductor material (copper or aluminum). Computes round-trip resistance, voltage drop in volts…
Estimates battery charge time given capacity in mAh, charge current in mA, charger efficiency, and initial state of charge. Accounts for real-world charging losses (typically 80-90% efficient) to prod…
Calculates total daily energy consumption from an appliance list — the critical first step before sizing solar panels or batteries. Enter each appliance with its wattage, hours of daily use, and quant…
Calculates solar system return on investment, payback period, and levelized cost of energy (LCOE). Models year-by-year savings accounting for panel degradation, utility rate inflation, federal Investm…
Calculates how many days a battery bank can sustain loads without solar input — critical for off-grid and backup power sizing. Accounts for depth of discharge, round-trip efficiency (lithium vs lead-a…
Calculates optimal solar panel string and MPPT configuration based on panel electrical specs, inverter/charge-controller MPPT limits, and site temperature extremes. Applies temperature coefficients to…
Compares total cost of ownership between a fuel generator and a solar+battery system over a configurable time horizon. Calculates yearly and cumulative costs for generator-only, solar-only (amortized)…
Determine minimum wire gauge using NEC Table 310.16 ampacity ratings with full derating. Looks up base ampacity for copper or aluminum conductors at 60°C, 75°C, or 90°C insulation rating, then applies…
Size a DC-to-AC inverter for off-grid solar, battery backup, or mobile power systems. Computes the required continuous VA rating from total load watts and power factor, estimates surge capacity for mo…
Turn a SPICE netlist into a fab-ready 2-layer PCB: assigns real footprints (0805, TO-92, DO-35, DIP-8, headers, LED, radial-cap), auto-places components (connectivity-aware; or use your own placement)…
Calculates output voltage, current draw, and power dissipation for a resistive voltage divider. Given an input voltage Vin and two resistor values R1 (upper) and R2 (lower), computes Vout = Vin * R2 /…
Computes the cutoff frequency, time constant, impedance, and phase shift of a first-order RC filter. Supports both lowpass and highpass topologies. The cutoff frequency is f = 1/(2*pi*R*C) where the s…
Calculates the resonant frequency of an LC circuit, along with optional Q factor and bandwidth when series resistance is provided. The resonant frequency f0 = 1/(2*pi*sqrt(L*C)) is where inductive and…
Designs an L-network impedance matching circuit between two real impedances at a given frequency. Computes the required shunt and series reactive components (inductor and capacitor) to transform the s…
Calculates the minimum PCB trace width for a given current using the IPC-2221 standard formula. The IPC-2221 empirical equation relates current capacity to cross-sectional area and temperature rise: I…
Solves Ohm's Law and the power equation given any two of four electrical quantities: voltage (V), current (I), resistance (R), and power (P). Uses V=IR, P=VI, P=I^2R, and P=V^2/R to derive the missing…
Decodes 4-band or 5-band resistor color codes into resistance value, tolerance, and min/max range. Accepts an ordered array of color names (left-to-right as printed on the resistor body). Supports sta…
Calculates the current-limiting resistor for driving one or more LEDs in series from a DC supply. Computes the exact resistance from R = (Vsupply - n*Vf) / I, then selects the nearest E24 standard res…
Calculates timing parameters for the ubiquitous NE555 / LM555 timer IC in astable (free-running oscillator) and monostable (one-shot pulse) modes. In astable mode, computes frequency, period, duty cyc…
Calculate voltage gain and output for operational amplifier circuits in inverting, non-inverting, and differential configurations. For inverting: Av = -Rf/Ri with input impedance equal to Ri. For non-…
Calculates RC capacitor charge timing, energy storage, and transient voltages. Given resistance, capacitance, supply voltage, and optional initial voltage, computes the RC time constant (τ = R×C), tim…
Calculate PCB via current-carrying capacity using the IPC-2221 standard. A plated via is a hollow copper cylinder whose cross-sectional area is the annular ring of plating: A = pi * (D - t) * t, where…
Select bypass and bulk decoupling capacitors for IC power supply pins. Computes the target PDN (Power Distribution Network) impedance from supply current, voltage, and allowable ripple using Z_target …
Compute logarithms of a positive number in any base. Returns the custom-base logarithm, natural logarithm (ln), common logarithm (log10), and binary logarithm (log2). Useful for signal processing (dec…
