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GCSE Physics guide

GCSE Physics Equations: Units, Formulae and Working

A board-aware guide to choosing the right relationship, converting units, rearranging formulae, substituting values and checking whether your answer makes sense.

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Current answer

Do you get an equation sheet in GCSE Physics?

Yes — for the current GCSE Physics and Combined Science specifications regulated in England. On 5 May 2026, Ofqual decided that awarding organisations must continue to provide the relevant equations sheet for the remaining lifetime of those specifications, including relevant resits. For these qualifications, the sheet must be published by 1 September in the year before the examination series and supplied as a clean copy with the paper.

“Continue to require exam boards to provide students with formulae and equations sheets.” — Ofqual

This is not one rule for every part of the UK. Wales and Northern Ireland have separate qualification arrangements, while most learners in Scotland take National 5 Physics rather than GCSE Physics.

Use the current official sheet for your awarding organisation, qualification or course, tier and examination year. Separate Physics and Combined Science can use different content or layouts, and some material may be Higher Tier only.

Equation-sheet arrangements across the UK

The phrase “UK GCSE Physics equation sheet” can hide important differences. Start with the nation and qualification you are actually taking.

A nation-by-nation guide to the current scope of equation-sheet advice.

AreaCurrent positionWhat to use

England

For current Ofqual-regulated GCSE Physics and Combined Science specifications, the relevant equations sheet is provided for the remaining lifetime of those specifications, including relevant resits.

Use the current official sheet for your awarding organisation, course, tier and exam year.

Wales

Science qualifications are in transition from September 2026. Updated separate GCSE Physics and the new GCSE The Sciences (Double Award) must not be treated as one identical course.

Use the current WJEC specification and assessment materials for your exact qualification and cohort.

Northern Ireland

Northern Ireland has separate CCEA arrangements. The England decision does not confirm whether every CCEA science qualification supplies a complete equation sheet.

Use the current CCEA materials for your exact Physics or science qualification before relying on any equation sheet or data booklet.

Scotland

Most learners study National 5 Physics rather than a qualification called a Scottish GCSE. National 5 Physics has an official Relationships Sheet.

Use the current Qualifications Scotland course guidance and Relationships Sheet for National 5 Physics.

An equation sheet does not do the thinking for you

For current England specifications, the Department for Education says students are not expected to memorise the usual equations. They are still assessed on understanding and applying the relationships.

OCR summarises the assessment principle clearly:

“Avoid setting questions that can be answered solely by copying information from the sheets.” — OCR

You must choose the relationship

The sheet gives equations, but the question gives the physical situation. You still need to identify the required quantity and decide which relationship connects it to the information provided.

Symbols must match quantities

A number is only useful when you know what it represents. Write each value with its quantity name, symbol and unit before substituting.

Units must be compatible

Kilojoules, minutes, centimetres and prefixed units often need converting before the values can be used together.

Algebra and calculator work still matter

You may need to change the subject, preserve brackets or powers, and enter the whole numerical expression accurately.

The assessed skill set is broad

AQA’s current GCSE Physics specification includes changing the subject, substituting with units, using SI prefixes, interconverting units, judging order of magnitude and using appropriate significant figures.

Physics calculations carry substantial weight

In England, qualification rules require at least 30% of separate GCSE Physics marks to assess mathematical skills. For Combined Science, at least 20% of the whole qualification assesses mathematical skills, distributed across Biology, Chemistry and Physics in a 1:2:3 ratio.

Before you calculate: identify the sheet, target and known quantities

A good setup prevents many errors before the calculator is used. Suppose a question says that a device transfers 18 kJ in 2.5 min and asks for power in watts. Do not begin with the bare numbers 18 and 2.5.

  • Check the official sheet

    Confirm the awarding organisation, qualification title or code, tier and examination year. Do not assume an undated school copy matches your paper.

  • Underline the target

    Identify exactly what the question asks you to find and the unit requested. Here, the target is power in watts.

  • List the known quantities

    Energy transferred, E = 18 kJ; time, t = 2.5 min; power, P = ?.

  • Match every number to a symbol

    Do not substitute a value simply because it appears in the question. In its Summer 2025 Foundation Physics A examiner report, OCR documented a candidate using a supplied distance value where gravitational field strength was required.

  • Choose a relationship that contains the target

    For this example, P = E / t links power to the two known quantities.

  • Look for another unknown

    If the chosen equation still contains a quantity you do not know, the question probably needs an earlier calculation or another piece of information.

The nine-step method for GCSE Physics equations

Use this sequence whenever a calculation question feels complicated. It is a practical study method built from official mathematical-skills requirements and examiner evidence, not an exam-board acronym.

  • 1. Identify

    Underline the required quantity and the unit the answer should use.

  • 2. List

    Write each known quantity with its symbol, value and unit.

  • 3. Select

    Choose an equation that contains the required quantity and the quantities you know.

