How the calculation works
An unloaded divider gives Vout = Vin × R2 / (R1 + R2). If something with
input resistance RL is connected to the output, R2 is effectively in parallel with it
(R2 || RL), which pulls the output down. Enter the load and the calculator accounts for it.
The calculator tries every standard value in your range as R2, finds the ideal R1 for it, and checks the standard values on either side. With "up to 3" selected, it also tries making either resistor out of two parts in series or in parallel. That often gets within a fraction of a percent using only E12 or E24 values you already have. Results are ranked by error, then by fewer parts, then by lower current.
Reading the results
- Error is the nominal output compared with your target, assuming perfect resistors.
- With tolerance is the worst-case output range when each resistor is independently at the edge of its tolerance. For precise references, this matters more than the nominal error.
- Current is drawn from Vin all the time. Battery-powered circuits usually want it small, so they use higher resistances.
- Max power is the highest dissipation in any single resistor. A ⚠ appears above 0.1 W, the rating of many 0603 SMD parts.
Choosing a resistance range
Higher resistances waste less current, but they make the output weaker. Loads, leakage and ADC sampling capacitors disturb it more easily. If the divider feeds an ADC, check the maximum source impedance in the datasheet. The divider's output impedance is R1 and R2 in parallel. A capacitor from the output to ground can also help with sampling ADCs.
Standard values
Each series repeats in every decade (×1, ×10, ×100 …). E24 values are the common 5% and 1% range, and E96 is the standard 1% range:
E24
1.0 · 1.1 · 1.2 · 1.3 · 1.5 · 1.6 · 1.8 · 2.0 · 2.2 · 2.4 · 2.7 · 3.0 · 3.3 · 3.6 · 3.9 · 4.3 · 4.7 · 5.1 · 5.6 · 6.2 · 6.8 · 7.5 · 8.2 · 9.1
E96
1.0 · 1.02 · 1.05 · 1.07 · 1.1 · 1.13 · 1.15 · 1.18 · 1.21 · 1.24 · 1.27 · 1.3 · 1.33 · 1.37 · 1.4 · 1.43 · 1.47 · 1.5 · 1.54 · 1.58 · 1.62 · 1.65 · 1.69 · 1.74 · 1.78 · 1.82 · 1.87 · 1.91 · 1.96 · 2.0 · 2.05 · 2.1 · 2.15 · 2.21 · 2.26 · 2.32 · 2.37 · 2.43 · 2.49 · 2.55 · 2.61 · 2.67 · 2.74 · 2.8 · 2.87 · 2.94 · 3.01 · 3.09 · 3.16 · 3.24 · 3.32 · 3.4 · 3.48 · 3.57 · 3.65 · 3.74 · 3.83 · 3.92 · 4.02 · 4.12 · 4.22 · 4.32 · 4.42 · 4.53 · 4.64 · 4.75 · 4.87 · 4.99 · 5.11 · 5.23 · 5.36 · 5.49 · 5.62 · 5.76 · 5.9 · 6.04 · 6.19 · 6.34 · 6.49 · 6.65 · 6.81 · 6.98 · 7.15 · 7.32 · 7.5 · 7.68 · 7.87 · 8.06 · 8.25 · 8.45 · 8.66 · 8.87 · 9.09 · 9.31 · 9.53 · 9.76
About this calculator
Standard values follow IEC 60063. E48, E96 and E192 are generated from the standard formula, with E192's single exception (9.20), and checked against the published E96 table. The search is exhaustive over your range. Its answers are tested against a brute-force reference that tries every combination. Everything runs in your browser.