Count significant figures in a number and optionally round to N significant figures. Accepts the number as a string to preserve trailing zeros (e.g. '1.200' has 4 sig figs). Applies standard sig fig r…
Convert any number to scientific notation and engineering notation. Returns the coefficient, exponent, a formatted string with Unicode superscripts (e.g. '3.14 × 10²'), and engineering notation where …
Calculate what percentage one number is of another. Given a value and a total, returns the percentage, decimal form, and simplified fraction. For example, 3 out of 4 yields 75%, 0.75, and '3/4'. Commo…
Calculate the percentage change between an old value and a new value. Determines whether the change is an increase or decrease, the absolute change, and the percentage change. Essential for financial …
Compute the result of raising a base to an exponent (base^exponent). Handles positive and negative exponents, fractional exponents, and zero. Returns the numeric result and a scientific notation strin…
Compute the square root of a non-negative number. Returns the decimal result, whether the input is a perfect square, and a simplified radical form (e.g. '√12' simplifies to '2√3'). For integer inputs,…
Calculate the circumference and area of a circle given either a radius or diameter. Provide one or both; if both are given, radius takes precedence. Returns circumference (C = 2πr), area (A = πr²), an…
Calculate the slope, y-intercept, line equation, angle, and distance between two points in a 2D Cartesian plane. Given coordinates (x1, y1) and (x2, y2), computes slope (rise/run), y-intercept, the eq…
Solve for any side of a right triangle using the Pythagorean theorem (a² + b² = c²). Provide any two of the three sides (a, b, c) and the missing side is computed. Also returns the triangle area (0.5 …
Calculate the p-value for a z-score or t-statistic. Supports one-tailed (left or right) and two-tailed hypothesis tests using either the standard normal distribution or the Student's t-distribution wh…
Calculate the confidence interval for a sample mean. Given a sample mean, sample size, standard deviation, and confidence level, computes the margin of error, lower and upper bounds, critical z-score,…
Calculates total cost including sales tax for a purchase. Given a unit price, tax rate percentage, and optional quantity, computes the subtotal (price times quantity), the tax amount rounded to two de…
Converts compensation between annual salary, monthly pay, weekly pay, and hourly wage. Accepts any of the four pay periods as input and derives all others. Uses configurable hours per week (default 40…
Computes a full loan amortization schedule given principal, annual interest rate, and term in months. Returns the fixed monthly payment, total interest, total payments, and a month-by-month breakdown …
Calculates compound interest growth over time using the formula A = P(1 + r/n)^(nt). Given a principal, annual rate, duration in years, and compounding frequency, returns the future value, total inter…
Calculates a test or exam grade from the number of correct answers and total questions. Returns the percentage score, letter grade, points missed, and GPA points. Supports US grading (A/B/C/D/F with 4…
Calculates area and perimeter for common shapes — rectangle, circle, or triangle — in both imperial and metric units. Returns area in square feet, square meters, and acres, plus perimeter in feet and …
Convert between units across 10 categories: length (m, km, mi, ft, in, yd, nmi), mass (kg, lb, oz, g, ton), volume (l, gal, ml, cup, fl_oz), area (m2, ft2, acre, hectare), speed (mps, kph, mph, knot),…
Convert numbers between hexadecimal, binary, decimal, and octal bases. Accepts any base as input (prefix 0x for hex, 0b for binary, 0o for octal, or plain decimal) and returns all four representations…
Convert between Unix timestamps and human-readable date/time formats. Accepts Unix epoch (in seconds or milliseconds), ISO 8601 strings, or 'now' for the current time. Returns both Unix seconds and mi…
Calculate Body Mass Index (BMI) from weight and height using the WHO standard formula. Supports metric (kg/cm) and imperial (lbs/inches) units. Returns the BMI value, WHO classification (Underweight, …
Calculate tip and split a restaurant bill among multiple people. Given a bill amount, tip percentage, and number of diners, returns the tip amount, total with tip, per-person share, and effective tip …
Calculate the difference between two dates in days, weeks, months, years, and business days. Accepts dates in YYYY-MM-DD format. Returns the absolute difference (order doesn't matter) plus a flag indi…
Resources · 2
calc-engineer://catalog
calc-engineer://chains
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Add to your Claude Desktop / Cursor / Cline MCP config:
{
"mcpServers": {
"calc.engineer": {
"url": "https://calc.engineer/mcp",
"transport": "streamable-http"
}
}
}