Flip-Flop Calculator
Calculate SR, JK, D and T flip-flop next state, truth table, excitation table and clock sequence for digital logic and sequential circuits.
🔁 Sequential Logic Rule: A flip-flop stores one bit. Combinational gates respond immediately, but flip-flop output changes with the clock. Use this with the Truth Table Generator, Logic Gate Calculator, Boolean Algebra Calculator and K-Map Solver.
🔁 Inputs + Clock → Flip-Flop → Next State
Flip-Flop Type
Present State Q
J Input
K Input
JK with J=K=1 toggles the output on the active clock edge.
Presets:
Truth Table Type
Active Clock
Truth tables show the next state Q⁺ for each input combination and present state Q.
Quick:
Excitation Table Type
Transition Example
Excitation tables answer the reverse question: which input is needed to force a selected Q → Q⁺ transition?
Flip-Flop Type
Initial Q
Input Sequence
For T flip-flop, enter T values like: 1,1,0,1. T=1 toggles, T=0 holds.
Examples:
📐 Formula / Characteristic Reference
D Flip-Flop
Q⁺ = D
T Flip-Flop
Q⁺ = T ⊕ Q
JK Flip-Flop
Q⁺ = JQ̅ + K̅Q
SR Flip-Flop
Q⁺ = S + R̅Q, with S=R=1 invalid
📋 Quick Reference
SR Inputs
S=0 R=0hold
S=1 R=0set
S=0 R=1reset
S=1 R=1invalid
JK Inputs
J=0 K=0hold
J=1 K=0set
J=0 K=1reset
J=1 K=1toggle
Common Use
Dregister
Tcounter
JKuniversal
SRset/reset
📚 Engineering Notes
Flip-flop vs gateA logic gate has no memory. A flip-flop stores the previous state and updates only on the clock event.
D flip-flop is most commonD flip-flops are widely used for registers, pipelines, counters and synchronous digital design.
SR invalid stateFor an active-high SR flip-flop, S=1 and R=1 is normally avoided because both set and reset are requested at the same time.
Excitation table useExcitation tables are useful when designing counters and state machines from a desired state transition table.
What is a Flip-Flop Calculator?
A flip-flop calculator helps you find the next output state of SR, JK, D and T flip-flops. It is useful for digital electronics, counters, registers, sequential circuits and state machine design.
How to use this calculator
Use the next-state tab when you know the present state and inputs. Use the truth table tab to compare all input combinations. Use the excitation table when you know the desired Q to Q⁺ transition and need the required flip-flop inputs.
❓ Frequently Asked Questions
A flip-flop is a clocked one-bit memory element. It stores a binary state and updates output on the selected clock edge depending on its input conditions.
A latch is generally level-sensitive, meaning it can follow input while enable is active. A flip-flop is usually edge-triggered and changes only on a clock edge.
For active-high SR: S=0 R=0 holds, S=1 R=0 sets Q to 1, S=0 R=1 resets Q to 0, and S=1 R=1 is normally invalid.
For JK: J=0 K=0 holds, J=1 K=0 sets, J=0 K=1 resets, and J=1 K=1 toggles the output.
A T flip-flop toggles when T=1 and holds when T=0. It is commonly used for counters and frequency division.
A D flip-flop stores the D input on the active clock edge. It is commonly used in registers, memory elements, shift registers and synchronous circuits.
An excitation table shows the required input values to move from present state Q to desired next state Q⁺. It is often used in counter and sequential circuit design.
Setup time is the minimum time input must be stable before the clock edge. Hold time is the minimum time input must remain stable after the clock edge.