How do I choose resistor values for a loaded voltage divider?
Size the divider's own current well above what the load draws, and the output stays close to your target. Say how much stiffer you want it than the load and this page gives you R1/R2 — plus what the buyable pair actually delivers. Everything runs in this page; nothing is uploaded.
Size the divider
Enter the supply, the output you want, and the load it has to drive. The bleeder multiple sets how much bigger the divider's own current is than the load's — 10× is a common starting point.
Common questions
How do I choose resistor values for a voltage divider with a load?
Pick R1 and R2 so the current flowing through the divider itself is several times larger than the current the load draws — a common rule of thumb is 10 times. The bigger that ratio, the less the load's own current disturbs the split, so the output stays close to the unloaded value. The trade-off is power: a stiffer divider wastes more of it, all the time, whether the load is connected or not.
What is bleeder current?
The current that flows through R1 and R2 themselves, independent of whatever the load draws. It exists purely to hold the output steady against loading — the name comes from older bleeder resistors placed across a supply to drain it safely, and the term stuck for any divider current kept deliberately higher than the load needs.
Why not just pick a huge bleeder multiple and forget about droop entirely?
Because the quiescent power the divider burns scales directly with the bleeder current, and that current flows all the time, loaded or not — a stiffer divider is a hotter, more wasteful one, especially on a battery-powered design. It is a real trade-off, not a solved problem: pick the smallest multiple that gets the droop you can live with, and if no multiple gets there without excessive power, that load is telling you to use a proper regulator instead.
Is a resistive divider ever the right way to power something with a load?
Only for light, fairly constant loads where a percent or two of droop and some wasted power are acceptable — biasing a sensor, feeding a comparator reference, or a similar low-current job. For anything that draws meaningful or varying current, a resistive divider is a voltage reference, not a regulator, and a proper linear or switching regulator (or at least a unity-gain buffer) is the right tool.