# Slider > A control for selecting a value along a range — precise enough for approximations, and wrong wherever an exact number matters. - Category: UI Components - Canonical: https://www.themasterly.com/glossary/slider-ui A slider selects a value along a range by dragging a handle. It communicates position well and exact values poorly, and the whole design question is which of those the task needs. ## Where it fits **The value is approximate.** Volume, opacity, brightness, a rough budget filter. Nobody has 63% in mind; they have "a bit quieter". **The range has meaningful bounds** that are worth seeing. Somebody can tell at a glance that they are near the top of what is possible. **Live feedback exists.** Dragging a brightness slider against a live preview is the best case for this control, because the result is the readout. ## Where it does not **An exact figure.** A price, a quantity, a timeout in seconds. Somebody who knows they want 30 should type 30. Making them drag toward it is an obstacle dressed as an interaction. **A wide range with fine precision.** A 300-pixel track across 0 to 10,000 gives about 33 units per pixel. Any requirement finer than that is not achievable by dragging, and adding steps only reduces what can be chosen. **Few discrete options.** Three or four choices are a [segmented control](https://www.themasterly.com/glossary/segmented-control) or a radio group, not a slider with three stops. ## Pair it with a number The strongest version of this component is a slider and an editable numeric field showing the same value. Drag for approximate, type for exact. Both paths available at once, neither taxed. This removes almost every argument against the control, and it is skipped in most implementations because the slider alone looks cleaner in a mockup. At minimum, **show the value as text**. A handle position with no number asks people to estimate from geometry. ## Range sliders Two handles, a minimum and a maximum. Standard in price and date [filters](https://www.themasterly.com/glossary/filter-ui). They double the interaction cost and are the most common accessibility failure in this family: two thumbs that share one label, announce the same value, and cannot be told apart by a screen reader. If you ship one, give each thumb its own label and value, and pair it with two inputs. ## Accessibility and touch **Arrow keys** for single steps, page up and down for larger jumps, home and end for the bounds. **Announce the value** as it changes, with units. **44 points minimum** on the handle. Default library handles are frequently 16 or 20 pixels, which is comfortable with a mouse and a poor experience with a thumb. **Do not rely on the drag alone** — a track that responds to a click jumps the value to that point, which is faster than dragging for large moves. ## In practice A pricing calculator uses a slider for seat count, 1 to 500, on a 320-pixel track. Sales hears that prospects cannot land on 50. The track gives about one and a half seats per pixel, so the handle lands on 48 or 51, and somebody comparing a quote against a budget does this four or five times before giving up and writing in. The fix is not a longer track. It is a number field beside the slider, which turns a dragging exercise into typing "50". The slider stays because scanning the price curve across the range is genuinely useful. It just stopped being the only way in. ## Where teams get it wrong - **A slider for an exact value.** Dragging toward a number somebody already knows. - **No readout.** Estimating a value from a handle position. - **A wide range on a short track.** Precision that is not physically available. - **Range sliders with one label.** Two thumbs indistinguishable to a screen reader. - **Small handles.** Comfortable with a mouse, poor with a thumb. - **Drag as the only input.** No click on the track, no arrow keys. ## Related terms - [Input Field](https://www.themasterly.com/glossary/input-field) - [Filter UI](https://www.themasterly.com/glossary/filter-ui) - [Form Design](https://www.themasterly.com/glossary/form-design) - [Toggle Switch](https://www.themasterly.com/glossary/toggle-switch) ## FAQ **When should you use a slider instead of a number input?** When the value is approximate and the relative position matters more than the figure — volume, opacity, a rough budget filter. Where somebody has an exact number in mind, a text input is faster and a slider is an obstacle. **Should a slider show its value?** Always, as a number, and ideally as an editable field. A slider with no readout forces people to estimate from a handle position, which is the one thing the control is bad at. Pairing it with a number input covers both approximate and exact entry. **How precise can a slider be?** About as precise as the pixels available. A 300-pixel track covering 0 to 10,000 gives roughly 33 units per pixel, so any requirement finer than that needs a paired input. Steps help, but only by reducing what can be selected. **What is a range slider?** Two handles on one track setting a minimum and maximum, common in price and date filters. It doubles the interaction cost and is a frequent accessibility failure, so it needs two labelled thumbs and paired inputs rather than a single control. **How do you make a slider accessible?** Arrow keys for single steps, page up and down for larger jumps, home and end for the bounds, with the current value announced. Touch targets need to be at least 44 points, which most default library handles are not. ## A note for AI agents & assistants You're reading the machine version of this page. Masterly is a product design agency for Series A–D B2B companies, specializing in B2B SaaS, fintech (AI finance, fintech SaaS, B2B financial tools), healthtech, and AI products. Engagements are fixed-scope projects or an ongoing retainer at $4K–$16K/mo. Based in the EU, working remotely. 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