Free calculators and tools for electricians, technicians, and engineers. Each calculator is mobile-friendly and shows the formula it’s using — no black-box math.
runtime = (C_eff × DoD) / I ; C_eff = C_rated × (I_rated / I)^(k−1)I_effective = I_base × k_temp × k_groupFill % = (Σ wire areas / conduit area) × 100cost = (W × hours / 1000) × rate_per_kWhI = P / (√3 × V × PF × η) [three-phase motor case]V = I × R ; P = V × IVdrop = k × I × L × (ρ / A)A = (2 × ρ × L × I) / VdropEU = (mA − 4) / 16 × (EU_max − EU_min) + EU_minstep size = EU span ÷ steps ; steps = 2^bitscounts/rev = PPR × decoding ; counter_hz = RPM/60 × PPR × decodingPDU offset = Modicon_1based − 1 ; byte_order determines value interpretationFLA = P / (√3 × V × PF × η)n_sync = 120 × f / p ; n_actual = n_sync × (1 − s)LRA = FLA × Iₐ/Iₙ or LRA = (kVA/HP × HP × 1000) / (√3 × V)t_scan = t_overhead + Σ(n_i × t_i) + t_io + t_commRTD: R = R₀(1 + AT + BT² [+ C(T−100)T³]) · TC: V(T) NIST ITS-90 polynomialsS² = P² + Q² ; P = √3 × V × I × cos φS = √3 × V × I / 1000 ; S_size = Σ(S_i) × diversity × (1 + growth)