  • 4. Convert

    Put values into compatible units on separate lines before substitution.

  • 5. Rearrange

    Change the subject so the required symbol stands alone.

  • 6. Substitute

    Replace every symbol with the correctly matched value, using brackets where needed.

  • 7. Calculate

    Enter the complete expression carefully and keep the full calculator value.

  • 8. Round

    Follow any stated significant-figure or decimal-place instruction, normally rounding only at the final step.

  • 9. Check

    Test the unit, magnitude, sign, relationship, reverse substitution and the exact question asked.

Common equation mistakes and the better habit

OCR’s Summer 2025 Foundation Physics A examiner report illustrates that selecting the correct equation is only the beginning. The habits below make errors easier to prevent and trace.

Six common calculation errors and a better habit for each.

Error categoryWhat goes wrongBetter habit

Equation selection

A familiar-looking equation is chosen without checking the quantities.

List the known and required quantities first.

Rearrangement

The correct relationship is selected, but the unknown is not isolated correctly.

Rearrange symbolically before inserting numbers.

Quantity matching

A number is substituted for the wrong symbol.

Write quantity name, symbol, value and unit together.

Unit conversion

Prefixes, minutes, centimetres or compound units are mixed.

Put each conversion on its own line before substitution.

Calculator entry

Brackets, powers, roots or the fraction line are entered incorrectly.

Write the complete substituted expression before entering it once.

Presentation and rounding

The result is rounded too early, lacks a unit or ignores a stated precision.

Keep calculator precision until the final line and state the final unit.

GCSE Physics unit prefixes and conversion factors

A physical quantity is what is measured, such as energy, time, current or mass. A unit is the agreed scale used to express it, such as joules, seconds, amperes or kilograms. An SI unit belongs to the International System of Units, or is derived from SI base units.

A unit prefix changes the scale by a power of ten. The symbol is case-sensitive: M means mega, while m means milli when it is used as a prefix; kilo uses lower-case k.

The National Physical Laboratory explains that changing the size of the unit also changes the number used with it while the physical measurement stays the same. For example: 18 kJ = 18,000 J, 2.5 min = 150 s, and 4.5 mm = 0.0045 m.

Common GCSE Physics prefixes, symbols, powers of ten and examples.

PrefixSymbolFactorExample

tera

T

10¹²

1 TJ = 10¹² J

giga

G

10⁹

1 GW = 10⁹ W

mega

M

10⁶

1 MJ = 10⁶ J

kilo

k

10³

1 kJ = 10³ J

centi

c

10⁻²

1 cm = 10⁻² m

milli

m

10⁻³

1 mA = 10⁻³ A

micro

µ

10⁻⁶

1 µs = 10⁻⁶ s

nano

n

10⁻⁹

1 nm = 10⁻⁹ m

Four worked GCSE Physics equation examples

These are original teaching examples rather than reproduced examination questions. Each one shows the quantities, any conversion, the relationship, the algebra, the calculation, the unit and a quick check.

Recommendation

Power from energy and time

Problem: A device transfers 18 kJ of energy in 2.5 min. Calculate its mean power.

Known quantities: E = 18 kJ; t = 2.5 min; P = ?

Convert: 18 kJ = 18,000 J; 2.5 min = 150 s

Equation: P = E / t

Substitute: P = 18,000 / 150

Calculate: P = 120 W

If two significant figures are requested, write 1.2 × 10² W.

Plausibility check: 18,000 J spread over 150 s should give a value a little above 100 J/s, so 120 W is sensible.

Bad working: 18 / 2.5 = 7.2 W is not valid because kilojoules and minutes have been treated as joules and seconds.

Recommendation

Current from potential difference and resistance

Problem: The potential difference across a component is 12 V and its resistance is 30 Ω. Calculate the current.

Known quantities: V = 12 V; R = 30 Ω; I = ?

Equation: V = IR

Rearrange: I = V / R

Substitute: I = 12 / 30

Calculate: I = 0.4 A

If two significant figures are requested, write 0.40 A.

Reverse check: 0.40 × 30 = 12 V.

Recommendation

Kinetic energy with a squared speed

Problem: A 1,200 kg vehicle travels at 15.0 m/s. Calculate its kinetic energy.

Known quantities: m = 1,200 kg; v = 15.0 m/s

Equation: E_k = 1/2 mv²

Substitute with brackets: E_k = 0.5 × 1,200 × (15.0)²

Calculate: E_k = 135,000 J

Final answer to three significant figures: 1.35 × 10⁵ J

Relationship check: Because speed is squared, doubling the speed at the same mass would multiply the kinetic energy by four.

Recommendation

Volume from mass and density

Problem: A sample has a mass of 540 g and a density of 2.7 g/cm³. Calculate its volume.

Known quantities: m = 540 g; ρ = 2.7 g/cm³; V = ?

