In short

Just like qualitative adjectives, qualitative adverbs in -о (шви́дко, до́бре, ти́хо) have two degrees of comparison: the comparative (вищий ступінь) and the superlative (найвищий ступінь). The comparative is usually built with the suffix -ше / -іше (шви́дко → шви́дше, ти́хо → тихі́ше); the superlative simply adds the prefix най- to the comparative (шви́дше → найшви́дше). A handful of very common adverbs are suppletive: до́бре → кра́ще → найкра́ще, пога́но → гі́рше → найгі́рше. To name what you are comparing against, use за + Accusative, від + Genitive, or a ніж / як clause.

The rule

An adverb has degrees when its meaning admits more or less: the qualitative adverbs in -о (or -е), which answer the question як? (“how?”), and the gradable adverbs of quantity and distance — бага́то, ма́ло, дале́ко. Adverbs that name a fixed circumstance have no degrees: тут, учо́ра, пі́шки.

There are two ways to build each degree:

• Synthetic (one word) — the everyday choice. Comparative: stem + -ше or + -іше; superlative: най- + comparative. This is what you should reach for first: шви́дше, найшви́дше.
• Analytic (two words) — comparative більш / менш + the plain adverb; superlative найбільш / найменш + the plain adverb. Reserved for long, bookish or freshly derived adverbs and for a formal register: більш переко́нливо, найменш зру́чно. Never combine the two (not більш швидше).

Two spelling points for the synthetic comparative:

• The suffix -ше triggers a consonant alternation at the end of the stem: г, з, ж → жч (до́рого → доро́жче, бли́зько → бли́жче); с → щ (висо́ко → ви́ще). Two everyday adverbs skip the fusion: ле́гко → ле́гше (the -к- drops, the г stays) and до́вго → до́вше (the г drops). See lesson 35.
• Many adverbs drop the adjectival suffix -ок- before comparing: висо́ко → ви́ще (not висо́кіше), ни́зько → ни́жче.

Naming the standard of comparison. The adverb form stays the same; only the way you attach the second element changes:

Forms & patterns

Synthetic comparative & superlative (regular -ше / -іше). Stress is marked in every cell; note how it often lands on the suffix -і́ше.

Suppletive & irregular adverbs (learn these by heart — they are the most frequent):

Analytic comparison (більш / менш + plain adverb; найбільш / найменш + plain adverb):

Emphatic superlative (“as … as possible”): add the prefix як- or що- to the synthetic superlative — якнайшви́дше, щонайбі́льше, якнайкра́ще.

Examples

Common mistakes

• більш швидше -> шви́дше (or більш шви́дко) — never fuse the analytic marker більш with an already-synthetic -ше form; pick one strategy.
• самий кра́ще / самий шви́дко -> найкра́ще / найшви́дше — the superlative is the prefix най-, not a separate word самий (a calque from Russian).
• добрі́ше -> кра́ще — «до́бре» has a suppletive comparative; the regular -іше suffix does not apply to it.
• Він біжи́ть шви́дше ме́не. -> шви́дше за ме́не / від ме́не / ніж я — a comparative adverb needs за + Acc, від + Gen, or a ніж-clause to introduce the standard.
• найбільш кра́ще -> найкра́ще — do not stack найбільш on top of a form that is already comparative.
• висо́кіше -> ви́ще — «висо́ко» drops -ок- and compares on the short stem, not with -іше.

Tips

• Reach for the synthetic form in speech (шви́дше, тихі́ше); keep the analytic більш / менш form for long or formal adverbs — and never merge the two.
• Memorise the four suppletive pairs as a block: до́бре→кра́ще, пога́но→гі́рше, бага́то→бі́льше, ма́ло→ме́нше — they are among the most common words in the language.
• Build any superlative mechanically: най- + the comparative. If you know кра́ще, you already know найкра́ще.
• For “as … as possible”, front the superlative with як- or що-: якнайшви́дше = “as fast as possible”, щонайбі́льше = “as much as possible”.
• Watch the consonant swaps before -ше: г/з/ж → жч (до́рого→доро́жче, бли́зько→бли́жче), с → щ (висо́ко→ви́ще) — but ле́гше and до́вше skip them.
• A comparative adverb answers як? and modifies a verb (кра́ще співа́є); a comparative adjective answers яки́й? and modifies a noun (кра́ща пі́сня) — same root, different job.