Equation: ρ = m / V

Rearrange: V = m / ρ

Substitute: V = 540 / 2.7

Calculate: V = 200 cm³

Unit check: g ÷ (g/cm³) = cm³, so the final unit is consistent.

Six quick checks before you move on

A plausibility check is a final test that the answer fits the equation and the physical situation. It can catch a unit or calculator error without repeating the whole calculation.

  • Unit

    Does the final unit match the quantity requested? A power answer should not finish in joules, and an energy answer should not finish in metres.

  • Magnitude

    Is the power of ten reasonable? An answer wrong by 10, 60, 100 or 1,000 often points to a conversion error.

  • Sign or direction

    Is a negative value meaningful for this quantity and the direction chosen? Mass and elapsed time are not normally negative, while velocity can be.

  • Relationship

    Does the result change as the equation predicts? At fixed potential difference, increasing resistance should reduce current.

  • Reverse substitution

    Put the answer back into the original equation. For example, 0.40 A × 30 Ω = 12 V.

  • The exact question

    Have you given the requested quantity, unit and precision, rather than stopping at an intermediate result?

Official sources and further reading

Assessment arrangements can change by nation, awarding organisation, course, tier and exam year. This guide was reviewed on 4 August 2026 using the official material below.

  • Ofqual — decision on continuing formulae and equations sheets

    Published 5 May 2026 · England policy

    Open source 1

  • Department for Education — GCSE exam support materials

    Published 26 February 2026 · England policy context

    Open source 2

  • AQA — GCSE formulae and equation sheets

    Qualification-specific sheet information

    Open source 3

  • OCR — formulae and equation sheets for 2026

    Qualification and component details

    Open source 4

  • OCR — GCSE Physics A Summer 2025 examiner report

    Illustrative evidence on rearrangement, units, working and rounding

    Open source 5

  • WJEC — GCSE Physics

    Welsh qualification information

    Open source 6

  • Qualifications Wales — GCSEs

    Welsh reform and transition information

    Open source 7

  • Qualifications Scotland — National 5 Physics

    Course guidance and Relationships Sheet

    Open source 8

  • Ofqual — regulations for GCSE science

    England mathematical-skills requirements

    Open source 9

  • AQA — GCSE Physics Working Scientifically

    Equations, units, prefixes and significant figures

    Open source 10

  • BIPM — the International System of Units

    Official SI definitions

    Open source 11

  • BIPM — SI prefixes

    Official prefix symbols and powers of ten

    Open source 12

  • National Physical Laboratory — SI prefixes explained

    Accessible unit-conversion explanation

    Open source 13

Related guidance

More guidance from this section

More guidance from this part of the Ed Centre that may help with the same decision, stage or next step.

Support and clarity

Frequently asked questions

Straight answers to the questions people ask most often.

Do I get an equation sheet in GCSE Physics?

For the remaining lifetime of the current specifications regulated in England, yes: the relevant sheet is provided for GCSE Physics and Combined Science, including relevant resits. This is not a universal UK rule. Wales and Northern Ireland have separate arrangements, while Scotland normally uses National 5 Physics. Use the current official document for your awarding organisation, course, tier and exam year.

Does an equation sheet mean I do not need to learn the equations?

For current England specifications, students are not expected to memorise the usual equations. You still need to understand the quantities, choose the correct relationship, rearrange it when required, convert units and apply it accurately. Questions must not be answerable solely by copying from the sheet.

Which GCSE Physics equation sheet should I use?

Use the official sheet for your awarding organisation, qualification title or code, tier and examination year. Separate Physics and Combined Science can use different content or layouts, and some material can be tier-specific. Avoid relying on an undated school-hosted copy.

Should I convert units before or after using the equation?

Usually convert before substitution so the values are in compatible units. Write each conversion on a separate line, especially for prefixes, minutes to seconds and squared or cubed units. Follow the output unit stated in the question.

Should I rearrange the equation before putting in the numbers?

Yes, as the normal method. Isolate the required symbol first, then substitute the values. This makes the algebra and any later arithmetic error easier to see. Correct visible steps can receive method credit where the individual mark scheme allows, but they do not guarantee partial marks.

Are formula triangles useful for GCSE Physics equations?

They can help with simple relationships containing multiplication and division only. They are not a complete method for equations involving sums, roots, powers, repeated variables or constants. Algebraic rearrangement works across a wider range of Physics equations.

How many significant figures should I use?

Follow any explicit instruction in the question. Keep the unrounded calculator value during working and round once at the final step. When no precision is stated, use sensible precision rather than assuming that one fixed rule applies to every board and question.

Do I need to show every step of a Physics calculation?

Show concise, readable lines for the equation, rearrangement, unit conversion, substitution and final answer. Clear working makes errors traceable and can preserve method credit where a particular mark scheme permits it, but showing working does not guarantee a fixed number of marks.

Sources and references

Sources and references